It seems like an inhospitable place for growing, but some northern gardeners practically thrive in cold climates. Even with short summers and long winters, they’re still producing food. How? They use season extension.

Whether you live in the frigid north or in a climate with four distinct seasons, season extension can help you grow more food, even when the weather isn’t cooperating. Today, as part of our Grow More Food blog series, we will examine three different aspects of season extension: seedlings, fall gardening, and season extension structures.

macro, nursery, plants

Image from Pixabay via Pexels

Grow More Food by Starting Seedlings

Starting seedlings indoors and then transplanting them outside is the best way to produce more food, especially in climates with shorter growing seasons.

First, you need some basic supplies.

  • Seeds
  • Containers
  • Growing medium


There are three different types of seeds: heirloom seeds, hybrid seeds, and GMO seeds. A hybrid is a variety that is a hand-pollinated cross between two varieties and will not breed true from parent to child. An heirloom is a variety that is genetically stable and will bred true from parent to child. You should prefer heirloom seeds over hybrid or genetically engineered seeds.


There are many containers for growing seedlings, but 1020 trays (10” x 20”) are most common. You can also experiment with other products like peat pots and soil block makers.

Growing Medium

You need a growing medium for your seedlings, either a pre-made mix, a homemade mix, or a pre-made mix that you amend yourself.

Germination Requirements

Seeds can be picky when it comes to germination. Do they need light or dark? Heat or cold? Soaking? Scarification? Germination requirements should be listed on the seed packets.

To sprout, seedlings need a nearby heat source like a furnace or a heating mat.

Also, seedlings need to be kept moist. Most seeds require constant moisture for germination.

And finally, seedlings need light, such as indirect sunlight from a window or light from fluorescent shop lights or commercial grow lights.

Hardening Off Plants

Before you can plant seedlings outdoors, you must first “harden” them. “Hardening” occurs when your plants become accustomed to the outdoor variances in temperatures and wind speeds and exposure to strong, direct sunlight.  Failing to do this can cause your plants to struggle or even die.

Start with a location sheltered from the wind and direct midday sun. (A cold frame or a metal frame with Plexiglas can be a good start.)

Gradually, increase your plants’ sunlight exposure and decrease their protection from nighttime cold. Eventually, your seedlings will be used to this new outside world and will be ready to plant.

Transplanting…in Season Extension?

Learn more about transplanting as a method of season extension by watching this clip from “Garden Planning to Feed Your Family”.

autumn, leaves, ground

Image from Pixabay via MorningbirdPhoto

Grow More Food with Fall Gardening

Fall might seem like an odd time to grow food, but it can be a surprisingly productive time to grow, if you consider these important factors.

  1. Soil
  2. Location
  3. Space & Irrigation
  4. Sunlight
  5. Temperature
  6. Season Length & Frost Dates


When you’re growing food, your soil needs high organic matter and pH balance. Sandy loam is ideal, but if your soil is subpar, just add organic matter as you plant.

Fall is the perfect time to start building soil for the upcoming season, and planting a cover crop or putting mulch down is far better than doing nothing to your space. A proper clover will grow through the mulch, and you can get the best of both worlds. If you have growing space, that space should always be in use, even in cooler weather. (And yes, a cover crop is a use.)


When planning a fall garden location, sunlight and wind are the primary determinants. Later in the year, the angle of the sun changes and shade might become an issue. Plants need that sun for heat. In addition, wind can drop temperatures significantly, so use windbreakers like trees, fence lines, and hardy plants.

With the shade and wind, keep in mind that a north-facing plot will cool off earlier.

Space & Irrigation

Your total space available is the sum of all the plots’ area. In equation form, it looks like this:

Plot = L * W of plot – total square foot of internal paths

In addition to considering your space availability, consider your ability to irrigate in colder weather. Know how much water you will need and how far the water is from your plants. If you’re growing past the frost, don’t forget about those hoses and pipes!


Like we mentioned before, sunlight is more important as temperatures cool, because sunlight is the primary heat source for your plants. Soil with more sun stays warm the longest and south- to southwest-facing slopes are warmest.


While the warm temps might be good for summer crops, some crops mature better in cooler temperatures. Examples of such crops include peas, spinach, lettuce, and Asian greens, crops that will usually bolt too quickly in the spring.

Also, be aware that as temps drop, plant growth slows. You must adjust timing for fall plantings accordingly.

Season Length & Frost Dates

If you grow food in the fall, you must understand your season dates, particularly your Last Average Spring Frost and First Average Fall Frost dates. These dates will determine your growing season, as season length is the difference between those two frost dates (FAFF-LASF). (To find these dates, check online and with neighbors and your local ag extension.)

These dates will also help you determine your lead times.

You can use an excellent Fall Planting Calculator from Seeds for Generations that will give you planting dates when you enter your First Fall Frost Date, and makes determining these really easy.

mini greenhouse, lettuce, vegetable

Image from Pixabay via titosoft

Grow More Food Using Season Extension Structures

A very impressive season extension method, structures like greenhouses and cold frames are fantastic ways to extend your growing season.


What is the difference between a greenhouse (also called high tunnel) and other forms of season extension?  Most consider the difference being that you can walk into a greenhouse.  You will see both commercial and homemade greenhouses.

Cold Frames

Cold frames are an anti-frost and heating method which, like greenhouses, can be commercial or homemade models. Try adding some thermal mass to help stabilize the temperatures in cold frames and greenhouses; fill 5 gallon jugs with water dyed from black walnut husks. Even just a couple jugs will increase your thermal mass and heat collected from the sun and increase the frost protection.

Low Tunnels

Low tunnels are made from plastic or white-colored fabric over hoops.

Watch Mike Brabo discuss low tunnels in this clip from “Greenhouse Production”.


Traditionally, a cloche is a bell-shaped glass enclosure used for protecting plants. You can use a plastic jug with the bottom cut out, glass jars, or plastic containers saved from salad mixes as homemade cloches. Whatever your container choice, ventilation is a must.


Even if it’s cold outside, you can grow more food yourself by utilizing fall gardening, seedlings, and season extension structures.

Put that produce to good use. Create your own ferments!

This free CHEAT SHEET helps you "create-your-own" simple, and safe-to-eat, and delicious fermented salsas, chutneys, pickles, or krauts!

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