Companion Planting:

Basic Concept and Resources

Research & compiled by Camille LeblancResearch & compiled by Camille Leblanc

While companion planting has a long history, the mechanisms of beneficial plant interaction have not

always been well overstood. Traditional recommendations used by gardeners have evolved from

an interesting combination of historical observation, horticultural science, and a few unconventional sources.

Companion planting can be described as the establishment of two or more plant species in close proximity so that some cultural benefit (pest control, higher yield, etc.) is derived. The concept embraces a number of strategies that increase the biodiversity of agro ecosystems.

Traditional Companion Planting

Table 1. COMPANION PLANTING CHART FOR HOME & MARKET GARDENING (compiled from traditional literature on companion planting)

CROP COMPANIONS INCOMPATIBLE

Asparagus Tomato, Parsley, Basil

Beans Most Vegetables & Herbs

Beans, Bush Irish Potato, Cucumber, Corn, Strawberry, Celery, Summer Savoury

Onion

Beans, Pole Corn, Summer Savoury, Radish

Onion, Beets, Kohlrabi, Sunflower

Cabbage Family

Aromatic Herbs, Celery, Beets, Onion Family, Chamomile, Spinach, Chard

Dill, Strawberries, Pole Beans, Tomato

Carrots English Pea, Lettuce, Rosemary, Onion Family, Sage, Tomato

Dill

Celery Onion & Cabbage Families, Tomato, Bush Beans, Nasturtium

Corn Irish Potato, Beans, English Pea, Pumpkin, Cucumber, Squash

Tomato

Cucumber Beans, Corn, English Pea, Sunflowers, Radish

Irish Potato, Aromatic Herbs

Eggplant Beans, Marigold

Lettuce Carrot, Radish, Strawberry, Cucumber

 

Onion Family Beets, Carrot, Lettuce, Cabbage Family, Summer Savory

Beans, English Peas

Parsley Tomato, Asparagus

Pea, English Carrots, Radish, Turnip, Cucumber, Corn, Beans

Onion Family, Gladiolus, Irish Potato

Potato, Irish Beans, Corn, Cabbage Family, Marigolds, Horseradish

Pumpkin, Squash, Tomato, Cucumber, Sunflower

Pumpkins Corn, Marigold Irish Potato

Radish English Pea, Nasturtium, Lettuce, Cucumber

Hyssop

Spinach Strawberry, Faba Bean

Squash Nasturtium, Corn, Marigold Irish Potato

Tomato Onion Family, Nasturtium, Marigold, Asparagus, Carrot, Parsley, Cucumber

Irish Potato, Fennel, Cabbage Family

Turnip English Pea Irish Potato

Trap Cropping

Sometimes, a neighbouring crop may be selected because it is more attractive to pests

and serves to distract them from the main crop. An excellent example of this is the use of collards to draw the diamond back moth

away from cabbage.

Symbiotic Nitrogen FixationLegumes such as peas, beans, and clover have the ability to fix atmospheric nitrogen for their

own use and for the benefit of neighbouring plants via symbiotic relationship with

Rhizobium bacteria. Forage legumes, for example, are commonly seeded with grasses to

reduce the need for nitrogen fertilizer. Likewise, beans are sometimes interplanted with corn.

Biochemical Pest SuppressionSome plants exude chemicals from roots or aerial parts that suppress or repel pests and protect neighbouring plants. The African marigold, for example, releases thiopene—a nematode repellent—making it a good

companion for a number of garden crops. The manufacture and release of certain biochemical's is also a

factor in plant antagonism. Allelochemicals such as juglone—found in black walnut—suppress the growth of

a wide range of other plants, which often creates a problem in home horticulture. A positive use of plant

allelopathy is the use of mow-killed grain rye as a mulch. The allelochemicals that leach from rye residue prevent

weed germination but do not harm transplanted tomatoes, broccoli, or many other vegetables.

bi·o·chem·i·cal relating to biochemistry: relating to the chemical substances present in living organisms and the reactions and methods used to identify or characterize

an·tag·o·nism 1. hostility: hostility or hatred causing opposition and ill will 3. physiology neutralizing interaction: the interaction between two or more chemical substances

that diminishes the effect each of them has individually

al·le·lo·chem·i·cal toxic plant chemical: a chemical produced by one plant that is toxic to another. Also called allelotoxin

al·le·lop·a·thy suppression of neighboring plants: the release into the environment by one plant of a substance

that inhibits the germination or growth of other potential competitor plants of the same or another species

Physical Spatial Interactions

For example, tall-growing, sun-loving plants may share space with lower-growing, shade-tolerant

species, resulting in higher total yields from the land. Spatial interaction can also yield pest control

benefits. The diverse canopy resulting when corn is companion-planted with squash or pumpkins is

believed to disorient the adult squash vine borer and protect the vining crop from this damaging pest. In

turn, the presence of the prickly vines is said to discourage rodents from ravaging the sweet corn.

Nurse Cropping

Tall or dense-canopied plants may protect more vulnerable species through shading or by

providing a windbreak. Nurse crops such as oats have long been used to help establish alfalfa and

other forages by supplanting the more competitive weeds that would otherwise grow in their place. In many instances, nurse cropping is

simply another form of physical-spatial

interaction. al·fal·fa forage crop: a European and Asian plant in the pea family, widely grown as a hay and

forage crop.

oat grass with edible seed: a grass that has edible seeds and is grown in numerous northern countries as a cereal crop

spa·tial relating to space: relating to, occupying, or happening in space

Beneficial Habitats

Beneficial habitats—sometimes called refugia—are another type of companion plant interaction that has drawn considerable attention in recent years. The benefit is derived when companion plants provide a

desirable environment for beneficial insects and other arthropods especially those predatory and parasitic species which help to keep pest

populations in check. Predators include ladybird beetles, lacewings hover flies, mantids, robber flies, and non-insects such as spiders and

predatory mites. Parasites include a wide range of fly and wasp species including tachinid flies, and Trichogramma and ichneumonid wasps.

Agro ecologists believe that by developing systems to include habitats that draw and sustain beneficial insects, the twin objectives of reducing

both pest damage and pesticide use can be attained. For detailed information on establishing beneficial habitats, request the ATTRA

publication Farmscaping to Enhance Biological Control.ar·thro·pod

invertebrate animal: an invertebrate animal that has jointed limbs, a segmented body, and an exoskeleton made of chitin. Insects, arachnids, centipedes, and crustaceans are arthropods.

Security Through DiversityA more general mixing of various crops and varieties provides a degree of security to the grower. If pests or adverse conditions reduce

or destroy a single crop or cultivar, others remain to produce some level of yield.

Furthermore, the simple mixing of cultivars, as demonstrated with broccoli in University

of California research, can reduce aphid infestation in a crop.

COMPANION VEGETABLE GARDENING

It's said that vegetables are like people, they thrive on companionship. It is believed that vegetables will yield up to twice as much when they are surrounded

with companion plants. So in this article we will discuss the top 12 vegetables and their best friends.

If you're getting ready to plant your vegetable garden you may want to try placing the various vegetable crops so you can take advantage of their natural

friends. If you have already planted your vegetable garden you may want to make some changes in

subsequent plantings later this summer.

The following are a list of the top 12 vegetables and their ideal

planting companions.

Beans--they like celery and cucumbers but dislike onions and fennel. Beets--Bush beans, lettuce, onions, kohlrabi, and most members of the cabbage family are companion plants. Keep the pole beans and mustard away from them. Cabbage--Celery, dill, onions and potatoes are good companion plants They dislike strawberries, tomatoes, and pole beans. Carrots--Leaf lettuce, radish, onions and tomatoes are their friends, Plant dill at the opposite end of the garden. Corn--Pumpkins, peas, beans, cucumbers and potatoes are nice companion plants, Keep the tomatoes away from them. Cucumbers--They like corn, peas, radishes, beans and sunflowers. Cucumbers dislike aromatic herbs and potatoes so keep them away.

Lettuce--It grows especially well with onions. Strawberries carrots, radishes and cucumbers also are friends and good companion plants. Onions--Plant them near lettuce, beets, strawberries and tomatoes but keep them away from peas and beans. Peas--Carrots, cucumbers, corn, turnips and radishes plus beans, potatoes and aromatic herbs are their friends. Keep the peas away from onions, garlic, leek, and shallots

Radishes--This is one vegetable that has a lot of friends, they are excellent companion plants with

beets, carrots, spinach and parsnips. Radishes grow well with cucumbers and beans. It's said that summer

planting near leaf lettuce makes the radishes more tender. Avoid planting radishes near cabbage,

cauliflower, Brussels sprouts, broccoli, kohlrabi or turnips.

Squash--Icicle radishes, cucumbers and corn are among their friends.

Tomatoes--Carrots, onions and parsley are good companion plants. Keep the cabbage and cauliflower

away from them.

Sometimes plant friendships are one-sided. Carrots are said to help beans, but beans don’t reciprocate. Though beans will

help nearby cucumbers. Other plants have bad companions and you'll be doing them a

favour to keep them apart. Beans and onions are natural enemies so keep them at opposite sides of the garden.

If you have a patio you might try mint to repel ants, and basil to keep the flies and mosquitoes away. Both herbs have pretty flowers and are fragrant too. Besides, they're nice to harvest and use in the kitchen. "Carrots Love Tomatoes" getting to know good and bad companions can double the bounty of

your garden. The only required work is to plan your garden planting properly.

Herb Companion Chart

The idea that herbs make good companion plants is not new. Some of the earliest written documents on

gardening discuss these relationships. When selecting your companion plants you will need to consider more than which pests are deterred. Think about what each plant adds or takes away from the soil and what effect the proximity of strong herbs may have on the flavour

of your vegetables. Try to avoid placing two heavy feeders or two shallow rooted plant types near each

other.

Herb Companions Pests Repelled

Basil Tomatoes Flies, Mosquitoes

Dead Nettle

Chives Carrots

Potatoes Potato Bug

Dill CabbageDislikes Carrots

Garlic

Fennel Most plants dislike this herb

Roses, Raspberries Japanese Beetle, Aphids

Marigolds Plant throughout the garden Mexican Bean Beetles, Nematodes, others

MintCabbage, Tomatoes

White Cabbage Moth, aphids, flea beetles

Pot Marigold

Tomatoes Tomato Worm, Asparagus Beetles, others

Rosemary Cabbage, Beans Carrots, Sage Cabbage Moth, Bean Beetle, Carrot Fly

SageRosemary, Cabbage, Carrots

Dislikes Cucumbers

Cabbage Moth, Carrot Fly, Flea Beetle, Slugs

Thyme Cabbage Cabbage Worm

Companion planting practices

• The following are some examples of farming in the village of Cochrane where companion planting is practiced traditionally with herbs & vegetables

Herbs & vegetables plot #1

Farmer of plot

Extension Off. Examining plot

Vegetable plot #2

Asparagus & Flowers

Farmer harvesting crop

Compost pit

Farmer harvesting

Companion of cane & marigold

Harvest Time

• We have come to harvest time remember in organic planting always make certain you know what your companion crops are in the field, this will lead to reduce crop damage through pest & diseases.

• Remember organic farming is a process not a past time. Have fun.

Researched & compiled by Camille Researched & compiled by Camille LeblancLeblanc