Manitoba Vegetable Planting Calendar (Winnipeg, Brandon and More)
Manitoba’s gardening season is short but warm. Around Winnipeg and Portage la Prairie the frost-free season averages about 115 to 120 days; Brandon and Dauphin are closer to 90 to 100, and Thompson under 60.
The short answer
- Around Winnipeg the average last spring frost is about May 21, and the first fall frost about mid-September.
- Western and northern Manitoba run later in spring and earlier in fall.
- Sow cool crops in early to mid-May and plant out tomatoes and peppers around the end of May or early June.
Average frost dates in Manitoba
| Location (climate station) | Average last spring frost | Average first fall frost | Frost-free days |
|---|---|---|---|
| Winnipeg area (Stony Mountain) | May 21 | Sep 15 | 116 |
| Portage la Prairie (Southport) | May 22 | Sep 19 | 119 |
| Brandon | Jun 6 | Sep 7 | 92 |
| Dauphin | Jun 1 | Sep 11 | 101 |
| Steinbach | Jun 2 | Sep 12 | 101 |
| The Pas | May 31 | Sep 15 | 106 |
| Thompson | Jun 18 | Aug 16 | 58 |
Frost dates from The Old Farmer’s Almanac (Environment Canada 1981–2010 normals, 33% probability threshold). The station used is named where it is outside the city. Full list for other cities: average frost dates for Canadian cities.
Manitoba planting calendar
| Task | Winnipeg area | Portage la Prairie | Brandon | Dauphin |
|---|---|---|---|---|
| Start onions and leeks indoors | Mar 26 | Mar 27 | Apr 11 | Apr 6 |
| Start peppers indoors | Apr 5 | Apr 6 | Apr 21 | Apr 16 |
| Start broccoli and cabbage indoors | Apr 13 | Apr 14 | Apr 29 | Apr 24 |
| Start tomatoes indoors | Apr 19 | Apr 20 | May 5 | Apr 30 |
| Sow peas, spinach, lettuce, radishes outdoors (soil workable, ~10°C for peas) | May 7 | May 8 | May 23 | May 18 |
| Sow carrots and beets outdoors | May 11 | May 12 | May 27 | May 22 |
| Plant potatoes (soil above ~7°C) | May 21 | May 22 | Jun 6 | Jun 1 |
| Transplant broccoli and cabbage (nights above −2°C) | May 24 | May 25 | Jun 9 | Jun 4 |
| Sow beans (soil at least 15°C) | May 28 | May 29 | Jun 13 | Jun 8 |
| Transplant tomatoes and peppers | May 31 | Jun 1 | Jun 16 | Jun 11 |
| Transplant or sow cucumbers, squash, pumpkins (days and nights 18°C+) | Jun 4 | Jun 5 | Jun 20 | Jun 15 |
| Last sowing of bush beans for a fall crop | Jul 17 | Jul 21 | Jul 9 | Jul 13 |
| Last sowing of spinach and leaf lettuce | Aug 1 | Aug 5 | Jul 24 | Jul 28 |
| Last sowing of radishes | Aug 16 | Aug 20 | Aug 8 | Aug 12 |
How these dates were worked out
Each date is counted from the local average frost dates above, using timing from the University of Saskatchewan Gardenline vegetable guides, which are written for prairie conditions:
- Onions and leeks are started indoors at least 8 weeks before the last frost; peppers about 8 weeks and tomatoes about 6 weeks before they go outside; broccoli and cabbage 5 to 6 weeks before.
- Peas, carrots and beets are sown 1 to 2 weeks before the last frost, once the soil is workable (peas want about 10°C).
- Potatoes go in when the soil passes about 7°C, usually around the last frost.
- Broccoli and cabbage transplants go out when nights stay above about −2°C.
- Beans are sown on or after the last frost, once the soil reaches about 15°C.
- Tomatoes and peppers go out 1 to 2 weeks after the last frost; cucumbers, squash and pumpkins about 2 weeks after, when days and nights reach about 18°C.
- Fall sowings are counted back from the first fall frost using typical days to maturity: about 45 to 65 days for bush beans, 35 to 45 for spinach and under a month for radishes (University of Minnesota Extension).
Treat every date as a starting point. Check the soil, watch the 7-day forecast, and move tender plants out later in a cold spring. Hardening off for about a week first is essential; see how to harden off seedlings.
Fall planting: garlic
Garlic is planted in fall, between late August and early October and up to about three weeks before the ground freezes, then mulched with 10 to 15 cm of straw. Details in when to plant garlic in Canada.
Tips for Manitoba gardens
- The May long weekend is not a frost-free guarantee. Around Winnipeg the average last frost falls after it, so keep covers handy for tender transplants.
- Squash and pumpkins need every warm day. Start them indoors 2 to 3 weeks before planting out and use plastic mulch.
- Use season extension: row covers and soil warming make a real difference in a 100-day season.
Gear that helps
- Seed starting trays with humidity domes: Domes hold moisture until seeds sprout; pick trays with drainage holes.
- LED grow light for seedlings: A window alone is too dim in a northern March or April. Keep the light a few centimetres above the plants.
- Frost cloth plant covers: Gives a few degrees of protection on cold spring and fall nights. Remove or vent it on warm days.
- Soil thermometer: Soil temperature, not the calendar, tells you when seeds will actually sprout.
As an Amazon Associate, Short Season Grower earns from qualifying purchases. Links open Amazon search results so you can compare brands, sizes and prices.
Frequently Asked Questions
When is the last frost in Winnipeg?
Using the Stony Mountain station just north of the city, the average last spring frost is around May 21 and the first fall frost around September 15.
Is the May long weekend safe for planting in Manitoba?
For hardy crops, usually. For tomatoes, peppers and squash it is often too early; the average last frost around Winnipeg falls after the long weekend.
When do I start tomato seeds in Manitoba?
About six weeks before transplanting. For the Winnipeg area that means around April 19 for a late-May or early-June planting.
How long is the growing season in Brandon?
Based on Environment Canada normals for Brandon, about 92 frost-free days, from early June to early September.
