Alberta Vegetable Planting Calendar (Edmonton, Calgary, Red Deer)

Alberta gardens work with one of the shortest and most variable seasons in southern Canada. Edmonton averages about 123 frost-free days, the Calgary area closer to 100, and Fort McMurray around 70. That spread is why a single provincial planting date does not work.

This calendar lists average frost dates for Alberta cities, then turns them into suggested dates for starting seeds indoors, sowing outdoors and transplanting.

The short answer

• Most of Alberta sees its average last spring frost between mid- and late May, and the first fall frost in early to mid-September.
• Cool crops like peas, spinach and carrots can go in during early to mid-May; tomatoes, peppers and squash wait until late May or early June.
• Start tomatoes indoors in mid-April and peppers in late March to early April.

Average frost dates in Alberta

Location (climate station)	Average last spring frost	Average first fall frost	Frost-free days
Edmonton (Edmonton City Centre)	May 15	Sep 16	123
Calgary area (Madden)	May 29	Sep 6	99
Red Deer	May 24	Sep 10	108
Grande Prairie	May 22	Sep 6	106
Lethbridge	May 25	Sep 11	108
Medicine Hat	May 18	Sep 14	118
Fort McMurray	Jun 15	Aug 26	71

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.

Alberta planting calendar

Suggested dates for four Alberta centres, based on the frost dates above:

Task	Edmonton	Calgary area	Red Deer	Grande Prairie
Start onions and leeks indoors	Mar 20	Apr 3	Mar 29	Mar 27
Start peppers indoors	Mar 30	Apr 13	Apr 8	Apr 6
Start broccoli and cabbage indoors	Apr 7	Apr 21	Apr 16	Apr 14
Start tomatoes indoors	Apr 13	Apr 27	Apr 22	Apr 20
Sow peas, spinach, lettuce, radishes outdoors (soil workable, ~10°C for peas)	May 1	May 15	May 10	May 8
Sow carrots and beets outdoors	May 5	May 19	May 14	May 12
Plant potatoes (soil above ~7°C)	May 15	May 29	May 24	May 22
Transplant broccoli and cabbage (nights above −2°C)	May 18	Jun 1	May 27	May 25
Sow beans (soil at least 15°C)	May 22	Jun 5	May 31	May 29
Transplant tomatoes and peppers	May 25	Jun 8	Jun 3	Jun 1
Transplant or sow cucumbers, squash, pumpkins (days and nights 18°C+)	May 29	Jun 12	Jun 7	Jun 5
Last sowing of bush beans for a fall crop	Jul 18	Jul 8	Jul 12	Jul 8
Last sowing of spinach and leaf lettuce	Aug 2	Jul 23	Jul 27	Jul 23
Last sowing of radishes	Aug 17	Aug 7	Aug 11	Aug 7

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 Alberta gardens

• Expect late frosts. A frost in early June is common enough that tender transplants should always have a cover ready.
• Use the warm spots. South-facing walls and city yards can gain several days at each end of the season.
• Choose short-season varieties. Tomatoes and peppers that finish in about 70 days or less are the safest bet. See tomatoes for zone 3.
• Warm the soil with plastic for a week or two before planting heat-loving crops: how to warm soil in spring.

Frequently Asked Questions

When should I plant my garden in Edmonton?

With an average last frost around May 15, sow cool crops like peas and spinach in early May and transplant tomatoes and peppers around May 25, once nights stay mild.

When should I plant tomatoes in Calgary?

Using the Madden station average last frost of May 29, transplant tomatoes around June 8. City gardens often warm up a little earlier. Start seeds indoors in late April.

When do I start seeds indoors in Alberta?

For Edmonton, start onions around March 20, peppers in late March, broccoli and cabbage in early April and tomatoes in mid-April. Shift later for colder areas.

How long is the growing season in Alberta?

Roughly 100 to 125 frost-free days in the south and central parts of the province, and about 70 in Fort McMurray.

Sources

• The Old Farmer’s Almanac – Frost dates
• University of Saskatchewan Gardenline – Vegetables
• University of Minnesota Extension – Planting vegetables in midsummer for a fall harvest