Gardening in Zone 3 can be tricky and often full of risk. The last frost date in the spring is typically around May 16 – 25 and the first frost in the fall is often September 10-20. This makes the growing season rather short, and there is a good chance Mother Nature will throw a curve ball or two and make it even shorter! Because of this, starting seeds inside is essential if you want to grow any type of warm weather vegetable in zone 3. Determining your planting dates can help you schedule your winter and spring seed starting.
Zone 3 Seed Starting
Maturity Dates
Starting seeds in zone 3 indoors is often the only way that certain plants will reach maturity in our short growing season. When reading the back of a seed packet, make sure to note the days to maturity. If the number of days is longer than your growing season (about 108 days in zone 3), you’ll have to get set up to start some seeds in the warmth of your home – or be willing to purchase seedlings from a greenhouse.
Germination Dates
Germination dates detail how many days it takes for a seed to sprout and develop its first true leaves. Some seeds may take three weeks while others take even longer.
Using the germination and maturity dates can help determine if a plant should be started indoors as well as help you to plan your harvest schedule. If you want to harvest carrots and peas at the same time to make a bag of frozen mixed vegetables, you’ll have to count backwards from the anticipated harvest date to the date which you’ll need to seed either plant.
Seeds can often be grouped into 3 categories:
Cold hardy; these seeds can be started very early (beginning to mid-March) or six weeks prior to transplanting outside.
Kale, broccoli, and brussels sprouts
Hot weather; these plants need to be started inside and hardened off in the spring so they have time to adapt to our spring temperatures versus the constant climate of our homes. Plan on seeding these plants March 7 to April 1st. However, some of these will have such a long germination time that they may need to be started even earlier. Make sure to read the back of the seed packet.
Tomatoes, peppers
- Fast-growing warm weather crops; these should be started outside after the last frost date, or started indoors just a couple weeks before the last frost and then transplanted.
Cucumbers, zucchini, squash, melons
There is a fourth bonus category that many Zone 3 gardeners will take full advantage of; fast-growing, cool-weather crops. This group mainly consists of tubers such as carrots, beets, radishes, and potatoes. All of these can be planted outdoors after the last frost. Except for potatoes, most gardeners can usually get two harvests from these guys. One mid-summer, and another in the fall by planting a succession crop just before the first is harvested. Find out which plants can be planted in July!
Indoor Planting Dates for Zone 3 Gardening
January 14 - 21
lavender
leeks
mint
onions from seed
pansies
rosemary
sage
If you're starting your herbs indoors in January, expect them to be full-sized and ready to harvest by June.
February 14 - 21
Celery
oregano
parsley
peppers (read more on my guide to starting peppers from seed)
rudbeckia
March 1 - 7
marigolds (these can also be planted in the spring, but they won't bloom until about August)
tomatoes (if you don't have space to transplant these into bigger pots, wait 3 more weeks to seed them)
snapdragons
March 21 - 28
Bok Choy
broccoli
brussels sprouts
cabbage
cauliflower
April 21 - 28
cucumbers
squash
melons
zucchini
Consider planting these in fibre pots and removing the bottom at transplanting or plant in soil blocks since their roots don't like to be disturbed.
When spring arrives, make sure you harden off your plants prior to transplanting them into the ground to prevent them from dying of shock.
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