Calgary frost dates and planting season

Name: Calgary
Address: Alberta, Canada

When to plant vegetables here. Cover calendars (fleece, cold frame, unheated greenhouse) are on each plant’s when-to-plant page.

Calgary has a moderate growing season, with roughly 153 frost-free days between the typical frost dates. Typical last spring frost: around May 12 (half of years later). Typical first fall frost: around October 13. Plant cool-season crops after about May 25; wait until about June 29 for warm-season crops.

Frost-free days153May 12 – Oct 13

Frost-free season in Calgary. Based on average frost dates. Adjust a week or two for your conditions.

Cover calendars (fleece, cold frame, unheated greenhouse) live on each crop’s when-to-plant page.

Weekly possible temperature−43 – 36 °C

Frost-free days153

Typical last spring frostMay 12

Typical first fall frostOctober 13

Days suitable for warm-season vegetables70 (June 29 – September 6)

Days suitable for cool-season vegetables133 (May 25 – October 4)

Calculated by Plan & Plant · Method · Data 2019–2026

Frost and suitability dates are typical figures from climate statistics. Microclimates vary; they are not a guarantee.

Frost dates calculated by Plan & Plant from Weather data by Open-Meteo.com (CC BY 4.0). Local frost pockets, valleys and coastal sites can differ by 1–3 weeks.

How we calculated this

Data: ERA5-Land via Open-Meteo, cell 51.00, -114.10, years 2019–2026 (not a 30-year climate normal yet).
Typical and safer dates: Typical last frost is the date after which half of winters in this sample had no more frost; safer is later in the sample so fewer winters still frosted.
Confidence: Provisional — short or thin sample for this place.
Full methodology (algorithm 2026-10-season-6).

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What to plant when

Cool-season vegetables

Earliest outdoor start: May 25

Suitable window: May 25 – October 4

Cool-season crops prefer cooler weather.

See cool-season details

Warm-season vegetables

Earliest outdoor start: June 29

Suitable window: June 29 – September 6

Warm-season crops need mild or warm weather and cannot take frost.

Frost kills these crops, and cold snaps set them back.

See warm-season details

Green = usually good weeks to grow; blue or gray = usually too cold for that crop type.

Starter plants for Calgary

Cool-season

Radish Sow: April 23 – August 28 Planting dates
Arugula Sow: April 23 – August 15 Planting dates
Spinach Sow: April 15 – August 8 Planting dates
Lettuce Sow: April 15 – August 3 Planting dates
Kale Sow: April 23 – June 17 Planting dates
Beet Sow: April 23 – July 15 Planting dates

Warm-season

No warm-season starters fit this place.

How these dates are judged

Last frost: The typical last spring date when frost is still expected.
First frost: The typical first fall date when frost returns.
Frost-free days: The approximate days between those two dates.
Cool-season vegetables: Crops that prefer cooler weather, such as lettuce, kale, peas, and radish.
Warm-season vegetables: Crops that need warm weather and cannot take frost, such as tomato, pepper, squash, and beans.

Cool-season planting window

May 25 – Oct 4 (133 days)

Warm-season planting window

Jun 29 – Sep 6 (70 days)

Usually too cold

January 1 – May 24
October 5 – December 31

Weekly temperatures and planting windows

Temperatures across the year for Calgary, with cool- and warm-season weeks and frost dates.

Possible min to max
Average min to max
Suitable
Tolerable
Too cold
Too hot

Selected week · tap a week or use the arrows

Week 22 · May 25 – May 31

Average 7 to 20 °C · Possible 1 to 30 °C

Cool season: tolerable

Warm season: too cold

A week is suitable for a crop type when its average low and high sit inside that type's range and its possible readings stay within the frost and heat limits (cool: −2 °C to 27 °C, warm: 0 °C to 32 °C); crossing a limit makes it tolerable, and for warm crops any chance of frost makes it too cold.

Based on average frost dates.

Alberta, Canada · 51, -114.1 · 2026

Coldest weekly possible temperature−43 °C

Hottest weekly possible temperature36 °C

Last expected spring frostMay 12

First expected fall frostOctober 13

Show all 53 weeks