Season Extension & Cold Frames

Compiled by EAC Staff, August 2014

Season extension & cold frames

Workshop facilitator notes

Sample workshop [1-1.5 hours] Compiled by Jen at the Ecology Action Centre “Flow of information”

Group introductions [5 min]

Season extension [5 min]

-Why do it?

-How to do it?

-The growing season, before and after

-Spring [5 min]

-Fall [10 min]

Examples and additional tips [5 min]

Engage:

Option 1: building a recycled window cold frame

[1 hour]

Option 2: planting in a pre-built cold frame [30

min]

Season Extension

Season extension means extending the traditional gardening

season- that is, extending the time a crop is normally able to

grow outdoors, or giving plants a head start before the season.

This is done by creating certain conditions for your plants that

allow them to grow before warm weather, and past the onset

of a colder season. Extending the season can include the use of

cold frames, row covers, and even grow-lights. In summary,

season extension is a way of gardening that allows you to make

the most out of the growing year.

What is the “growing season”?

The growing season length, according to “Climate Change NS” includes “The number of days between the dates when the mean daily temperature exceeds 5ºC.” Currently this includes approximately 200 days, and is expected to increase in number as climate change affects the region. The growing season tends to start somewhere around mid-April and ends in October. However, frost warnings are often in place up until the end of June, and again October 1. This is when frost-protection strategies come into play, as you will discover later on in this document.

Home Harvest, the “edible landscaping company,” based in

Halifax, designed a Planting Guide based on Nova Scotia’s

growing season. See Appendix A.

Before the season

Spring: “starting early”

A practice gardeners will use as a head start to the growing

season is starting seeds indoors before frost warnings lift. Many

people start seeds beginning in March, or

as early as February. Seed-starting indoors

requires a system of container trays,

potting mix, sufficient space, regular

watering, and lots of light. The light

source can either be natural or artificial.

Some people start seeds in a window that

gets a lot of sun. Larger-scale seed starting

may involve a heated or unheated

greenhouse.

Artificial lighting usually means using a grow-light. Grow-lights

are designed specifically for seed-starting and sometimes even

full plant growth. Using grow-light methods can be as simple as

using a fluorescent light bulb, or as elaborate as grow-light

plant stands (pictured). Lights can be purchased from Halifax

Seed, Lee Valley, hydroponics stores, or online.

Seeds need to be planted according to their needs (check the

package or online), and watered regularly to avoid drying out,

especially when they’re just sprouting. If you’re using a grow

light system, you’ll need to set a timer to give the plants

approximately 12 hours of light. Once seeds are established as

plants (usually with a few sets of leaves) and the growing

season has started, they can be transplanted outdoors into the

garden.

After the season

Fall: “growing beyond”

The keys to ensuring successful season extension include heat-

retention and frost-protection. From The Winter Harvest

Handbook by (Eliot Coleman), the three basic components to

winter harvest include: cold-hardy vegetables, succession

planting, and protected cultivation.

1) Learn the cold-hardy vegetables: the

ones that tolerate colder weathers and

have lower light requirements. This

includes spinach, swiss chard, carrots,

mache, lettuce, leeks minutina, arugula,

beet greens, raab, pak choi, kale,

parsley… to name a few! These

vegetables like cooler weather. Planting

some in Spring and again in August for a

Fall harvest is a great way to make the most of time in the

growing season. See the Appendix C for a full list of cold-hardy

vegetables.

2) Succession Planting: this is the process of planting things

continuously so that you can enjoy a constant bounty and a

nonstop, staggered harvest. Tips on planting vegetables at

intervals throughout the seasons include: a) Choosing season-

appropriate cultivars, b) the pick and sow method: picking and

then “seeding” every few weeks (starting new seeds), and c)

familiarizing yourself with the planting calendar.

3) Protected cultivation: this just

means plants under cover. In season

extension this includes row covers,

smaller hoop houses, greenhouse-size

tunnel hoop houses (pictured), or cold

frames, which act as a miniature

greenhouse.

Other tips & examples for extending

season:

raised beds: raised beds are more accessible, manageable,

and they heat up sooner in the springtime! They reduce

weeds and allow for better drainage and the development

of nutrient-rich soil, resulting in higher yields. It’s also easy

to attach a hoop house to a raised bed, or turn a raised

bed into a cold frame!

mulching: mulching regulates the temperature in beds,

supporting the plants during the season, and acting as a

“blanket” for plants over the winter. Mulching is a great

habit to get into- using hay or straw, woods chips, or dried

leaves works.

using a “cloche” or hot cap: this is any

material used as a protective covering to

shield plants. Ex. a plastic jug, an old

punch bowl, or a jar. Cloches may be

used early on in the season when there is

still risk of frost or cooler nights- for

example, protecting a newly-

transplanted tomato.

alternatives to cold frames: straw-

bale cold frame to protect winter

leeks/other tall vegetables ie. kale

and collards.

interplanting: similar to companion

planting, this is planting things to get the

most out of space by combining plants

which have different maturity dates, growth

patterns, and space needs in order to

maximize space.

Building a Cold Frame: Plan and Process

Recycled Window Cold Frame Construction

Introduction

The following guide will enable you to prepare a cold frame using rough cut lumber and a recycled window. The construction is intended to be simple, make use of easily accessible material, and be safe. Note: Lumber cuts are based on rough cut wood

Wood Required and Cuts:

(3) 12’ – 2x6: These will be cut to specifications within the Instructions section under

Window Measurements and Wood Cuts.

(1) 6’ – 2x2: (2) cut at 17” and (2) cut at 11”

Other Materials:

4” Hinges (2) recycled or new

Recycled exterior window with wooden frame

(10) #8 – 2” wood screws

(50) #10 – 3” wood screws

Tools Required:

Impact drill or screwdriver with square (#2) bit

Drill with 1/8” bit

Measuring tape

Carpenters square

Pencil

Circular saw or handsaw

Construction Plan:

1) Window Measurements and Wood Cuts

2) Back Frame Construction (1) & Front Frame Construction (1)

3) Frame Sides (2) Installation 4) Window and Hinge Installation

Instructions: 1. Window Measurements and Wood Cuts Measure the length and width of the window and record these measurements. With a circular or hand saw, cut five pieces of 2x6 at the same measurement as the width of the window. For the frame sides, cut six pieces of 2x6 four inches shorter than the length of the window, this will accommodate for the added width of the window frames during installation. For two of the frame side pieces, make a straight cut using a circular saw, hand saw or jig saw from one corner to the opposite corner in a diagonal fashion, thus creating a triangle (sloped piece) at the same length as the other frame side pieces. 2. Back Frame Construction (1) & Front Frame Construction (1)

For the back frame, lay three of the pieces cut to the window’s width on a flat surface; the

edges of each should be flush with each other and their longer edges abutted to one another.

With a measuring tape and carpenters

square or straight edge, draw a line

2” in from each end of these boards

so that the line is perpendicular to

the longer edges of each.

Lay two of the 17” pieces on these

boards aligned with each of the

previously drawn lines. Ensure that the

2x2s are flush on the edge of the 2x6 that

will be the bottom of the cold frame.

Prior to fastening these to the boards,

predrill two holes for each board within

the 2x2 to ensure the pieces do not split

when being fastened.

Fasten each 2x2 to the boards, keeping the outside edges of the 2x6s

flush; do this with the #10 – 3” wood screws. The front frame will be

completed in the same fashion but with the 11” 2x2 pieces as the connecting pieces.

When stood upright and facing each other from the inside the back and front frames should

look like this:

3. Frame Sides (2) Installation

Two 2x6 pieces will be stacked and fastened to the 2x2 pieces of both

the front and back frames. This can be done with the #10 – 3” wood

screws. With two stacked on each side, the third (sloped) 2x6 pieces

can be appended to the top of each frame side. The cut for the

sloped piece should extend from one corner of the 2x6 piece to the

opposite corner so as to create a triangle. A good way to make this

cut safely using a circular saw is to fasten one side of it to a wooden

surface, leaving the cut line clear of the surface so the saw will not

cut down into it. With the

piece fastened with at least

two screws at different

places, slowly cut the

diagonal.

Before fastening these sloped pieces of 2x6, predrill

two holes about 4” apart near the thinner end of

each piece so that the wood does not split during

drilling.

Front

Frame

Back

Frame

Fasten each to the 2x6s below with the #10 – 3” wood screws and then fasten the back end

of the sloped 2x6 to the back frame 2x2s to secure the piece in place.

Now that the overall frame is complete, the window can be fastened to the frame using

the hinges; ensure the frame looks like this before proceeding:

4. Window & Hinge Installation

Lay the window so that its edges align with the edges of

the cold frame.

At 5” from each edge of the upper 2x6 (back frame),

draw a line on both the 2x6 and window frame; this will

serve as a guide when installing the hinges.

Fasten each of the hinges to both

the back frame and the window

frame using #8 2” wood screws;

the hinges should have their outer

edges in line with the lines

previously drawn.

Now that the build is complete, it is good practice

to open and close the lid to see if there are any

issues with the hinges and to ensure the fit is snug.

In addition, we recommend that absorbent

material such as soft piping tubing or something

similar be appended to the edge of the sloped 2x6

so that contact between the window and cold

frame does not break the glass.

Back

Frame

Add Absorbent

Material Here

Placing the cold frame

Placement of the cold frame is important, in order to maximize

growing potential. The idea is to find a “micro-climate” on your

site. In this case, it’s the spot that is south-facing, and perhaps

warmest. Niki’s tip “a good indicator is: where the snow melts

first in your yard”

Activities for a group

Hand out planting calendars. Appendix A and B are examples of

growing calendars. Draw a theoretical garden. Have

participants pick out vegetables they’d like to see grown, and

then have them learn their growing times by referring to the

calendars. This will help to identify the cold-hardy vegetables,

which are ideal for the extended season (Fall and Winter

months). Then, make a “cold frame plan” with selected

vegetables.

If you have a cold frame available, plant it with either seeds or

transplants.

Resources

Halifax Garden Network: http://halifaxgardennetwork.com

Year-Round Vegetable Gardener- Niki Jabbour

The Winter Harvest Handbook – Eliot Coleman

Appendix A

Home Harvest Planting Guide

Appendix B

The Growing Calendar

Appendix C

Cool-tolerant vegetable charts