Post on 27-Jul-2016
description
9 Foreword
11 Product Spotlight
16 TheHydroponicStigma
19 Food Act
20 Water–muchmorethanWet
28 TheProblemwithIron
32 U.K. Food Policy
37 Five Cool Finds
38 Bananas:AbusiveFruits
44 Clover
46 SelectingaGreenhouseManufacturer
50 Who’sGrowingWhatWhere
52 AnecdotalEvidence
54 HistoryofHydroponics
62 Powder to the People
64 WhatarePhosphorus...Potassium
68 ItStartswithaSeed
72 Or…aClone
76 LightMatters–part1
IN THIS ISSUE OF GARDEN CULTURE:
Sometimes we have to look back to see what is in front of
us. We all make mistakes, and hopefully, learn from them.
When we are children we learn from our parents, peers and
teachers - we must in order to survive. “Don’t touch the fire.
Stay away from traffic. Don’t talk to strangers”... and so on. As
we grow up, we have to make decisions for ourselves. “Who
should I vote for? Is this job right for me? Should I fear (or hate)
someone, because they are different than me?” Or simple
choices like, “Should I eat processed foods, or grow a garden?”
All these decisions are based on our belief systems, and the
fundamentals of who we are.
When I was a boy the apples I ate were sprayed with DDT (colorless, odorless water-insoluble insecticide, C14H9Cl5). We were told it was safe, but of course, it turned out to be poison. The issues today are no different than they were 40 years ago. Mega corporations tell us their chemicals are safe, that our food is safe - to enjoy another Coke, and shut up. Well, they are wrong. The chemical-laden genetically modified food is not safe, and the plethora of health issues that simply did not exist 100 years ago proves it!We need to wake up, and stop trusting mega corporations and our governments with our health. There are many things we can’t change, or have very little influence over, like war and global politics. But food is not one of them. Granted, not everyone can afford to eat only organic food, and in some cases it is not even available, but we can start by changing our purchasing habits, to not buy ultra-processed foods, sugary sodas, and so on. Ignorance and apathy are our enemies. It’s time to start giving a shit about what is happening to our society, and start making our world a better place for future generations.In 100 years, I hope that our generation will be known as one that changed things for the better - because if we don’t, Monsanto may be writing the history books. 3
Eric
Garden Culture™ is a publication of 325 Media Inc.
E D I TO R SExecutive Editor:Eric CoulombeEmail:eric@gardenculturemagazine.comSenior Editor:Tammy ClaytonEmail - tammy@gardenculturemagazine.com
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D I S T R I B U T I O N PA R T N E R S• Down to Earth Kent• Maxigrow• Nutriculture DGS• HydroGarden• Highlight Horticulture
Website: www.GardenCultureMagazine.com facebook.com/GardenCulture twitter.com/GardenCulture
How It Works…Once connected to a reservoir the AQUAvalve will open,
and allow water to fill the tray to a pre-set level of 20mm.
The AQUAvalve will not refill the tray until all the water has
been used. Simple!
Watch the video: www.bit.ly/AP-valve
By consistently meeting their plants’ requirements, growers
using AutoPot achieve impressive yields, with less time
and maintenance, whilst reducing their water and nutrient
consumption. I honestly cannot say enough about this
system. It really was love at first grow.
I have been growing in Autopots for the past year, and
have been seriously impressed. Everything I have tried has
turned out amazing. Tomatoes, cucumbers, thyme, kale,
and lettuce all did so well, I decided to test out some new
plants. I cut up a piece of organic ginger, and buried them
2” deep. And 5 months later... I harvested over 3 pounds of
the best ginger I have ever seen. I now also have turmeric
and a grape vine, which are both growing quite vigorously.
There are several things that differentiate this system from
other growing methods.
1. AutoPot Watering Systems keep plants watered using
gravity pressure alone; no need for electricity, timers,
or pumps.
2. They are environmentally friendly, very little water is
ever lost. Some commercial growers have recorded
savings of up to 50% in their water and nutrient
consumption.
3. AutoPot uses patented AQUAvalve technology;
the only watering system in the world where each
individual plant controls their own irrigation, and
receives fresh nutrient-enriched water exactly when
they need it.
The Autopot Watering System is an ingenious set up for growing plants, and one that I can personally recommend to anyone. From acres of commercial greenhouses, to the little indoor garden in your basement or attic; Autopot’s simplicity and the results will impress even the most seasoned grower.
Maxibright NOW sells Sunmaster Compacts in 250W, 400W and 600W versions, providing even more choice for growers.
Find your local retailer: maxibright.com/where-to-buy/
The all new Hyper Climate Control is designed to thermostatically adjust
airflow (via variable fan speed) into your grow space on both warm days and
cold nights. As cold air can be detrimental to plant health during night cycles, the
Hyper Climate Control drops fan RPM’s down to a minimum to keep the plants
warmer, and maintain just enough airflow for effective carbon filter operation.
During warmer daytime temperatures the Hyper Climate Control will lift
and regulate fan RPM’s to maintain your digitally selected maximum ambient
temperature. Set two dials only once at the beginning of each cycle, and forget it!
· Extremely easy to use - Set and forget!
· Lowest energy use of any fan/filter/controller.
· Thermostatically changes fan speed/RPM’s.
· Constantly maintains optimal daytime temp.
· Slows fan speed to low RPM’s on cold nights.
· For use on digital EC HyperFans only.
Moonshine is a brewed plant biostimulant that is designed
to promote impressive plant growth, health and terpene
production.
Big Benefits:
• Over double previous root size
• Increased photosynthesis
• Faster maturity and increased yields
• Increased insect resistance
• Contains NO synthetic plant growth
regulators
• Contains NO silicone
To view the Moonshine video, type into
your browser:
http://tinyurl.com/MOONSVID
The Monkey Fan from Secret Jardin has two speed settings, is height adjustable, and easy to install.· 13Watts – 2200 RPM· Stays in position· Compatible with grow tent poles 16 - 19mmTo view the Monkey fan installation video, type into your browser: http://tinyurl.com/MONKEYFAN
TLEDs from Secret Jardin offer an affordable, efficient,
and versatile way of lighting your grow room. The 26W
TLEDs are available in (Blue) Growing 6500°K, or (Red)
Blooming (Red mix - including infra-red, 2100°K, and
3000°K LEDs) options. The TLED is 93% more efficient
than CFL lighting in terms of PAR per watt. Flexible
TLEDs can be hung vertically or horizontally from
grow tent poles
16-19mm using the hooks and clips
provided, or suspend your TLEDs
from the grow tent using traditional
methods, like Maxibright Easy
Hangers.
To view the easy installation of the TLED, type into your
browser: http://tinyurl.com/SJTLED
The Daylight 315 ballast system uses an advanced electronic ballast
to power the Philips Elite Daylight 315W CMH/CDM (Growing) and
Philips Elite Agro 315W CMH/CDM (Flowering) lamps for excellent
PAR per watt output.
Plants that grow under a full spectrum throughout their growth
cycle benefit from a more natural quality of light proven to prevent
stretching, and encourage higher quality growth. Culminating in
strong, healthy growth, and high quality yields.
Find your local supplier:
maxigrow.com/where-to-buy/
You can now use the DAYLIGHT 315 digital power pack with any reflector that has
an E40 lamp holder, by using the E40 to PHILIPS 315W lamp holder adapter. The E40
adapter is quick and easy to use. Simply screw the E40 adapter into the E40 lamp
holder on your reflector, then install the PHILIPS 315W CMH/CDM lamp as normal...
and you are ready to go!
Find your local retailer: maxibright.com/where-to-buy/
The Maxibright DUO uses Filp/Flop technology to
alternately illuminate two separate grow rooms
automatically when set to the 12 Hour Flip/Flop setting.
Or use the DUO 1 Hour Flip/Flop setting with two lamps
in one grow room to half the lamp heat, and significantly
reduce the grow room temperature.
Maxibright DUO one of the most versatile ballasts ever!
• Flip/Flop Technology
• Six Power Settings: 25W, 275W,
400W, 440W, 600W & 660W
• Surge ControlTM
• Soft Start Technology
• Fast Lamp Re-strike
• Dynamic Frequency Control
• End of Lamp Life Detection
• Short Circuit Protection
• Thermal Protection, Auto Reset
• LED Status with Diagnostic Feature
• Silent, Lightweight & Wall Mountable
• Runs HPS & MH Lamps
The Xpert 600W – is a low cost, vented, powder-coated metal
enclosure ballast with 600W of Genuine Power. The Xpert
power pack has a precision-wound ballast, a matched digital
SmartTM igniter, and is manufactured using quality components
from Venture Lighting. The compact size of the Xpert (L: 245mm
x H: 110mm x W: 120mm) makes it ideal for wall mounting and
grow room use.
Find your local retailer:
ma xibr ight .com/
where-to-buy/
As most of you know, hydroponics is an extremely productive and efficient gardening
method to grow almost every kind of plant imaginable. Yet, hydroponics seems to be, at
least socially, directly associated with the growth of plants that are illicit.
Why is this? After all, hydroponics,
from a scientific standpoint, is the
best way to grow anything for large
yields, and overall plant health and
vigor. Hydroponics also offers the
most efficient way to farm while
conserving water resources, as
most systems lose very little to
evaporation and mostly to plant
uptake, while the rest is recycled back
into the aquifer. Statistics from the now
defunct Progressive Gardening Trade
Association showed that customers
of most indoor gardening centers
were actually media gardeners, and few
employed water culture methods.
Some years ago, I managed an indoor gardening center that
had to tailor its very conduct around the stigma that leaned
against its very credibility. There was a company policy in place
that if anyone so much as muttered anything about any sort of
illicit plant, they had to be shown the door.
It was a don’t ask, don’t tell policy that left me giving advice on
how to grow food to a customer base that in my mind was at
least a large percentage questionable. Even though confident
many customers were in fact growing veggies, as they would
share them, I had bought into the stigma.
One day a nurse and her patient come to visit the store. The
patient is paraplegic, and his nurse is pushing him in. I’m almost
certain, stuck in my tunnel vision, that he is here to learn
how to grow something that may help alleviate some of his
discomfort. Although, I would like to help this man, I also need
to follow the law, and I’m immediately hoping he doesn’t say
something that causes me to have to ask him to leave.
He rolls up to the counter, and has trouble speaking clearly,
so we communicate through his nurse. His name is Tom Kojis.
He has Cerebral Palsy. He’s the son of a farmer with stubs for
hands. He planted his first batch of corn in 1972. He was the
editor of his local newspaper for many years. He operates a
CSA called Koji’s Produce. He’s got a lot to teach, but he’s
here wanting to learn how to expand his urban farming into his
basement with hydroponics.
Urban farming? Yes, his father who still
owns the farm, sublets enough space
to Tom to grow corn, but the rest
of the operation happens in his
modest fenced city lot - on a litany
of custom made benches, and in
4 greenhouses he has in the back
yard. An elevator will lead you
into his basement where Tom
uses a General Hydroponics’
Aeroflo to produce romaine
lettuce in the winter time, along
with a Volkswheel.
Although he’s been at it since the
70’s, Tom is always looking to improve
his gardening prowess, and since we met, has
designed and built many different hydroponic systems with
varying results. He operates 2 produce stands, and offers service
to his community in Waterford, Wisconsin - right from his front
porch, named Kojis Produce in 2005.
Tom is such a successful urban gardener that he has been able
to donate over 10,000 pounds of fresh produce to local food
banks, multiple years in a row. Tom’s ideas for the future include
expanding his reach into local restaurants that are demanding
better quality, pesticide-free produce to include in their dishes.
Tom has had to train all sorts of people just to lend him a hand
on the farm over the years, and this spawned the idea of someday
creating an urban farm/classroom environment on the site to
teach physically disadvantaged children and teens about urban
farming practices, and about Tom’s being able to overcome similar
hurdles to become the successful urban farmer he is today.
I judged Tom the day he came into the store, and unrightfully so.
Urban farming and hydroponic culture are the future of farming -
period. Its methodology is going to be a contributing component
of food security in the not so distant future. I couldn’t be more
overjoyed and thankful to have met Tom Kojis, and to have helped
him work through the innovation he represents today.
This is an awareness article, and an open apology letter.
Don’t ever judge a book, a customer, or a store by its cover. 3
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BUT...
Few involved in the chatter took time to read past the
headlines. Many assume this means that Californians can
suddenly tear out all the landscaping, and turn the entire
property into a vegetable garden. The law stops landlords
and HOAs from levying fines on residents for growing
fruits and vegetables, and otherwise punishing them
for doing so. But it isn’t license to grow your own just
anywhere. It sets specific limitations to protect residential
property values, and maintain attractive neighbourhoods.
First, it defines what types of housing it applies to for
renters and HOA members. The right to grow food
despite lease stipulations only applies to one and two-
unit buildings. Landlords cannot prohibit renters of single
family homes or duplexes from having a vegetable garden.
HOA developments have bylaws that govern common
neighbourhood interests, and AB 2561 removes barriers
to gardening for both renters and owners in appartment
complexes, planned housing developments, and
community apartments.
Secondly, this is not about urban farming. It’s a personal
agriculture provision. The produce grown under this
law can only be for personal consumption, though the
Sustainable Economies Law Center advises to check local
planning and environmental health agencies regarding
selling the harvest.
The language states that the law only removes restrictions
on private areas, and that such gardens must be in the
backyard. In appartments, food growing is confined to
containers in their personal space. A landlord can also
allow container gardens only to protect the state of the
property.
But the front yard turned veggie patch is not allowed. HOAs
can still levy fines for dead plants left standing, weeds, and
poorly maintained or unsightly backyard gardens.
This is a step in a very positive direction for many Californians,
but particularly for those living in food deserts and urban
environments. SELC sees this as legislation that will evolve.
Other states, and even other countries, should take note,
because food deserts are a huge problem across the US, and
the poor lacking access to good food is a global issue.
More Details: www bit.ly/food-act-faq 3
At the end of September 2015, California Governor Jerry Brown signed AB 2561 into a state civil code
law. Naturally, a host of blog posts, forum discussions, tweets, and hashtags erupted as word spread
across the internet. It is about time that government did something that makes it not illegal to grow fresh
food at home. And The Neighbourhood Food Act voids language in leases and homeowner association
bylaws to make this happen.
20 20
Let’s put it this way, water is much more than just
wet. In fact, with water, the further we look, the
less we know. As D.H. Lawrence said in his book
The Third Thing, “Water is H2O, hydrogen two parts,
oxygen one, but there is also a third thing that makes
it water. And nobody knows what that it is.”
Water may be the most obvious substance in our daily lives
and, at the same time, one of the greatest mysteries on
the face of the Earth. Water is everywhere and nowhere
all at once, showing up in the dew of the morning, and
reappearing as a fog rolling through the hills at dusk.
The character of water is one of grace under pressure,
constantly seeking its own level without prejudice. We
should be more like water according to
Bruce Lee, “Empty your mind, be formless, be
shapeless… like water. Water can flow, or it
can crash. Be water my friend.”
Water can be structured and energized,
and has a capacity to listen and remember.
Water has personality and is happier, more
productive, and capable of supporting life
when we provide the forms, conditions, and vibrations that
it likes. Water is the most sensitive substance on Earth, and
it has incredible capabilities when respected and treated
appropriately.
It may seem strange to give water sentient characteristics,
but it is so pervasive, fundamental, and important that there
is a limitation of language when it comes to its descriptions.
Besides, rarely, if ever, do we stop and consider what water
wants. It is collectively a passive substance in our lives.
Water expresses elegance in the grace of a babbling brook,
and power in the force of a whirlpool, or an epic surfing
wave at Jaws or Pipeline. For such a common substance, it
turns out we retain a surprisingly limited understanding of
its origins, abilities, and secrets.
Where does water come from? How many different kinds
of water are there? What is water, anyway?
The truth, on all accounts, is that collectively we don’t
really know water for what it is, or where it comes
from. We experience water more than we understand it.
Everyone knows the H2O chemical structure of water from
chemistry class, but you may be surprised to discover that
What is water, anyway?
modern popular science with all of its authority, expertise,
and experience has never actually seen a water molecule.
Major religions describe water as a seminal substance, and
at the same time destroying the Earth in great floods. Water
floated the Titanic, and sunk her at the same time. In more
ways than one, water is a vital conundrum in regards to
humanity and modern popular science.
Water has an unusually high melting and
boiling point. In some cases, hot water
may freeze faster than cold water. It’s
called the Mpemba effect.
Did you know there are at least nine
different kinds of ice, and over 80
different properties that are measurable
and able to be manipulated in water?
Water has a high viscosity, or resistance, relative to other
liquids. This also allows it to retain heat to help regulate our
weather, and be a great facilitator of sound waves.
Almost nothing behaves the way expected when it comes
to water, pressure actually reduces ice’s melting point and
thermal conductivity, and actually causes water molecules to
move further away from each other. Makes no “scientific”
sense - but so it is with water.
The strangeness of water is a result of its polarity, or the
expression of both a positively (+) and negatively (-) charged
side to its molecule, represented by the V shape chemical
structure seen in textbooks. The polarity of water makes it
capable of combining with and dissolving anything, giving it the
moniker the “universal solvent”.
One of water’s many roles is to pick stuff up and carry it
around. This includes delivering oxygen and nutrition inside
living cells, and carrying away the toxins, and also in creating
macro structures like stalagmites, or the Grand Canyon.
But it doesn’t always work in our favor. Water holds
things in a way to make them imperceptible, like an
invisibility cloak that prevents us from
seeing the substances held within. We
are mesmerized by its uniformity, and at
the same time unaware of its potential for
toxicity. Herein is the threat of runoff from
conventional agriculture and lawn care, and
public policies - like water fluoridation, and
chlorination.
Because water is a polar molecule and
opposite charges attract, water hugs itself
through a process called hydrogen bonding. We see the
influence of hydrogen bonding in clouds, the meniscus in a
glass of water, or the ability of water striders to walk on
water, creating an entire ecosystem called a neuston.
We owe our very existence to these anomalies of water.
Due to its distinctive molecular structure water exhibits
its greatest density and carrying capacity at 4°C with the
density actually decreasing below this temperature. This is
why ice floats on liquid water, which is relatively unique in
Nature, and quite significant. Imagine if water froze from
the bottom up, would life have survived ice ages on the
bottom of solid lakes?
There’s something like 1,260,000,000,000,000,000,000
liters (1.26 sextillion liters) of water found on planet
Earth. About 70% of the planet is covered in ocean,
and almost 98% of the water on the planet is in the
oceans. About 2% of Earth’s water is fresh, but 1.6% of
this freshwater is locked up in the polar ice caps and
glaciers.
Another 0.36% is found underground in aquifers and wells.
Only about 0.036% percent of the planet’s
total water supply is found in lakes and rivers,
which is still thousands of trillions of liters.
Relative to the mass of our planet, water is
the equivalent of the skin on an apple.
Water is life, but it also allows us to engage
life. To create 1 ton of steel it takes 272 tonnes
of water. It takes an average of 1741 liters of
water to make a 110 grams of hamburger. A
nuclear power plant requires 113 million liters
of water to cool its reactors… every hour.
In fact, one of the most important parts of food is water. Not
only is it required for plants to grow, but upwards of 95% of
plants and 75% of the human body are comprised of water.
Without water, we die. It is possible to survive for weeks,
even months, without food; but without water - we can last
only days.
Water is abundant, yet scarce. Almost half the world doesn’t
have access to clean water, or has to walk to get it. Most
people in the world rely on an average of 5 liters of water a
day. In the United States, on average, we use that much water
every time we flush the toilet.
The modern world is only just beginning to feel the economic
and societal pressures of peak water, and water security.
Business moguls are buying up aquifers and water rights.
Cities are privatizing their water supplies under corporations
that ban rain barrels, because they have contracts that say
they own the water before it falls. The UN even predicts the
wars of the future will be waged over water.
One of water’s
many roles is
to pick stuff
up and carry
it around
If you do the math, bottled water costs more than the price
per liter of gasoline. How can it be that something that
perpetually falls from the sky costs more than something
finite like oil that we are forced to drill from the ground?
Think about that for a minute.
Getting the most out of water in the garden is about more
than using it as a delivery agent for fertilizers, or filtering it
to remove contaminants. Water is a primary nutrient, and
using form and frequency, it can be structured to be more
efficient and valuable in the garden.
Misunderstood and flowing without form, many are
humbled, some are awed, but most in the modern
world are unaware of the wonders of water. Some have
even personified water with an agenda, as Tom Robbins
wrote in his book Even Cowgirls Get the Blues, “Human
beings were invented by water as a device for
transporting itself from one place to another.”
Water is infused into everything that we do, even our
language. We “go with the flow” when we cooperate,
or “blow off steam” when we get upset. Inexperience
is described as being “wet behind the ears,” and a bad
mortgage is described as being “underwater.” We say these
things without really even thinking about them.
My awareness of the uniqueness and the ability of water
first changed when introduced to the work of the late Dr.
Masaru Emoto in the film, What the Bleep Do We Know!?
The film documented Dr. Emoto’s work of showing how
simple intentions through sound, emotions, and thoughts
can dramatically influence the way water crystallizes.
Skeptics beware. You are free to decide that water is
merely a commodity and a receptacle, and that all water is
the same; or you can choose to view it as the great Water
Wizard as “father of implosion theory” Viktor Schauberger
did when he called water the “blood of the Earth”.
After all, the average human drinks roughly 60,000 liters of
water in a lifetime. Similarly, mature oak trees can transpire
150.000 liter of water per year!
Water is life. It is in fact what we look for on other planets
to document its presence. But a more nuanced approach
to this idea would say that water facilitates life. It is the
medium by which the energy of life, or “life force,” travels and
communicates. In the same way sound waves cannot travel in
space with no atmosphere, life waves cannot travel on Earth
without water present.
The basis of acupuncture, homeopathy, and the biodynamic
methods of farming and making compost are that subtle
energies can be utilized and imprinted into water and
“remembered,” for lack of a better word, and can actually
be manipulated and used with intention to grow healthier
people, plants, and planet.
As described by Ehrenfried Pfeiffer in the preface to The
Agriculture Course, Rudolf Steiner “called for a pail of water,
and proceeded to show us how to apportion the horn’s
contents to the water, and the correct way of stirring it…
(he) was particularly concerned with demonstrating the
energetic stirring, the forming of a funnel or crater, and the
rapid changing of direction to make a whirlpool”.
This is the basis of the biodynamic methods of stirring BD500
and BD501 for use as what are called “field sprays.” Steiner
was showing the farmers how to capture and leverage the
etheric and astral forces of plants and animals in Nature, and
using energized water as a tool of delivering them to the field.
Viktor Schauberger made many discoveries around the
regenerative nature of implosion on water. It is the implosive
moment in water where the organizational ability of water
molecules becomes vulnerable and receptive to subtle
energies. So when Steiner suggested the flow be reversed
in the bucket “to make a whirlpool”, rather than simply
“changing directions”, he was accomplishing this implosive
moment.
Intentioned growers can take advantage of this phenomenon
in their gardens by using one of the vortex-style mixing
machines on the market, or stirring fertilizer solutions
back and forth for at least 20 minutes (Steiner instructed
for an hour) in order to energize and potentize, or bring
higher order and synergy amongst the ingredients.
This is how the dynamics of a meandering river work, or
the life-giving energy experienced by surfers in the ocean
and paddlers on a river. Think about it, compared to the
efforts of dissolving oxygen with air pumps in water to grow
with hydroponics or brew compost tea, one doesn’t have
to aerate a river or the ocean, when given an opportunity,
water seeks the form of the implosive vortex in order to
regenerate and energize itself.
It is well known that water responds to celestial energies
and cycles. This sensitivity in water can be seen in the
influence of the moon on tides, or the age-old strategy of
felling trees during the new moon when the moisture and
sap are at their lowest levels. Pliny the Elder (23 – 79 AD)
advised Roman farmers to pick fruit for market before the
full moon, as it weighed more, but to pick fruit for their
own stores at the new moon, as it would last longer.
Water is so much more capable and complex than we give
it credit, so how is it that we can know so much, and at the
same time, so little about something so important?
It is not for a lack of research. Dr. Gerald Pollack of the
University of Washington describes in his book The 4th
Phase of Water the tribulations of the history of water
investigation in great detail. The Russians in the 1950s, and
the French in the 1970s, both made aggressive campaigns
to document the mysterious nature of water - but were
rebuked in the name of “science.”
The promiscuity of water makes it near impossible to
isolate pure H2O, which translates to “contamination”
in the realm of modern popular science and the scientific
method. This phenomenon of water has halted almost every
professional foray into the mysteries of water since the turn
of the twentieth century. And here we are today.
With a more direct and nuanced understanding of water, there
is enormous reservoirs of potential at our fingertips. The
capacities of water speak to the efficacy of raw food, sprouting,
and unpasteurized juicing. Water that is “structured” by living
cells is in a different, and a more invigorated state, than the
average water that we experience from the tap or bottle -
resulting in health and rejuvenation.
Not only is water structured by life more valuable, but it
turns out that we can make it easier for water to get inside
of cells as well. Peter Agre was awarded the Nobel Prize in
Chemistry in 2003 for the discovery of the aquaporins. They
are protein channels in the cell that regulate water, and they
exist in bacteria, plants, and animal cells. In the human body
alone, at least eleven different variants have been found.
The molecular structure of water determines cells’ ability to
access adequate water. Basically, what Peter Agre discovered
was that cells need to drink water one molecule at a time,
meaning, if the structure and surface tension of water is too
high we can be medically dehydrated despite the amount of
water we drink, because we are simply irrigating our kidneys,
not hydrating our cells. The same is true for plants.
In regards to the potentials of water in life and society - we
live a filtered existence. We elicit this understanding every
time we use rainwater in our gardens, invest in a water filter,
or make the decision to purchase a bottle of drinking water.
So let’s take this one more energetic step further. We must
inspire our imaginations towards water. We need more water
conservationists and connoisseurs. Pondering the importance
and mysteries of water go a long way towards levering its true
potential in our gardens and in our lives. Here’s to paying more
attention to our water, it does a body and a garden good. 3
Everybody knows the ironic tale of the thirsty old man lost at sea. This unfortunate chap, stuck in his boat,
dying of thirst, mouth as dry as dust, is surrounded in every direction by countless gallons of water but, due to
the 10,000 or so PPMs of sodium, and 19,000 PPMs of chloride inconveniently present in solution, he’s unable
to satisfy his thirst with even a single salty sip!
too often create lime-induced chlorosis. Apple, peach,
citrus, and soybean crops often suffer in this way. The
telltale sign of iron deficiency is a yellow leaf with green
veins (Hindt and Geurinot, 2012). This is because iron
is a key component of chlorophyll—nature’s very own
solar panels—so no iron means no green colour in your
leaves, and markedly reduced photosynthesis. On the
other hand, if you can give your plants enough iron, then
you’re essentially allowing them to “invest” in themselves.
Basically, you’re granting them a free license to produce
more chlorophyll, and with it, the ability to capture more
light energy.
Iron’s accessibility problems do not necessarily end
in soilless, hydroponic cultivation environments.
Furthermore, it’s all too tempting for inexperienced
growers to underestimate the importance of iron, as
well as other so-called “trace elements”. The misguided
rationale runs along the lines of—‘if plants only need, say,
between 5 and 12 parts per million of iron in solution—
can it really be that big a deal?’ Answer—yes indeed!
In experiments with tomatoes in NFT systems, large
differences in root development were observed between
plants grown in low versus high iron environments.
(Sonneveld and Voogt, 1984.) Moreover, optimal yields
Iron’s situation is quite similar. (It’s all too tempting to
claim it’s “ironic”.) For millions of years, iron deficiency
has blighted bacteria, plants, animals, and humans, and
yet, it’s the fourth most abundant element in the earth’s
crust. Take a soil sample from your backyard, and you’ll
find iron mentioned in the lab report. So why, in the midst
of all this abundance, did the World Health Organisation
recently state that iron deficiency remains the most
common nutritional disorder on the planet—and not just
in developing countries either (www.bit.ly/WHO-iron)? In
fact, over two billion people all over the world (Rodgers,
et al., 2004, Velu, et al., 2014)—nearly one in three of us—
are technically anaemic, largely due to a dearth of iron in
our diets. So what’s going on?
In order to solve our manifold iron problem, we would do
well to start with plant nutrition. Give consumable plants
enough iron, especially if they end up in the parts of the
plants we actually ingest, and it’s a happy domino effect
from there on up the food chain. However, it’s a lot easier
said than done. The key problem centres around iron’s
poor solubility in soil (Carvelho and Vasconcelos, 2013).
Iron occurs naturally as goethite and hematite—both
insoluble polymers (Ramimoghad, et al., 2014)—meaning
plants can’t benefit from them. Iron has a positive charge,
and is attracted to negatively charged clay particles in the
soil as Fe3+. (Fe2+ is attached to other molecules due to the
loss of an electron, and its unstable state.) Your plants’
root hairs continually pump out protons in the hope of
disassociating any Fe3+ oxides, languishing on the surface
of a clay particle in the soil, but it takes a whole lot of
energy (and, dare I say, luck) to snatch them up (Kim and
Guerinot, 2007., Hindt and Geurinot, 2012., Kobayashi and
Nish, 2014).
Iron plays even more hard-to-get as soil pH rises. Adding
calcium to the soil in traditional methods of liming can all
Iron EDTA Chelate
were only achievable when adequate amounts of iron
were present. Interestingly, the specific concentration
was less in rockwool culture than in NFT, perhaps due
to the increased amount of root hairs that rockwool
promotes.
Hydroponic nutrient formulations use chelated forms
of iron (most commonly EDTA and DTPA) to keep iron
in solution. A chelate is a molecule that surrounds a
metal ion and prevents it from precipitating. All sounds
like a wonderful solution to our iron problem, doesn’t
it? But, in reality, the use of chelating chemical agents
is far from ideal.
To begin to understand why; imagine a ping pong ball.
That’s your iron. Next, imagine that ping pong ball
grasped tightly by a six-fingered man. That’s your EDTA
chelate. You ask the mutant man politely for the
ping pong ball, but he’s rather attached
to it, and not letting go easily. Finally,
mainly due to your amazing skills
of negotiation (protonic energy)
you manage to persuade him to
relinquish his precious ping pong
ball. (Iron dissociation.) But—it’s
only now that you discover that
some helpful soul has deposited a
small blob of glue on the tips of each
of his six fingers. (EDTA’s six bonds with
the iron.) So, as he tries to release the ping
pong ball from one of his sticky fingers, it ends up
sticking to another. Eventually you lose patience, get
out your meat cleaver, and BASH! You relieve the man
of both his ping pong ball and his hand. (Plant absorbing
both chelate and iron.) What a palaver for just a tiny
bit of iron.
It gets worse. Chelates don’t fair
well under UV-sterilisation.
So, if you’re recirculating your
nutrient solution and treating
it with UV-C lamps, your
precious iron will fall out of
solution, and you’ll need to re-
dose before feeding it to your
plants again. To compound the
issue even more, iron is an
immobile element meaning
your plants can’t simply
translocate it from one of its
parts to another.
A solution, a revolution even, may well be on the
horizon in the form of nanotechnology. No, I’m not
about to conjure up a futuristic vision of atomic-scale
nano-bots working tirelessly to deliver iron to our
plants. Well, not exactly. Iron oxide nanoparticles
(that’s particles between 1 and 100 nanometers—a
million nanometers are equal to a single
millimetre. (Niar et al., 2010)) can be
“wrapped” in amino acids and held in
solution—allowing plants to uptake
iron via simple diffusion. No energy-
sapping, time-wasting negotiations
required.
Plant response to iron oxide
nanoparticles is dramatic, to say the
least—lush, green foliage, super fast
growth rates, shorter vegetative periods,
faster fruiting, and significant yield increases. Nano-
nutrients are set to rewrite the rulebook for both soil
and hydroponic growers—however, it is likely that only
cultivators growing very high value crops will be able to
justify their cost as the technology is barely out of the
laboratory (Khot, et al., 2012). Keep your eyes peeled
for some very interesting peer-reviewed studies in
horticultural scientific journals later this year. 3
100 years ago, and 75 years ago, the UK (and the world) faced an enemy that impacted on food supply and
food safety. We implemented rationing, and an unbreakable group strength to overcome these obstacles.
In the modern era, the UK and the world face a new set of common enemies; climate change, water stress,
energy shortages, resource limitation, social inequalities, and societal need for healthy food.
Here’s some of the questions that we’ll answer in this series,
followed by the facts, figures, and stories of the people that
these policies have affected, and continue to affect.
Q. What is the UK’s food industry worth, and
how much do we import/export?
A. The food and drink supply chain is the UK’s single largest
manufacturing sector. It accounts for 7% of GDP, employs 3.7M
people, and is worth £80Bn per year.
It exported £12Bn of food and drink in 2007. Britain is not self-
sufficient in food production; it imports 40% of the total food
consumed, and the proportion is rising.
Q. How much does the UK consume and waste
as a nation?
A. There was a rise of 4.0% in 2013 to £196 billion spent on food
and drink. We wasted 7 million tonnes of food in 2010.
Q. Food security? Who is ‘food secure’, and
how many are ‘food insecure’?
A. Food security: “The state of having reliable access to a sufficient
quantity of affordable, nutritious food”. In 2014, more than 20
million meals were provided to people unable to provide for
themselves. 1.1 million people attended food banks in 2015. This
number could be higher as the cheap ready meals that are the
staple of many in the UK would not qualify as ‘nutritious food’.
When is it time to stop calculating risk and
rewards, and just do what you know is right?
At the beginning of the year, I was chatting with Eric
(Coulombe) about our interests, and some ideas for new
articles. We were talking about food policies in different
countries, and thought an article on UK food policy would be
a good one - to see where the UK stands on social, political,
and economic food policies. So, research into the subject
began. The more I learnt about the food policies in the UK
and globally, the less I could write on the subject, or that’s
how it felt.
It was extremely disturbing to me during the research when
all the facts and figures started becoming apparent, and how
disproportionately everything is spread out - not just in the
UK, but everywhere. So, I have U-turned on writing one
article, and will split this topic into a few parts. Part I covers
the facts and figures of UK food policy in the last decade to
raise awareness of what’s happened, and is probably going
to continue to happen if we don’t take action. Next issue in
Part II, we’ll bring together the facts/figures, and try to make
sense of why the UK food policy isn’t working… There’s
more than likely going to be a ‘Part III’, but that will become
clear as more in-depth research is carried out, and more
questions need answering.
3.5 MILLION TONNES OF
EDIBLE FOOD IS WASTED A
YEAR
Q. How many people are overweight or obese,
malnourished, or living in food poverty?
A. In the UK 61.7% are overweight or obese (38,460,000), and
3 million people are malnourished. Surprisingly, people that are
overweight and obese can contribute to this 3 million people. This
shows that the quality of food available at low prices is insufficient,
or that knowledge of food, cooking, and
nutrition has severely diminished over the
last few decades.
Q. Falling food prices, in-
creased farming intensive-
ness, and a lack of sustain-
ability - where are we going
to be in 20 years?
Opinion. I am an optimist, and believe
that when these issues are raised, the
people will take action to prevent our situation from getting much
worse. These issues will be researched for Part II.
Q. Why has all this been allowed to happen,
and what can we do to reverse the trend?
A. This question will hopefully be answered in the next edition of
Garden Culture as we answer more questions, and dig deeper into
the UK food policies.
More questions will appear as we answer the questions
already asked, but that’s the nature of learning… The more
we learn, the less we know.
I want to present a couple of facts that will hopefully make
you think about the current situation in
the UK, and how that makes you feel.
Fact 1: Food prices have risen 18% in
real terms since 2007, taking us back to
the late nineties in terms of the cost of
food relative to other goods.
Fact 1.1: Median income after
housing costs fell 13% between 2002 and
2013 for the poorest 10% of households.
We have 1 in 5 people living below the poverty line.
A rise in food prices is a significant problem for the poorest
households, because they spend a greater proportion of
their income on food. Therefore, a rise in food prices has a
disproportionately large impact on money available to spend
elsewhere. This could be further education, healthier food,
a safe environment (heating, electricity, shelter), and other
amenities that improve the overall well being of the UK’s
population.
Consider a low-income household at this time
of year. Do they spend the money they have
on food, or extra heating to keep the family
warm? If they spend it on food, do you think
it’s healthy fruit and vegetables, or enough £1
frozen meals to last the week - full of sugar, fat,
and chemicals?
The BMJ (British Medical Journal) published in
2015:
“For the poorest in our society, up to 35% of disposable income
will now be needed for food, compared to less than 9% for the
wealthier. This will increase reliance on cheap, highly processed, high
fat, high sugar, high salt, and calorie dense, unhealthy foods. Re-
emerging problems of poor public health nutrition such as rickets
and malnutrition in the elderly are also causes for concern”.
(John D Middleton Vice President John R Ashton, Simon
Capewell Faculty of Public Health).
Fact 2: In 2013 the UK population was 64 million, from this
61.7% were overweight or obese (38,460,000). From 1993-
2014 the amount of overweight people went from 14.9% to
25.6%; an increase of 6.5 million people.
Fact 2.1: 500,000 individuals visited a food bank in 2015
with 1.1 million total visits.
Fact 2.2: Hospital admissions for malnutrition in England
almost doubled in the years between 2008 and 2013. (This
could be due to better screening processes.)
Fact 2.3: 7 million tonnes of food and drink (2010) is
wasted every year, with more than 3.5 million tonnes of that
being edible.
Ugly food is wasted due to its
lack of appeal in shops to the
consumer. There are mountains
of fruit and vegetables that go to
waste, because it’s not aesthetically
good enough. Policies are currently
looking at how to increase food
production, but we need to address
the distribution of food, and the
increasing food waste that would
balance the scales in favour of decreasing food poverty, and
improving societal health.
Actual food waste can be fed to pigs, but this was made illegal
due to the foot and mouth crisis. However, there is no scientific
evidence to back this up, and it needs to be researched further.
We can produce more food from our waste food, this could
be the beginning of new sustainability procedures, and further
our efforts to eradicate food poverty in the UK.
To conclude this article, and to try to emphasise the scale of
the food waste problem, ask yourselves a question;
Q. Have you ever bought a sandwich from a shop?
How many of those sandwiches had a crust?
Where do all the crusts go?
It’s not about saving the environment, it’s about creating an
environment that doesn’t need saving… 3
WE HAVE 1 IN 5 PEOPLE
LIVING BELOW THE POVERTY
LINE
A N N O T R E L L I SA no-lean, no-rot, no-rust trellis! French designer, Frédéric
Malphettes, created a configurable hanging design that
works indoors or out. He used 5mm stainless steel wire
to create over-sized octagon chain links that you add or remove
links as needed.
Blanket a wall with vines, or create individual plant ladders
hanging from the ceiling, pegs, or a frame. Made in France. Sold
through ArchiExpo.com via inquiry only:
www.bit.ly/chain-trellis.
cool finds
A I R B O N S A IBeyond cool. The thing you never
knew you must have until you’ve seen
it...floating bonsai. The brainchild of Hoshinchu in
Kyushu, Japan - the plants hover and rotate above
a pottery base. It works through repelling magnets
and balance.
Their Kickstarter page shows 6
different containers and energy
bases. They raised almost 5 times
their goal in just 6 days. Not a
bonsai expert? Watch the How
To Plant video... and grow
something seasonal. Very zen!
Check it all out:
www.bit.ly/air-bonsai..3
EDYNFinally! A way to
make growing
easier. This cool garden
gadget addresses gardening
challenges - anywhere.
It’s the first connected
outdoor garden monitor that measures soil
moisture, humidity, fertility, light, and temperature
with real time reporting, alerts, and can control
irrigation by dryness.
A Kickstarter project that not only turned into
a reality, but Home Depot USA stocked it fast.
The campaign was wildly successful within days of
launch. Looks to be out of the early adopter stage
now. Check it out: www.Edyn.com.
F LOAT I NG WALL GARD ENAs unique as Nature! The SEED planter
project is the work of internationally
exhibited designer, Taeg Nishimoto, a University of
Texas architecture professor.
Nishimoto used crumpled Tyvek to texture
concrete poured into profiles formed from river
stones. The 5/16” (8mm) thick tiles appear to float
on the wall, because the plant pot is attached to
the back of it. In his exhibit, 2” pots (4.5cm) were
used to keep them as close to the wall as possible.
More images: www.bit.ly/tn-SEED.
1
2
3
4
5
GARDENCULTUREMAGAZINE.COM 37
M U S H R O O M L I G H T SJapanese artist, Yukio Takano, makes great use of local natural waste
fashioning battery-powered LED mushroom lamps. The wiring and power
source are hidden in on the bottom.
Enchanted? Many are, yet unfortunately, Takano
lamps can only be had in Tokyo. But you can
make one! DIY’ers on Instructables.com have
easily duplicated the look substituting translucent
polymer clays for Yukio’s glass caps.
Get Inspired: www.bit.ly/takano-gallery.
How To: www.bit.ly/shroom-lamps.
GREEN PRODUCTS I GARDEN CULTURE
All the world loves bananas, indeed, it’s the 4th
most valuable crop globally. Only rice, wheat, and
milk trump bananas in trade. Yet, this fruit that
shaped the world is a problem. Not the banana
itself, but how and why an exotic fruit from the
tropics became, and remains an inexpensive, sea-
sonless staple food worldwide.
Being picked green, and gas-ripened after trans-
port sound bad? If only that was the truly unde-
sirable part.
B A N A N A S A R E C H E A P F O R A R E A S O N , A N D
R E P R E S E N T F A R - R E A C H I N G
E N V I R O N M E N T A L , S O C I A L ,
E C O N O M I C , A N D P O L I T I C A L
I S S U E S . ”
THE BANANA KINGSThe first tropical fruit to arrive in the North, bananas were
a costly luxury, but quickly became cheap food for common
folks. Normally, this happens only when an abundant crop can
be grown locally with few inputs, including labor. But bananas
are quite the opposite. A banana farm is a demanding thing in
terms of landmass, growing inputs, and labor - yet, it’s always
been one of the biggest profit-makers.
Bananas are cheap for a reason, and represent far-reaching en-
vironmental, social, economic, and political issues. The banana
trade is, and has always been, rife with
subterfuge, injustices, and economic
imperialism. An in-depth accounting of
how this became a global staple crop
has all the elements of a blockbuster
film: violence, sex, drugs, greed, politics,
corruption, war, and more.
Ever heard of United Fruit? How about Standard Fruit? Sure,
you have. The first company, now Chiquita, created the model
for today’s globalized agriculture industry, and once command-
ed 80% of the banana export trade, though the original com-
pany didn’t adapt to changing world conditions. The second
early banana trader is now Dole.
In the 1980s, 80% of the world banana trade were held by:
Chiquita, Dole, Del Monte, Fyffes, and Noboa. The first three
are long established US-based corporations, while the others
are relatively new to the game. Today these companies domi-
nate only 39% due to operational repositioning.
Until just recently, your bananas came from the side of the
world you lived on. Less travel ensured the import prices re-
mained low, but now prices plummet - regardless of harvest
origin.
A MONO MESSThere are two types of banana growers; smallholders and the
banana kings. The first use far less chemicals, require less land,
and lack clout on the market. The second, transnational cor-
porations, bring the perfect banana to market through mo-
nopoly, monoculture, and mega monocropping made possible
only through using hundreds of agrochemicals, massive defor-
estation, environmental destruction, and social and economic
control.
Additionally, the plants are all clones. It’s a rare seedless mu-
tant reproducible only by division or tissue culture, which makes
planting the crop much costlier than seed. They are all identical,
having no diversity, no immunity to pests or disease, and trans-
planted divisions increases the risk of devastating infection. It’s a
highly unsustainable crop threatened with extinction.
Until the 1950s all imported dessert bananas were Gros
Michel. Then a Fusarium species fungus called Panama Disease
wiped them all out, which cannot be eradicated from the soil
once present. All growers were forced to switch to the lesser
Cavendish banana. Now a second fungal disease, Black Siga-
toka, has reached epidemic levels globally - and a more virulent
strain of Panama Disease that spreads like the plague threatens
plantations everywhere.
Between eradicating weeds, fighting
pests and disease, and maintaining soil
fertility for the demanding feeders that
banana plants are - over 400 agrochem-
icals are used. Only cotton uses more.
Some chemicals used on bananas are
outlawed in Europe and North Amer-
ica.
Interestingly enough, the FDA reports that there are only 4
pesticides found in bananas, some suggest that the inedible
peel isn’t tested. Either way, 39-57 pounds per acre applied an-
nually is excessive! The environment, and the health of banana
workers are suffering.
HEALTH & ENVIRONMENTPests and weeds are developing chemical immunity. Increasing-
ly stronger pesticides, and in greater quantities, are being used.
On numerous plantations the chemical spend greatly exceed
their labor costs. These massive growing operations are the
result of millions of acres of deforestation, which causes soil
erosion and increased flooding. The deluge of fertilizers and
pesticides sinks into the soil, and runs off into the waterways,
eventually spilling into the ocean.
The contaminated water is killing the fish, and polluting local
water supplies, causing negative impact on the health of work-
ers and communities around plantations. An estimated 85% of
aerially applied pesticides never hit the plants, drifting over the
whole area... 22-56 times a year.
“Health impacts of extensive agrochemical use are numerous, rang-
ing from depression and respiratory problems to cancer, miscarriag-
es and birth defects. Tens of thousands of workers left sterile by the
use of a nematicide, DBCP...” --
BananaLink.org
A H I G H L Y U N S U S T A I N A B L E
C R O P T H R E A T E N E D
W I T H E X T I N C T I O N
A N E N T I R E C O U N T R Y ’ S
E C O N O M Y C A N B E D E S T R O Y E D
I N S T A N T L Y W I T H O U T T H I S
E X P O R T
SOCIAL & ECONOMICCurrently, exporters have no control
over the wholesale cost of the fruit.
Now it’s the grocers who determine
where your bananas come from by
price. This race to the bottom re-
moved country of origin preferences.
The cheapest source wins, further re-
ducing incomes for smallholders and workers.
Workers’ pay for 60-72 hours a week laboring in stifling cli-
mates over 9-12 months is based on the price their product
sells for. This week, bananas are 53 cents a pound in my neigh-
borhood, and the people who made their export possible re-
ceived 10% of that, or less. And this is for the portion of the
yield that is perfect; 30-40% of the harvest is an environmen-
tally toxic farm waste, and any less than perfect fruits arriving
for export sell locally for much less.
Even before supermarket chains had the power to deter-
mine the price of bananas, field workers and small producers
weren’t making much money. Many already existed in poverty,
unable to pay for basic living needs - and now they make less,
even though their cost of living has skyrocketed. Positive social
development in banana export countries is impossible. Cheap
bananas have taken many lives, and only reinforce conditions
that have prevailed in this industry since its birth - exploiting
people, and violating human rights.
THE SOLUTION?Avoiding bananas might come to mind, but this won’t help the
millions of people living in the fragile economies created by
monoculture bananas. Nor would the loss of their industry to
destruction by disease, which will take place, it’s only a mat-
ter of time. Chemicals are only making pathogens and pests
stronger.
An entire country’s economy can be destroyed instantly with-
out this export, the population of which is already living in
poverty. This race to the bottom pricing driven by big stores
like Walmart and Aldi’s is taking even that meager bit of se-
curity away. These transnational retailers are no better than
the banana kings. They haven’t started a war, or overthrown
a government... yet, but they’re masters at exploiting humans
for profit.
After a century of availability, banan-
as are an important part of nutritious
food diversity that is ingrained in all
cultures’ diets. It’s not like we have
no options going forward - there are
other sweet, edible banana varieties.
The fruits may not be so big, they
may not be yellow, and the flavor is different. The banana em-
pires have simply chosen the largest, prettiest, and heaviest
bearing variety for their factory farms.
Banana workers need better working conditions, and inde-
pendent trade unions to educate them what that is. Huge
monoculture plantations need to be replaced with sustainable
growing models that stop environmental devastation, and re-
build the soil. Smallholders have a far better model. Diversity
of crops, even of banana varieties themselves is needed. And
this horrible misuse of many for the benefit of a few, along with
disproportionate economic and political power that rides on
top of it all needs to be abolished.
How we get there is the cause of much debate. Introducing
more sustainable dessert bananas to replace the Cavendish
variety is long overdue. Many unknown-to-the-global-market
varieties have better flavor, but Chiquita has been working
on developing one for commercial production through hand-
breeding. Known as GCTCV 219, it’s both sweeter and better
tasting, and testing of it started in Australia and Asia in 2014.
Don’t boycott all bananas. There are organic and fairtrade
brands available, both of which do a lot in terms of alleviating
the wrongs that traditional banana growers have brought to
the land, the forests, their workers, and the local population.
Yes, they cost a bit more, but
fair trade bananas pay workers
higher wages, and give them
safer places to work under
better working conditions.
Covering a topic this vast in
so few words is impossible.
I’ve barely scratched the sur-
face. 3
DIG DEEPER:· www.bit.ly/science-quarterly
· www.bit.ly/bananas-shaped-world
· www.bit.ly/Banana-Link
· www.bit.ly/rfa-bananas
· www.bit.ly/fairtrade-bananas
· www.bit.ly/banana-chain
· www.bit.ly/ethical-consumer
· www.bit.ly/tropical-race-4
large fields. Clover can also be used as a companion for
taller plants, both for weed control while living, and as a
nutrient source as they complete their life cycle.
Since clover makes its own nitrogen, it can be planted
in areas with poor or overworked soil such as lawns to
help improve them. It can be used either as an addition to
existing grass lawns, or as a replacement for them. Once
established, clover is more drought tolerant than grass,
needs less fertilization (generally none), is aggressive
enough to push out most weeds, and even comes in dwarf
varieties to minimize the need for mowing. It is also a
favorite of honeybees, who could use all the help they can
get these days, and is even resistant to pet urine browning.
When the clover plant dies, it can be left in place to
decompose and enrich the soil, or be harvested and
composted to feed to other plants. This aspect of clover is
why it is known as one of the “green manure” plants, and
why it is a common plant to include in crop rotations. The
clover grown one season can be turned under or mowed
down to help feed whatever plant is grown next in the
rotation.
If for some reason a garden area won’t be used for a
season, consider sprinkling some clover seeds. Mix the tiny
seeds with sand to help with even coverage, and give them
enough attention to get them started well. Crop rotation
techniques can be used in small garden plots just as well as
Clover is a useful legume that is related to peas and beans. It also has pretty, if somewhat plain,
flowers when allowed to bloom.
One of the most useful aspects of clover is its ability to pull nitrogen out of the air. As with
other legumes, it can form a symbiotic relationship with host specific nitrogen fixing bacteria
called rhizobia. In the case of clover, the specific bacteria is Phyllobacterium trifolii. Commercial
clover seeds are often inoculated before sale to ensure the presence of the bacteria. A clover
plant that has rhizobia bacteria will form root nodules. The root nodules have value, because
there the bacteria can fix nitrogen directly out of the atmosphere, which it supplies to the plant.
When used as a lawn, there are a few drawbacks. First of
all, it is not as resistant to foot traffic as grass, which is a
legitimate concern for those folks that have family rugby
matches out on the front lawn, if it is to be used as a
playing field, grass is probably a better choice. For the rest
of us, just put some paving stones along whatever path
gets worn from entering and exiting the house, and enjoy
not needing to push around a lawn mower as often.
The second drawback has led to an unfair smear campaign
against the noble clover mounted by the broadleaf
herbicide people. Namely, that it can be killed with
broadleaf herbicide weed killer. These companies even
regularly advertise the effectiveness of their products
against clover, as if to suggest it is something undesirable
that should be killed. In other words; they make a product
that kills off a drought tolerant, self-fertilizing, low
maintenance lawn, in preference for water hogging, soil
depleting grass that needs mowing every week or two, and
are proud enough of that to advertise the fact.
The solution to the second drawback is simple, don’t spray
your lawn with broadleaf herbicides.
The third is a fair point, and it is that for best appearance,
clover lawns should be reseeded more often than grass
lawns. A partial solution to this is to allow the clover to
flower, set seed, and supplement with additional seedings
as needed. While this does incur both cost and labor, there
is the savings from not buying fertilizer, mowing as often, or
watering as often to consider.
Clover is one of the plants I recommend serious gardeners
to familiarize themselves with, it touches on a lot of
important concepts, including the sustainable fertilization
of crops. 3
If you are a small or a medium indoor gardener
thinking about scaling up, and building a commer-
cial greenhouse... beware, a lack of knowledge has
been revealed. From industry investors to famed
consultants, very few have built a greenhouse, let
alone an eff icient structure with specif ic technol-
ogy f ine-tuned for a specif ic crop. There is a mul-
titude of options for greenhouse manufacturers,
and most are f ighting for their place in line to
dominate new sectors in horticulture.
With the overload of choices, charismatic salesman, and
the size of this investment - you should not rely on personal
knowledge of other industries. Building a greenhouse is very
specific. The best approach is to hire a consultant that knows
greenhouses. Knowing how to operate a greenhouse does
not qualify one to design the structure or systems. For this,
you need to have built greenhouses, as well as remodeled
them in a multitude of situations.
The best analogy I have come up with for building a well-
designed greenhouse is the similarity to climbing Mt. Everest.
Even experienced climbers hire the Sherpa to lead the way,
and help bear the load - just as your greenhouse consultant
should do. It is an immense task to complete from design,
licensing, and permitting to selecting equipment, and planning
the budget with a reliable timeline.
Don’t slack on your Sherpa selection! They should have a
track record of success, and be able to provide other happy
customers as references. The consultant, when asked, should
be able to tell you of a time or two where they’ve failed, and
explain what was learned. None of us are perfect, and if you
haven’t messed something up along the way... you haven’t done
it very long. Finally, check the credentials. While a degree and
work history aren’t everything, they certainly provide a solid
foundation. The cost of a consultant may be expensive, but
like a Sherpa, they will save you money, or even your life. And
don’t be alarmed when they ask to be paid in advance (just in
case you fall off the mountain along the way).
When selecting a greenhouse manufacturer, the consultant
should be involved every step of the way. I have worked with
many different greenhouse manufacturers, and not once
have they designed a facility the way I wanted it the first time
necessary. Yes, a sealed greenhouse with
a low amount of outside air exchange may
get very hot, but with properly designed
and installed cooling systems, and energy
curtains - we can accomplish amazing
things. The opposite is a cool, dry natural
environment that will easily be duplicated in an open air flow
greenhouse simply by creating air exchange. In any open air
scenario, air filtration should be used to prevent insects, such
as thrips.
Finally, if you are well-funded, and aspire to be a true
pharmaceutical production facility, there are food safe, and
without input. There are so many factors
that go into the design. At the top of the
list is preventing problems, not fixing
them after they arise.
The next consideration is the local
environment: wind, heat, snow, hail, humidity, and light
levels. Every single location is different, and the structure
should reflect that.
The other obvious consideration is the crop itself. Some
plants prefer it to be hot and humid, this means in a high
humidity environment where a sealed greenhouse may be
SCALABILITY IS THE KEY TO LONG TERM
SUCCESS
aseptic greenhouses available. The
options for these extremely high tech
systems run into the millions of dollars.
Once you are to the point of selecting
the greenhouse manufacturer, there
is a high likelihood you have at least a
small team of people working on the
process. The greenhouse manufacturer
should be an addition to the team, not
the coach. Being a team player is often
difficult for greenhouse manufacturers, because they have
their way of doing things. They like to build what they always
have, and fear change. While someone has to develop the
greenhouse layout, it is a team decision. At the end of the day,
the greenhouse manufacturer will build it how it is requested.
Planting density is probably the most subjective piece of the
design puzzle, and every grower will have different sizes desired
for plant stages, which creates complexity of the design. The
main key of the layout for a facility like this is what I call a
‘single direction flow through’ design. Basically, that means
a first in, first out protocol, but if the processes themselves
aren’t incorporated into your design, once the greenhouse is in
production mode, employees will continually be bumping into
each other - creating traffic jams, lowered productivity, and
potential for increased contamination.
Scalability is the key to long term success. Most commercial
greenhouses that stay in business for decades have expanded,
and the most efficient designs are the easiest to scale. Literally
to the point of taking down one sidewall, and adding trusses
connected to new piers expands the greenhouse in one
direction, and with limited disruption to production.
Scalable automation creates precision in a greenhouse. It not
only removes a majority of the user error, but also creates
uniformity among the crops. The degree of the precision
created varies widely based on the equipment selected. For
example, some systems I use can have a plus or minus five
degrees variation in temperature,
where more expensive integrated
systems may have a plus or minus half
of a degree in fluctuation.
The installation and build of the actual
greenhouse is a feat, in and of itself.
Something always goes wrong. This is
where any design problems become
reality, and have to be fixed quickly,
and without slowing down the overall
build in order to minimize additional expense. Very often local
contractors will be used, but they will have supervision crews
directly from the greenhouse manufacturer. This is standard
practice, as the build itself isn’t rocket science - the hard part
is in the design.
A greenhouse manufacturer’s track record is very often their
selling strategy, but this track record can be deceiving. First
off, just because you have built more facilities than anyone
else, doesn’t mean any of them were built properly, and
building in one environment doesn’t make you able to build
in opposite ones. Asking to talk with previous customers, or
finding existing operators in other locations with the same
greenhouse is a major step toward finding the right builder.
In the end, you want a builder who will provide true ongoing
support, not just land a sale and walk away.
In closing, a greenhouse can cost anywhere between £374 and
£1872 per meter square, but how it is designed is easily the
difference between success and self-destruction. A builder will
always try to sell you a bigger structure than you ask for. Yes, it
is good for his commissions, but there is an economies of scale
factor. Most structures decrease in cost per square meter
once the half-acre, or one-acre size is achieved. No matter
what your budget is - always tell the builder it is less. This
will help anticipate the extra costs that are associated with
every project, much like buying a house. Finally, have a Sherpa
(consultant) that you trust with the life of your business,
because in the end, he or she is your guide to glory! 3
HOW A GREENHOUSE IS DESIGNED IS EASILY THE DIFFERENCE
BETWEEN SUCCESS AND SELF-
DESTRUCTION
2) Inversadale, Ross-shire
Population 1000
It’s not safe to assume that people beyond big cities have
space for growing food. Surprisingly, even people in tiny
remote villages need allotments. Such is the case in the
Scotland Highlands, where the gift of community garden
space changed the lives of the residents in this crofting
community a few kilometers beyond Poolewe. Even country
folk want a better food source, control over how it’s grown,
and environmentally friendly production.
Originally, the donated land was divided into plots for locals
to grow their own produce, but the group has evolved. Their
efforts have grown into something bigger. Thanks to a grant,
Good For Ewe acquired some poly tunnels, making year
around crops possible. They built a rainwater collection tank
for irrigation, and soon altered their production plan inside
and out to dedicate space for market growing.
60 members strong and growing like a weed.
Learn more: goodforewe.org
1) Kennington, South London
Urban GreeningThe Keeper’s Lodge at Kennington Park is buzzing
with green activity. It’s the home of Bee Urban, a social
enterprise doing all kinds of positive things with a focus
they call “honeybee-centric.” It all started 8 years ago
when London beekeeper Barnaby Shaw moved in with
four hives, and some big ideas. He’s an experienced
apiarist, having helped his father with his beekeeping
operation as a boy, and eventually taking over.
If you’re going to keep bees, you need bee food, so
they’ve transformed the outside space to provide year
around forage with fruit trees, flowers, and vegetable
gardens. The volunteer-powered organisation’s training
center, known as the Bee Barn, was built with recycled
materials. Today, Bee Urban maintains over 30 hives in 7
locations, and promotes environmental practices through
education, like urban beekeeping, solar and bio digester
energy, building bicycles from recycled parts, and more.
Process more valuable than the outcome.
Learn more: beeurban.org.uk
3) Penallt, Monmouthshire
Small Ain’t Useless
The idea that a 117 acre farm is too small to be useful or
profitable made TV presenter Kate Humble angry - so angry,
she set out to save a council farm near Monmouth from
being split and developed. Mission accomplished, it became
the site of the UK’s first closed-loop aquaponics system.
Conventional agriculture is definitely wrong, because Upper
Meend Farm is very useful, and profitable today.
Besides the passive solar greenhouse containing the
sustainable aquaponics project, there’s a lot going on
here. It’s a working farm breeding sheep and cattle, doing
permaculture, has a new orchard, a cafe, farm stays, and
courses on rural skills, smallholding, and food. Through Kate’s
company people learn they don’t need tons of land to be
more self-sustainable. The farm also boosts local economy
supporting other businesses.
A very interesting place!
Learn more: humblebynature.com
4) Wester Hailes, Edinburgh
Rethinking GreenspaceCouncil estate greenspace lawns are great for providing
a spot for recreation, but they’re rethinking its purpose
in this southwest Edinburgh neighborhood. Recently, the
Edible Estates initiative established community gardens
for residents with allotments, food hubs, and play spaces
for children. It’s a collaborative effort between the Health
Agency, the city, and urban design agency, Re:Solution, to
increase the wellbeing of the community, and decrease
maintenance costs.
The estate dwellers in Wester Hailes have really
embraced this. The plots are full, growers are socially
active, pitching in to help one another. It’s been such a
huge success that Edible Estates is exploring opportunities
to extend the program. They’re encouraging residents
to set up bird boxes and wildflower plantings, and
looking into providing training and jobs in intensive food
production.
Awesome! Inspired by London’s Poppy Estate video on
YouTube. Learn more: whee.org.uk 3
it is presented in documentary format. We are easily fooled
by presentation if we do not master the art of the science.
YouTube offers a great platform for anecdotal evidence.
There are all too many examples of it, and while some can
easily be recognized, others seem quite legit. They are well
produced, show high quality images and graphs, and the
presenter looks quite knowledgeable. It’s on video, the
pictures are convincing, you can see it with your own eyes,
right?
The amount of videos available on YouTube is overwhelming:
for any standpoint or belief - you can find “proof” in a video.
Some productions look extremely professional, adding to
the “reliability factor”. Specifically, grow trials have always
been popular: different methods of cultivation (for example,
different light sources) are compared, and of course, there
is always a clear winner. However, if you look at those trials
critically you can always see a few flaws. Let me take light as
an example, as this is my expertise.
With the rising of LED technology, you see a lot of
comparisons against traditional HID sources. Now, both
HPS and LED professional growers usually report a high
yield, but in comparisons you see that one lacks substantially,
even worse than you would normally expect to get as a result
from that particular technology. There are many reasons
why some of these results can be so different from what
you see in real life, and many originate from the fact that the
In this column Theo Tekstra discusses observations in the indoor garden culture. There is sometimes so much
urban legend, and so little science in this industry. It is time to “myth bust”, and have a fresh breeze move through
the industry.
Before there was YouTube, we had pure anecdotal
evidence, and it was the source of many urban legends.
Anecdotal evidence is defined by Webster as “based
on, or consisting of reports or observations of usually
unscientific observers.” Other sources define it as “based
on personal observation, case study reports, or random
investigations rather than systematic scientific evaluation.”
There is nothing wrong with sharing experiences you will
say, and indeed there isn’t. But to value this experience as
a universal truth can be really dangerous.
All definitions have this in common: it is usually not
based on scientific methods, or presented by scientific
observers. You need to ask yourself two things when
reading or viewing “evidence”:
1. Is the method used to obtain this result in any way
scientific?
2. Is the observer in any way a scientist?
We all know that the earth is not flat. So when someone
claims it is, because he sees no curvature, it is easy to identify
that as an incorrect claim. That is not so easy though, when
it concerns matters that we know little about. When we
seek information it is easy to be convinced by anecdotal
evidence, especially if it is presented by someone we
regard as reliable (whether that is true or not), or when
the presentation of the evidence looks professional. For
example, when supported by graphs and figures, or when
grower did not base the trial on scientific methods - or
used an incorrect application of the technology. Let me
give you a few examples:
• If the yield of one of the technologies is much lower
than you would normally expect, there is a flaw in the
application or test method somewhere. Guaranteed.
• LED, by and large, has a much more compact footprint
due to the fact that it is much more directional,
while HPS lighting mostly relies on overlapping fields
to create a uniform lighting and more horizontal
penetration of a crop. In small trials, or small square
shaped trial rooms, this of course gives the LED an
advantage, as the HPS fixture will spill lots of light on
the walls. In a large room this effect is much smaller.
Using more, smaller HPS sources will usually give
much better results in a small square room.
• At lower intensities the efficiency of the light is much
higher. There is not a linear relation between light
intensity and photosynthesis, as with high intensities
the photosynthetic rate levels off, coming close to
the saturation point of the plant. However, at high
intensity the yield per square meter will be higher,
which can be very worthwhile, and a great investment
when growing a high value crop. If you compare yield
per Watt, a low light intensity grow will always win
over a high intensity grow.
• Scientific grow trials are always done under standard
conditions. So external influences are eliminated as
much as possible. When determining the efficiency of
a light source you grow under similar intensity (PPFD),
in an as uniform as possible field of plants and uniform
lighting, and take the center of your field as the trial
sample. Trials are usually small scale, so size and room
factors need to be eliminated. I have seen trials done
in the same room where the different sources even
overlap with one another, making it impossible to get
a reliable result.
• Specifically comparing HPS and LED creates a problem
when you give both crops the same nutrient levels.
LED-grown plants, as they get much less irradiant heat,
transpire a lot less. Generally, this means that you have
to up the EC of your nutrient solution substantially.
• The climate in both rooms will differ, and this creates an
offset. Growing under LED and HPS in the same room
can actually be an advantage to the LED-grown crop, as
much stray light, and specifically - heat, is added to the
room, boosting the photosynthetic efficiency.
I am not saying that all of these trials are fraudulent, or
meant to deceive you. Not at all. There is a serious quest
in this industry to research what are the most efficient
and highest quality cultivation methods, and that is a good
thing. However, we do not see the same huge differences in
efficiency in the many real scientific trials that are executed
worldwide. LED light of the same intensity as HPS, for
example, is not 30-60% more efficient as some of these
trials want you to believe. In fact, there is much scientific
evidence that shows that there is not a big difference in yield
between the different light sources at the same intensity at
all. However, with LED light you are able to distribute the
light over a much more compact surface with much less wall
losses, which is a definite advantage in a small room, or on
a defined surface.
The moral of the story? You can not just pick and choose
your evidence. There is a reason why scientific trials are
scientific. 3
54
BY JEFF EDWARDS
55
HYDROPONICS I GARDEN CULTURE
progress came in fits and starts, with major discoveries followed by extended periods of
seeming disinterest
GARDENCULTUREMAGAZINE.COM
Jan Baptist van Helmont
Many written histories of hydroponic plant cultivation
methods mention the ancient Hanging Gardens of Babylon,
the first written record of which dates to about 290 BC.
Penned by Berossus, a Babylonian writer, priest, and
astronomer, we only know of Berossus’ writings through
quotes by later authors. Five primary authors, including
Berossus, are responsible for what we know of the Hanging
Gardens today. Their accountings were all written at a later
time, based on now lost, previously written accountings by
others.
Modern research questions whether the gardens were in
Babylon at all, yet the premise that the gardens would in
some way qualify as “hydroponic” is doubtful, based on
observations by these early writers. Diodorus Siculus,
writing between 60 and 30 BC, referenced the 4th century
BC texts, Ctesias of Cnidus, for his description of the
gardens. After detailing their construction, he includes
the following passage, “...on all this again earth had been
piled to a depth sufficient for the roots of the largest trees;
and the ground, when leveled off, was thickly planted with
trees of every kind...”
Quintus Curtius Rufus, writing in the 1st century AD,
references writings of Cleitarchus, a 4th-century BC
historian for Alexander the Great, who also described the
“...deep layer of earth placed upon it and water used for
irrigating it.” Philo of Byzantium, the author who identifies
what we accept today as the Seven Wonders of the Ancient
World, writing sometime around the 4th or 5th centuries
AD, mentions that “...much deep soil is piled on, and then
broad-leaved and especially garden trees of many varieties
are planted.”
Based on these accounts alone, it seems doubtful that the
Hanging Gardens of Babylon could in any way be considered
soilless. In all fairness, the irrigation systems required to
bring water to plantings of the reported scale, described
in the form of aqueducts and water lifts, are similar in
concept to irrigation methods employed today in modern
hydroponic systems.
Another oft mentioned comparison to modern hydroponics
in the Old World are the “floating gardens” built by the
Aztecs in the 14th century AD. Arriving in the Valley of
Mexico, the Aztec people found a landlocked swamp with
five large lakes surrounded by volcanic mountains. For some
reason, they chose to settle in swampland surrounding Lake
Texcoco, and decided to build their capital city on a small
island in the lake. Lacking any extra land for growth, the
people started building what were essentially rectangular
islands, constructed of soil, compost, and sludge from the
lake bed.
Contrary to popular belief, these islands, or “chinampas”,
didn’t float at all, but were rather attached to the lakebed
using willow tree cuttings and a variety of materials
including stones, poles, reeds, vines, and rope. Chinampas
were incredibly fertile and irrigation was unnecessary since
water wicked up from the lake. As many as 7 crops could
be harvested in a single year due to the unique methods
of composting and mulching developed by the Aztec
farmers of the time. However, based on their method
of construction it’s clear that the Aztec chinampas, like
the Hanging Gardens of Babylon, cannot be classified as
hydroponic either.
Some of the earliest recorded research into the actual
reasoning behind the growth of plants, published
posthumously in 1648, was written by a Flemish chemist
known as Jan Baptist van Helmont (1579-1644). In fact,
authorities detained van Helmont in 1634 during the
Spanish Inquisition for the “crime” of studying plants
and other sciences, and sentenced him
to two years in prison. And while van
Helmont was primarily known as the
first to articulate that there are gaseous
substances that differ from ordinary
air, as well as introducing the word
“gas” into the scientific lexicon,
he is also known for a single
Hydroponics, now commonly defined as the soilless growth of plants, has its root foundations in simple observa-
tions by early progressive thinkers and tinkerers. Like many scientific discoveries and their evolution to commercial
application, progress came in fits and starts, with major discoveries and realizations followed by extended periods
of seeming disinterest.
experiment he conducted
using a willow tree to
determine from where
plants derive their mass.
This research is commonly
known as “the 5-year tree
experiment”…
“But I have learned by this handicraft-operation that all
Vegetables do immediately, and materially proceed out of the
Element of water onely. For I took an Earthen vessel, in which
I put 200 pounds of Earth that had been dried in a Furnace,
which I moystened with Rainwater, and I implanted therein the
Trunk or Stem of a Willow Tree, weighing five pounds; and at
length, five years being finished, the Tree sprung from thence,
did weigh 169 pounds, and about three ounces: But I moystened
the Earthen Vessel with Rain-water, or distilled water (alwayes
when there was need) and it was large, and implanted into the
Earth, and least the dust that flew about should be co-mingled
with the Earth, I covered the lip or mouth of the Vessel with an
Iron-Plate covered with Tin, and easily passable with many holes.
I computed not the weight of the leaves that fell off in the four
Autumnes. At length, I again dried the Earth of the Vessell, and
there were found the same two hundred pounds, wanting about
two ounces. Therefore 164 pounds of Wood, Barks, and Roots,
arose out of water onely.”
Historians have deduced that the experiment was likely
not an original idea, rather one motivated by Nicolaus of
Cusa’s 1450 description in De Staticus Experimentis of a
similar experiment that was apparently never conducted.
Further research puts the concept of the experiment
back to a Greek work somewhere between 200 and 400
A.D. And while his research method is completely lacking
in scientific validity, it was van Helmont’s line of inquiry
and experimentation that would ultimately lead to the
understanding of photosynthesis.
In 1699, John Woodward (1665-1728),
an English naturalist, antiquarian, and
geologist challenged Helmont’s theoretical
deductions by publishing the results
of “water culture” experiments he
conducted using spearmint grown in
differing sources of water. His experiments
showed that the spearmint grew better
in water to which he added very small
amounts of soil, versus “plain” water, and
distilled water. His research also led him to
the differing conclusion
that more than water was
necessary for plant growth,
and that soil was at least
partly responsible for the
increase in the mass
and weight of plants,
indicating that he too failed to clearly grasp the
fundamental concepts of plant nutrition.
Unfortunately, progress in these areas of research
remained stagnant until the first proper water
culture experiments undertaken by a French
agricultural scientist and chemist, Jean-
Baptiste Boussingault (1801-1887), around
1840. Boussingault had established the
very first agricultural experiment station
near Alsace, France four years earlier, and
was responsible for a plethora of discoveries
related to soil chemistry and plant nutrition. Many of his
experiments involved raising plants in various soil substitutes,
1699: John Woodward conducted
experiments growing in differing sources
of water
John Woodward
including sand, ground quartz, and charcoal,
which he irrigated with solutions of mineral
nutrients.
Also in 1840, Boussingault’s fan and
contemporary, German chemist Justus
Freiherr von Liebig (1803-1873), published
Die organische Chemie in ihrer Anwendung
auf Agricultur und Physiologie (Organic Chemistry in its
Application to Agriculture and Physiology), which proffered the
then ridiculous proposition that chemistry could drastically
increase yields, and cut the costs associated with growing
food. As a boy, Liebig had lived through “the year without
a summer”, a volcanic winter event that occurred in the
northern Hemisphere after the massive 1815 eruption
of Mount Tambora in what is now known as Indonesia.
Near total crop losses that season led to widespread food
shortages, causing a global famine, and much of Liebig’s
later work towards increasing world food production was
reportedly shaped by this unsettling experience.
Liebig made significant scientific contributions to
agricultural chemistry, and was the first to put forth a
theory on mineral nutrients, identifying as essential to
plant growth the now familiar elements including nitrogen
(N), phosphorus (P), and potassium (K). Interestingly,
Liebig’s major downfall was his lack of experience in the
practical applications of his research. One of his best
known achievements was developing nitrogen-based
fertilizer, arguing in the 1840’s that it was necessary to
grow the best possible crops. However, he later convinced
himself that there was plenty of nitrogen supplied to plants
through ammonia contained in precipitation, and strongly
argued against using nitrogen in fertilizers in his later years.
Despite his wavering, he is commonly known as the “father
of the fertilizer industry” - not only for his identification of
nitrogen and other elements as being necessary for plant
growth, but also for his development of the Law of the
Minimum, which observed how individual
nutrient components affected crop
growth.
In 1860, Ferdinand Gustav
Julius von Sachs (1832-1897),
a German botanist and author
of Geschichte der Botanik
(History of Botany) (1875),
a highly regarded historical
chronicle of the various branches of botanical science
from the mid-1500’s through 1860, published his nutrient
solution formula for “water-culture”, and revived the use of
this technique as the standard tool when researching plant
nutritional needs. His plant nutrient formula, with only
minor changes, was almost universally used for
the next 8 decades.
Sachs’ experiments blazed the trail,
and in rapid succession, other
scientists followed up his work - the
most notable of which was Johann
August Ludwig Wilhelm Knop
(1817-1891), a German agricultural
chemist. While Sachs’ interest
lies primarily with studying plant
processes while establishing botanical
knowledge, Knop can rightfully be
called the true father of water culture, as his
experiments laid the foundation for what we now know
today as hydroponics.
In his early experiments, Knop sprouted seeds in sand and
fiber netting before transplanting the seedlings into cork
stoppers with drilled holes, securing them with cotton
wadding, and then suspending them in glass containers filled
with solution. By doing so, Knop inadvertently established
the technique most widely used for future laboratory
experiments.
johann august knop
Julius von sachs
Justus von Liebig
johann august knop
Using this method, Knop was the first to realize that plants
gain a large amount of weight simply from the food stored
in their seeds, and that seeds provide nourishment to the
parts of the plant that form first. By this time it had also
been established that soil nutrients must be in a soluble
form for plants, and that the amount of soluble nutrients in
soil was miniscule compared to those that were insoluble.
These two pieces of information would form the basis for
Knop’s future scientific experimentation.
What wasn’t available then were specific ways to measure
these properties, such as osmotic pressure, nor did
researchers of the day have any idea of what those
properties might be. And while Knop deduced that nutrient
solutions that were too concentrated might do more harm
than good, he had no idea why.
Despite this lack of understanding, in 1860, Knop
successfully grew plants, without soil, weighing many times
more than their seeds and containing a larger quantity of
nutrients. In 1868, other scientists using Knop’s methods,
grew buckwheat weighing 4,786 times more than its
original seed, and oats weighing 2,359 times more. These
experiments firmly established the fact that plants can
indeed be grown successfully, and productively without
soil.
Over the next few decades, little effort towards developing
commercial applications continued to leave the promise of
water culture unfulfilled. William F. Gericke, the man who
actually coined the term “hydroponics”, in his book The
Complete Guide to Soilless Gardening (1940), laments the fact
that “... after 1868, the conditions were as auspicious for
the birth of hydroponics as they were in 1929,” the year
Gericke began in earnest his research to find out if food
crop production using water culture could be commercially
viable.
In the next installment, we’ll explore events occurring in
the 20th century that led to the birth of hydroponics as it
is known today, as well the missteps and misinformation
that again led to its virtual abandonment as a practical
alternative method of food production for many years to
follow. 3
In an industry where dollars make sense, everyone is always looking for the next big thing. That amazing
new product that gets people excited about the industry all over again. Is it possible that powder nutri-
ents are it? It’s not like powdered nutrients are a new concept. In fact, they are the most simple, obvious,
and age old ingredient in an industry that has become over conceptualized by innovation. But sometimes,
when you get straight down to the root of things, less is more, and easier is better.
There are countless companies that have made an
attempt to get their foot in the door in the nutrient
game. Plant nutrition is an enormous industry that has
the power to revolutionize our food supply, and everyone
wants a piece of the proverbial pie. In hydroponics,
liquid nutrients have been the standard for decades, but
for growers who value efficiency, simplicity, and ease of
use, powders are becoming more and more appealing,
and appropriate – and here we evaluate a few of the
reasons why…
Dollars. Everybody wants more of them. And powders
help you save them. Whichever way you look at it,
powdered nutrients are more cost effective than liquids.
It is very expensive to ship heavy bottles of liquid here
and there, and powders eliminate that problem. Powders
give you a lot more bang for your buck, and can finally
give you more equal results than a full-on multi-bottle
liquid nutrient regimen, but don’t be fooled, because
not all powders are created equal.
Over time powdered nutrients have gotten somewhat
of a bad rap for being too crude, incomplete, insoluble,
etc., which is why liquid nutrients have always taken
center stage. However, there are a few innovative
companies that are changing the stigma, and coming
out with powdered nutrients that are revolutionizing
the industry. They are surpassing the potential of their
dry predecessors, delivering high quality, easy to use
formulas that threaten to make conventional feeding
schedules a thing of the past.
When looking for the best powdered nutrient brand,
look for one that delivers complete results. Many
powders will only offer macronutrients and require
numerous additives. However, there are companies
that produce a well-balanced and comprehensive
feeding program with one or few easy to use products.
There now exist sophisticated powder products
based on plant science that offer hybridized nutrients
with a high content of botanically-based ingredients
in combination with base nutrients, enzymes, and
biological components. These types of powders have
simplified the growing process without sacrificing the
complex needs of your plants.
Powders offer consistency. Specially-micronized
powders offer uniform precision in every feeding. It
allows growers scalability, which is very important for
growers that want to go big with less room for user
error. If someone is pouring liquid from six to eight
bottles, there is a lot more room for mistake versus
weighing out a set amount of grams of powder. Look for
a powder that is completely soluble in water, so it can
be used in every medium without leaving residue, or
clogging mechanical components.
Most water-based nutrients have a limited shelf life.
They lose their efficacy the longer the vital elements
are suspended in their liquid medium. Liquids are also
susceptible to heat and cold. Powders are not, and they
have virtually no expiration. They can be stored for a
very long time, and still offer the same powerful punch
years down the line. As soon as the ingredients in the
powder enter the water, they are activated and delivered
directly to the plant roots, optimizing nutrient uptake and
absorption. Liquid regiments require numerous bottles
because certain elements can bond together in a liquid,
leading to nutrient lockout and potential deficiencies.
Historically, powders have been associated with high
levels of heavy metals and categorized as chemically
“dirty” and inferior to liquids. Some of the companies
producing powder nutrients today are passionate about
growing, have a deep-rooted love for our industry,
for plants, and the people who grow them. They are
working hard to change that reputation.
We recognize the potential that this new generation
of powdered nutrients offers the hydroponics and
gardening industry. When you get right down to it, the
proof is in the powder. 3
However, Phosphorus is essential to life, phosphates
(compounds containing the phosphate ion PO43-)
are components of DNA, RNA, and ATP, along with
phospholipids, which form all cell membranes.
This importance shows in the hydroponics industry with
the abundance of Phosphorus containing products in every
shop, in every country. Here’s how to
spot deficiencies and over fertilisation
with Phosphorus…
Deficiencies will manifest themselves
through slow growing, weak and
stunted plants, these can be dark
green in colour with the older,
lower leaves showing possible purple pigmentation. As
Phosphorus ions are fairly mobile, Phosphorus deficiencies
will initially occur in the older leaves. This is due to the
necrotic tissue (dead patches), reddening of stems and
poor rooting.
Toxicity will show mainly in the form of a micronutrient
deficiency, with either Iron or Zinc being the first elements
to be affected due to the interaction of Phosphorus ‘out-
competing’ other elements.
A ‘What is…’ article usually focuses on the individual
elements, but because Phosphorus and Potassium are
always found together in the PK boosting products, we’d
like to include Potassium in this article of ‘What Is Are…’.
Potassium is a chemical element with the symbol K, from
the neo-Latin ‘Kalium’ and has the atomic number 19. You
may remember it as the soft silvery metal that reacted
vigorously with water in school. I remember it as the
silvery metal that destroyed the school’s toilet when we
P AND K ARE VERY GOOD FRIENDS IN THE HYDROPONICS
INDUSTRY
I hate it when people text me K, I’m very rarely in the mood to talk about Potassium via texting… I am,
however, very happy to have a good chat about it now, along with Phosphorous, because P and K are
very good friends in the Hydroponics industry, and it would be a shame to split them apart. We’ll start
with Phosphorus…
Phosphorus is the 15th element on the periodic table with
the symbol ‘P’. Due to its high reactivity, Phosphorus is
never found as a free element, because it is highly reactive.
Next time you check the back of a fertiliser bottle to see
what it has been combined with, you’ll usually find it’s
combined with other element containing minerals. Some
common Phosphorus combinations include Phosphorus
pentoxide and monopotassium
phosphate.
The discovery of Phosphorus is
credited to Hennig Brand, a German
alchemist who attempted to create
the fabled philosopher’s stone
through distillation of some salts
by evaporating urine. During this process, he produced
a white material that glowed in the dark and burned
brilliantly, it was named Phosphorus mirabilis (miracle bearer
of light). And for those that love to geek out like me,
the light emitted is called Cherenkov radiation. After its
discovery, it was used for stage lighting during theatrical
performances to light up the actors.
The first elemental Phosphorus produced was in 1669,
this was white phosphorus, which emits a faint white glow
when exposed to Oxygen. The faint white glow is what
actually gives Phosphorus its name, originating in Greek
Mythology Phosphorus means ‘light bearer’. In Latin it
means ‘Lucifer’ in its reference to the morning star (Venus,
and sometimes Mercury).
Although it is the 15th periodic element, it was the 13th
element to be discovered. It is perhaps for this reason that
it is called the devil’s element, or perhaps it’s because of its
use in making explosives and nerve agents for examples of
the most despicable acts known to man.
decided we wanted to see what a
bigger piece of potassium did… The
chemistry teacher was impressed,
the headmaster not so much. The
equation for that toilet water
reaction was as follows;
2K + 2H20 = 2KOH +H2
It was first isolated from Potash (the
ashes of plants), which is where it
also gets its name. Humphrey Davy
was the scientist that is credited
with finding Potassium in 1807 from
caustic potash (KOH – Potassium
hydroxide).
Potassium is involved in maintaining the water regulation of
the plant, the turgor pressure of its cells, and the opening
closing of its stomata. It is also required for the accumulation
and translocation of newly formed carbohydrates.
If your plants become Potassium deficient they become
sensitive to disease infestation, and fruit yield/quality will
be reduced. Older leaves will look as though they have
been burned along the edges, a deficiency known as scorch,
because Potassium is mobile in plants.
If you add too much potassium
the plant will become deficient in
Magnesium, and possibly Calcium due
to this imbalance, with Magnesium
deficiency likely to occur first. There
are good arguments for the use of
a Calcium/Magnesium supplement
during flowering periods of heavy PK
use. We will be looking at this in more
detail with Garden Culture’s next
edition of ‘What Is Are... Calcium and
Magnesium’.
There are two topics that you might
think we’ve missed in this article of ‘What Is…’ - the
relationship of P and K in flowering additives, and the
impending Phosphorus crisis. Both topics require an
article by themselves, so that gives you something to look
forward to or fall asleep to…
Thank you for taking the time to learn a little more about
Phosphorus and Potassium. But before I go, here’s one to
finish:
Did you hear about the time Oxygen and Potassium went
on a date? It went OK… No more, I promise. 3
IF YOUR PLANTS BECOME
POTASSIUM DEFICIENT THEY
BECOME SENSITIVE TO DISEASE
INFESTATION, AND FRUIT YIELD/QUALITY WILL BE
REDUCED
In many parts of the country, the killing cold of
early winter brings an end to the life of many annual
plants. When temperatures drop below freezing,
expanding ice crystals burst tender cell walls. For
some it is a swift death with the first few frosts, for
others the end of post-flowering decline, and still
others struggle on until finally succumbing to the
icy grip of cold. In order for the species to survive,
there has to be some way for the plant’s DNA to
be preserved past the life of the parent plant - for
weeks, perhaps months, until conditions improve.
Plants are notoriously “rooted in place,” inhibiting
their personal mobility. The ability to package tiny
plants into small containers allows for the use of
wind, water, animals, or people as carriers to expand
their territory beyond the physical reach of the parent
plant.
Seeds solve both these problems by being a tiny plant
(embryo) packaged with enough food to get started
with (endosperm), and secured inside a protective
covering (seed coat).
In plants that produce seeds; male flowers produce
pollen on their anthers that when applied to stigmas
of female flowers can fertilize the ovule. The pollinated
ovule forms a zygote, which grows into a tiny plant
Flowering plants (Angiosperms) use seeds (usually) as a means of reproduc-tion. Seeds are an amazing answer to some pretty formidable problems.
(embryo). The embryo will already have seed leaves
(cotyledons), stem (hypocotyl), and a root (radicle),
and be encased in a shell (seed coat). The shell helps
to protect the small plant, and allow it to go into stasis
until it finds itself in conditions conducive to sprouting.
Food stores (endosperm) may be inside the seed coat,
or outside it as is common in fruits.
To help the tiny plants inside seeds stay in a state of
suspended animation, excess moisture is allowed to
evaporate as the seeds dry out.
Depending on the type of plant
and conditions, the seeds may last
through winter, or other harsh
weather, to sprout in the spring -
or they may last for several years.
Seeds kept too wet may sprout
prematurely and then die, so seeds
should be kept in a dry container at
cool temperatures for best storage.
Germination often starts with
the reintroduction of moisture to the seed, and ends
when the plant ends its reliance on the food stores,
and can draw nutrition from the environment. The
requirements for germination are moisture, oxygen,
an appropriate temperature, and for some plants,
light. The seeds of most plants have a low moisture
content, which helps them have a long “shelf life.”
Before a seed will sprout, it must first be rehydrated.
When the seed comes into contact with moisture, it
draws in the water through a small (relatively small,
they can be easily seen on coconuts for example) holes
(micropyles). This moisture will cause the plant to
swell, and soften the seed coat, allowing the radicle to
break through using hydraulic pressure to seek more
moisture, and the seed leaves to swell and open to
seek out light.
One way to help with getting moisture through the
micropyle, is to soak the seeds in water for 24 hours.
Another is known as “scarification” helps to weaken the
seed coat, and allow the plant easier access to moisture.
This involves nicking the seed coat
with a sharp object, or rubbing the
seed on a rough surface, such as
sandpaper or an emery board.
Moistening a paper towel, wringing
it out, and putting it with seeds in
a plastic bag in a warm location
to sprout is another way to aid
moisture in saturating the seed.
If using this method, change the
paper towel every few days to
keep it fresh, as it is an environment conducive to
germinating plant seeds, but mold spores as well.
Once a seed becomes waterlogged, fungus can set in
and ruin it.
The amount of oxygen needed by a particular type of
plant varies. Some plants will not germinate even in the
presence of moisture, unless air is also present. For
this reason, most seeds should not be soaked directly
in water for days on end, but transferred to a better-
aerated environment after an initial day or so.
mo s t s e e d s shou ld n ot b e s o ake d i n wat e r for d ays on en d
Moist seeds will germinate at a
temperature of 68°-86°F (20-30°C),
with 75°F (24°C) being ideal for many
plants. In cold settings, a heating pad
may be used to raise the temperature
of seed trays.
Some seeds germinate better in light,
and others in dark conditions. Check
the information about the type of seed
to learn which it prefers.
Many seeds can be sprouted by simply
burying them 3 to 4 times their width, and kept moist,
but not soggy, until sprouting. To prevent the media
from drying out too quickly, sometimes domes or
plastic sheets are used to keep the humidity high while
seeds sprout. However, do not allow the seedlings to
stay too wet for too long, or fungus may start to grow
on the plant near the media, causing the fatal condition
known as “damping off.” Media should be “moist” - not
“wet.” Do not allow the media to dry out too much,
however, as once the plant has germinated, it loses its
ability to survive without water, and with such a small
root system, it can quickly dry out and die.
Quality harvests depend on quality seeds, whether
purchased, gifted, or gathered. Seeds from many plants
can be collected, and used the following year. If the
seeds are going to be collected, for predictable results
“open pollinated” varieties should be used. These seeds
will tend to produce similar plants from one year to the
next.
In late winter to early spring, it is
common to start seeds indoors
to be prepared for spring planting.
To determine when to start your
outdoor garden seeds indoors, find
out the date of the last frost in your
area. Then read the seed packet,
which should tell you how many
weeks before the last frost date to
start them.
Some plants have an additional concern
when calculating their planting dates, photoperiodism,
which means that they use the duration of their dark
periods to determine when to flower. Spring and
fall both have longer nights than the short nights of
summer. These plants bulk up during the summer, until
the longer nights of fall trigger flower, or fruit set. The
reason that this can be a concern, is that if these plants
are set outside in the spring months when the nights are
long, they can immediately begin flowering.
Depending on your area and need, it is common to start
seeds indoors 6-8 weeks before the last frost date.
Plants started indoors should be “hardened” by moving
to a sheltered location, or gradually increasing the
time the plant spends outdoors. This allows the plant
to become used to the new conditions over time, and
minimizes the shock from the change.
Starting plants from seeds can be rewarding, and cheaper
than purchasing established plants. As an additional
bonus, starting seeds indoors can extend the gardening
activity months. 3
It i s c o mm on
t o s t a r t s e e d s
i n d o or s 6 -8 we ek s b efor e th e l a s t fr o s t
d at e
Rooting cuttings is a time
honored tradition that allows
for certain plants to be propagated
asexually. It effectively allows the same plant
to be grown in multiple pots. Since the new plant
shares the same DNA as the parent plant (barring mutation)
it is commonly referred to by the term “clone”. Cavendish bananas are all
clones of the same plant, most wine and table grapes are clones, so are practically
all potatoes, and the grafts for commercial fruits and citrus.
group of cells that formed the branch that the cutting has
been taken from were mutated, then the branch may be of
a different genotype than the rest of the plant, and cuttings
taken from that branch will also be different from the
rest of the plant (but the same as other cuttings from the
affected branch).
Cuttings are able to form roots from stems and growth
nodes by using a type of plant cell known as a meristem
cell. These are undifferentiated cells that can mature into
a variety of adult cells depending on the environment that
they are exposed to. The growth tips in plants have so many
meristem cells in them that they are known as shoot apical
meristems. The meristem cells in the growth tips mature
into shoot and flower cells, adding to branch length, leaf
development, flowers, and fruits depending on which type
of cell is called for.
Another high concentration of meristem cells can be
found in the root tips, which are also known as root
apical meristems, which mostly mature into root cells.
It is important to note that the meristem cells found in
the growth tips, along the stem, and in the roots, are all
exactly the same, and it is the conditions around them that
determine what they eventually develop into.
Cuttings are generally taken during the most vigorous part
of the plant’s growth cycle, but before flowering starts.
Since the parent and the cuttings share the same DNA,
they will be the same genotype, if grown under similar
conditions, that will tend to express as similar phenotypes
(the directly observable attributes of the plant). So a cutting
from a yellow flowered plant will also have yellow flowers,
and a cutting from a female plant will also be female. This
can be used to good effect when a lot of the same color
flower is desired in varieties that have a variety of colored
flowers.
This method of propagation can also be used when
determining gender, as a cutting can be taken, and
exposed to a flowering light schedule while the parent
is left under growth lighting (or vice versa). Whatever
gender the parent shows will also identify the gender of
the others. Clones can be useful to propagate a number
of plants with the same characteristics, such as when a
roomful of relatively identical yellow flowered female
plants is desired.
Cuttings from plants grown from cuttings have the same
DNA as the original plant. Usually, anyway, if the original
I n d ole but y r i c a c id or
n aphth a len e a c e t i c a c id en c ou r a g e
r o o t d evelopm ent
prevent the cutting from suffering
from terminal wilt (which will kill
it), keep the cut end in water
until it is ready to be used.
Before putting in the rooting
medium the ends of the cuttings
can be exposed to a plant auxin hormone, such as
indolebutyric acid (IBA) or naphthaleneacetic acid (NAA),
to encourage root development. Both are frequently
applied in the form of a rooting powder, gel, or liquid.
The stem end of the cutting is placed into a mild potting
soil, oxygenated water, or other suitable medium in a warm
location under moderately bright lighting. If a solid medium
is used, it should be kept moist, but not soggy. If over
watered, the end of the stem may develop a fungal infection
and rot. Under favorable conditions, roots will generally
appear within a week or two, although some plants like
tomatoes can root within a few days, and some plants may
take a month or more. As long as the shoot portion of the
plant is kept healthy, and there is no indication of root rot,
the chance still exists for a particular cutting to form roots
eventually.
Rooting cuttings is mostly a matter of getting conditions
right, and perseverance. Some plants root easier than
others, but being able to propagate asexually via cuttings is
a handy tool to add to a gardener’s skillset. 3
Grafting is basically taking a
cutting and placing it into a
matching cut in a rootstock
plant. The meristem cells in this
case grow to heal the cut. This
may be done to match superior
rootstocks with superior fruiting varieties, or as in the case
of citrus, seed grown trees may take 10 years to mature
enough to grow fruit, but a cutting from an existing older
tree grafted onto fresh rootstock can produce fruit in a
couple years. This is because the cutting and resulting
growth from the graft is already old enough to produce
fruit.
Meristem cells are also critical when using tissue culture
techniques, as their ability to mature into any type of adult
cell can be manipulated into making a complete plant from
a tiny cutting.
For a normal cutting to be grown into a complete plant,
it should include a shoot apical meristem (growth tip,
or at least a budding site) and a section of stem. It is the
meristem cells in the stem and any lower budding sites that
are induced to develop into root cells, and create new root
tips.
When taking cuttings from a plant, the cut should be neat
and clean, as it will make a wound in the parent plant. To
In the series “Light Matters”, Theo Tekstra discusses different aspects to lighting,
such as quantity, quality, efficacy, special applications, new developments, and
the science behind it. In this first episode we focus on quantity. How much
light do you give your plants? And how does that matter?
reaching a surface of a square meter every second.
This is called Photosynthetic Photon Flux Density, or
PPFD.
Unfortunately, photons are so numerous that that
would easily lead to a 20 digit number, which is a bit
hard to read and value. There is, however, a standard
unit of measurements which defines a large number
of particles such as atoms, molecules, electrons, and
photons. It is the mole. By all means, if you want to
learn more about moles, take a look at Wikipedia,
but for now, it is enough to know that 1 mole of light
is 6.22 x 1023 (the Avogadro number) photons.
The notation for mole is mol, just like ‘s’ is for second,
and ‘m’ is for meter. As we already saw light intensity
is Photosynthetic Photon Flux Density, which is moles
of light per square meter per second. The scientific
notation of “per square meter per second” is “m-2
s-1” - so for space’s sake, and to make it look real
scientific, we are going to use mol m-2 s-1 from now.
Full Sunlight at midday is about 0.0025 mol m-2 s-1, or
2.5 millimol m-2 s-1, or 2,500 micromol (µmol) m-2 s-1.
I think you will agree with me that the µmol m-2 s-1 is
the easiest to use here. Which is fortunate, because
this is the way we measure the photosynthetic
photon flux density.
To recap:
• Photons are so numerous that we count them in
moles of photons.
• Photosynthetic Active Radiation (PAR) is defined
in the range between 400 nm light (blue) and 700
nm (red).
• Light intensity is defined as the number of PAR
photons per square meter per seconds, so mol
m-2 s-1. In practice, we use µmol m-2 s-1.
Plants are Photon CountersPlants use photon strikes for the synthesis of chemical
energy, such as sugars. I say strikes, and not light energy,
because it is the number of photons that is primarily
responsible for the process, and not the individual varying
energy of those photons. Blue photons for example,
contain a much higher amount of energy. That extra
energy, however, is mostly dissipated into heat. To bind
a CO2 molecule, you need about 8-12 photons. So, you
see it is a numbers game! We need to know how many
photons hit our plants to get an idea of the total potential
photosynthesis.
Plants are photon counters. Look at photons as rain
drops: the lighter the rain, the less water reaches the
surface. It’s the same for light: the fewer the photons, the
less light plants get for photosynthesis.
Counting LightTo quantify grow light, we first need to establish which
photons to count, and how to express that in numbers.
It has been established that photons with a wavelength
ranging from 400 nm (blue) to 700 nm (red) contribute
most to the photosynthetic process. That is why we call
photons in this range Photosynthetic Active Radiation, or
PAR for short.
In order to quantify a stream of particles, we need to
count how many reach the surface, at a given time, on
a standard size surface. The international standards for
time and surface are second and square meter. Taking
this back to raindrops again: the rate of the raindrops is
defined by the number of raindrops that fall on a square
meter of surface in one second. It gives you the density
of the rain.
The same applies to light: the intensity of the
(photosynthetic) light is defined by the PAR photons
Amount of Light Per DayA light rainfall that continues for 20 hours can result in
much more water than a short heavy shower. There is a
relationship in the intensity of the rain, the length of the
shower, and the amount of water that reaches the ground.
The same goes for light: the total amount of photons
reaching your crop is based on the intensity of the light,
and the light period. The intensity, or PPFD, is defined as
mol m-2 s-1, so by multiplying this by the number of seconds
to get this intensity per day, you get the number of photons
per day, expressed in mol m-2 d-1 (moles per day). This is the
DLI - ‘daily light integral’.
Let’s work on an example.
- PPDF is 1000 µmol m-2 s-1
- Light period daily is 12 hours in a 24 hour cycle
To convert PPFD to DLI, multiply by the number of seconds
you are lighting your crop:
1000 (µmol m-2 s-1) x 12 (hours) x 3600 (seconds per hour)
= 43,200,000 µmol m-2 d-1, or 43.2 mol m-2 d-1.
And there you have it. The relationship between the light
intensity, and the amount of light per day.
Questions and AnswersArmed with this information, let’s try to answer the
following questions:
Q: If I give half the intensity of light, and double the time the
plants get it, does that have the same effect on photosynthesis?
A: Yes, it does. This is how we light tomatoes and roses in
greenhouses. They are long day plants (which flower and
fruit when there are long days of light), and they get up to
20 hours of light per day on dark days. However, if you are
flowering short day plants (which flower when the nights are
long), there is a limited period of about 12 hours in which
you can give that to your plants. So, in that case, you will
use a higher PPFD to get the same DLI in a shorter period.
Q: So basically for a higher yield, I should just give more light?
A: Yes, but there is an optimal and maximum amount of light
per day, and also a maximum intensity you can give your
plant. A shade plant, for example, can only take a limited
intensity, and short day plants do have a maximum intensity
and DLI. It is also a function of what we call the limiting
factors for photosynthesis:
- Light
- Carbon Dioxide
- Temperature
Here is a graph representing the three limiting factors:
These three have to be in a balance. When there are one or
two too low, it will cause the plant to perform sub-optimally,
and there are absolute maximum and optimal levels as well.
So more light might require a higher temperature, and/
or more CO2. It is the grower’s mission to find the right
balance for his crop, and this is just one of the balances.
Other factors are the climate (as in humidity, for example),
available water, and nutrients.
Q: What is the optimal PPFD to give my crop in an indoor
environment?
A: For that you need to know the photosynthetic response
curve of your plant, and you need to make a choice -
whether you want to harvest as much crop per invested
energy (grams per Watt), or crop per square meter (grams
per square meter). It requires an experienced grower to
do the last, as you will be growing up to your plant’s limits.
Let me explain this with a diagram, showing photosynthesis
(Pn) against irradiation (I) of a specific crop (for other
crops this may
be different). A
second variable
in this graph is
temperature:
At low intensity, you see a more linear increase of
photosynthesis when the light intensity increases.
However, with increased light levels, at some point the
photosynthesis tapers off, and at a certain level may even
cause photoinhibition. So doubling the amount of light does
not automatically mean that you will have double the amount
of yield. For every temperature, there is a saturation point:
a point where adding more light will no longer add to extra
photosynthesis. The saturation point is lower at a high
temperature, but the efficiency of the applied light is much
higher at an optimal temperature. Hence, you need to grow
at the right temperature to get optimum effect from your
light, 30°C in this example.
Remember the limiting factors of photosynthesis? The
moment you see the curve tapering off, you have reached
a limiting factor. In this case, temperature and PPFD were
variable, while CO2 is a constant. Adding CO2 will give you
a longer linear curve, so a much higher photosynthetic rate.
Q: Should I use the same PPFD during the vegetative stage of my
short day crop?
A: Using the same PPFD in the vegetative and flowering phase
will result in your crop getting 50% more light (higher DLI)
in the vegetative phase when you light it 18 hours in veg, and
12 hours in flowering. Reducing your PPFD in veg by 33% will
result in the same DLI. So, if you flower with 1000 µmol m-2
s-1 for 12 hours, giving your crop 667 µmol m-2 s-1 for 18 hours
will result in the same amount of light per day.
MORE LIGHT MIGHT REQUIRE A HIGHER
TEMPERATURE, AND/OR MORE CO2
Q: How about supplemental lighting in greenhouses? How much
do I need?
A: That depends on the DLI of the sunlight throughout the
season you grow, and your crop. The DLI you get from
natural sunlight depends on your geographical position.
Purdue University published a good overview of DLI during
different seasons in the USA:
Source: http://bit.ly/purdue-DLI
However, that is not the DLI your crop will receive in the
greenhouse:
• During a clear sky summer day of full sun you will
probably shade your plants, because the PPFD is too
high, reducing the DLI of the sunlight.
• Your greenhouse construction takes away light.
Transmission losses can be as high as 25%, or more.
Secondly, you need to know the optimal DLI for your crop,
and whether you are going to give this in a long day, or a
short day. For a short day crop, the time that you can light
your crop is limited. The light level will need to be higher
than for a long day crop, which you can light for a long time
to compensate low sunlight DLI. 3