GreenlyCalgary: frost dates
Canada
In Calgary the last spring frost usually comes around 13 May and the first autumn frost around 1 October, which leaves about 141 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground around 3 June.
| Last spring frost | around 13 May |
|---|---|
| First autumn frost | around 1 October |
| Frost-free days | 141 days |
Median of 2016–2025 for the 25 km grid cell of the city: the last day at or below 0 °C in spring and the first in autumn (ERA5 reanalysis via Open-Meteo). In a cold year a frost can come a week or two later — Greenly warns 48 hours ahead.
When to sow and plant
| Crop | Sow for seedlings | Plant out in a greenhouse | Open ground |
|---|---|---|---|
| Bell Pepper | 15 March | 28 May | 18 June |
| Chili Pepper | 5 April | 18 June | 9 July |
| Corn | — | 29 April | sow 20 May |
| Cucumber | 16 April | 28 May | 18 June |
| Eggplant | 19 March | 28 May | 18 June |
| Green Beans | 23 March | 29 April | 20 May |
| Melon | 6 April | 28 May | 18 June |
| Peas | — | 1 April | sow 22 April |
| Physalis | 29 March | 13 May | 3 June |
| Pumpkin | 6 April | 13 May | 3 June |
| Sweet Corn | — | 29 April | sow 20 May |
| Tomato | 17 March | 13 May | 3 June |
| Watermelon | 26 April | 28 May | 18 June |
| Zucchini | 11 April | 13 May | 3 June |
Planting out: a week after the last frost once the soil is warm enough for the crop; frost-hardy crops three weeks before it; an unheated greenhouse three weeks earlier. Seedlings are sown so they are ready on that day.
Calgary: weather for the next 7 days
Forecast by Open-Meteo. Nights at or below 0 °C are marked as frost.
Planted in autumn
| Crop | Plant around |
|---|---|
| Crocus | 1 September |
| Daffodil | 1 September |
| Garlic | 1 September |
| Hyacinth | 1 September |
| Lily | 1 September |
| Tulip | 1 September |
A month before the first autumn frost, so the roots grow before winter.