Hardiness Zones and Why You Should Know Yours when Planning Your Garden


In Sudbury, Ontario, where our farm is located, we are in a hardiness zone of 4A (although sometimes it can feel like a 3B). What does this mean?

Plant Hardiness Zones in Canada indicate the areas where various trees, shrubs and flowers are most likely to survive. There are nine zones (0-8), and these zones are calculated based on average climatic conditions and altitude of each area. The harshest zone is 0 and the mildest is 8. Each major zone is divided into subzones “a” and “b” (for example 3a and 3b) where zone a is slightly harsher than zone b. Keep in mind that the United States Department of Agriculture has its own Zone map that has 11 Zones. Depending on where you buy your seed, sometimes you will see Zones above 8 listed, in which case you know they will be referring to the USDA Zone map which is widely available with a general web-search.


Using low tunnels that provide additional protection from the elements can be beneficial for the Northern Gardener and can extend your harvests into the winter for some hardy crops photo from yourbeautyadvisor.com


Why does knowing your plant hardiness zone matter?

Knowing your region’s hardiness zone will help you understand which varieties of vegetables/fruits/flowers to grow. If you have about 100 Frost Free Days, knowing that this can vary from season to season, you may want to purchase seeds that are 90-100 days to maturity or less. For example, in the Sudbury Region, many serious food growers wait until June 10th to plant out anything frost sensitive, and they anticipate that the first frost may arrive the first week of September.

Home gardeners have the benefit of micro-climates (i.e. windbreaks or thermal heat from a wall, a raised bed etc.) that may allow them to take a risk and plant before June 10th, knowing they may have to cover their plants should a frost threaten. Home gardeners in this region might be able to get away with a variety of crop that takes 105-110 days to mature, but it is advisable to stick with shorter season crops if you want to make sure that your harvests are plentiful (and that your winter-squash ripen!) Keep in mind that some seed companies list their Days to Maturity for a specific crop to be from the day you transplant your seedling into the garden, rather than total days to maturity. This is something to consider if you are growing crops that need to be 3-12 weeks old by the time they are transplanted to the garden, (i.e. eggplants, peppers, tomatoes, celery, celeriac, squash, etc.)

Using row cover can protect frost-sensitive crops from unexpected frosts at the beginning and end of the growing season. photo from organiccatalague.com

Here is an average of expected Days to Maturity on a crop-by-crop basis. Keep in mind that there will be variation depending on the specific variety for each crop.

  • Peas (all kinds)- 55- 85 Days
  • Beets- 50-70 Days
  • Broccoli- 50-65 Days
  • Cabbage- 60-90 Days
  • Carrots 60-80 Days
  • Cucumbers- 50-65 Days
  • Eggplants 75-90 Days (from transplant)
  • Lettuce- 21 Days for baby greens, 45-60 Days for Heads
  • Melons (watermelon, cantaloupe) 75-100 Days (transplants recommended for short seasons)
  • Okra- 50-65 Days
  • Parsnips- 100-130 Days (definitely try to get short season varieties, but they can take a frost)
  • Onions 100-120 Days (transplant recommended)
  • Peppers 60-90 Days (from transplant)
  • Potatoes- 90-120 Days
  • Pumpkins & other Winter Squash- 85-120 Days (transplant recommended)
  • Beans (fresh beans)- 50-70 Days
  • Spinach 45-60 Days
  • Zucchini & other summer squash- 50-60 Days (transplant recommended)
  • Sweet Corn- 70-105 Days (try for short season corn when possible)
  • Tomato- 70-90 Days (from transplant)
  • Sweet Potato- 100-125 Days (could be hard to grow in a Northern Climate but worth a shot if you have a micro-climate!)

Planning and planting for your region’s hardiness zone will lead to more fruitful harvests! If you can find regionally adapted seed, meaning seed grown in your region, or in an area that has a similar zone to yours (even if it does have to come from a different country or province) then this is even better!! Check out our great selection of vegetable, fruit, and flower seeds that are supportive of more Northern Climates!!



1 comment

  • Still trying to figure out how to protect my vegetables in pots and in ground plus my black currant bushes. Difficult to protect when the night go down to plus 2 or 3 and sometimes go as low as 0 and its May. How does one protect 2 black currant bushes in full flowers and night temperature goes down to freezing? You loose your flowers so there goes my fruit. The bushes are 5 feet high and 10 feet wide. They are side by side.


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