Garden Growing Zones

Garden Growing Zones

By Mark Cullen

Sometimes in our efforts to make things easy, we make them complicated.

You could say this is true of growing zones in Canada. These are arbitrary, segments of the country that have been sectioned off in an effort to create a guide for what plants grow where, according to winter hardiness.

Truth is, growing zones are not complicated when you understand a few basic principles. Here is our primer:

  1. The higher the number, the higher the temperature. Canada ranges between zone 9 (southwestern British Columbia and the southern tip of Vancouver Island) and zone 0 in the Arctic. Knowing what growing zone you live in is a useful tool when plant shopping and swapping.
  2. Growing zones are not determined simply based on temperature (average low) though, that is a big part of it. Agriculture Canada, the people responsible for our zone map, determines growing zones based on a formula that includes prevailing winds, length of growing season and average winter temperature.
  3. It is a guide. As many experienced gardeners will tell you, our growing zone map can be cheated. That is, you can create micro-climates around your home by avoiding wind and harnessing the free energy of the sun.  some prairie gardeners live in zone 2 but have figured out how to plant zone 3 hardy plants successfully. 
    You can achieve this using fences, hedges and your house to avoid prevailing winds. Planting on a southern slope takes advantage of solar energy as can the south and east side of your home.
  4. When you are shopping for plants look carefully at the label for the growing zone. A zone that matches or is lower than your own indicates that the plant will likely survive in your garden.
  5. We garden in zone 5: not quite as cold as Ottawa or Montreal (zone 4) but colder than Toronto (zone 6). By planting in a protected place we have succeeded in planting many “zone 6” plants in our garden for many years.


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