GreenlyOttawa: frost dates
Canada
In Ottawa the last spring frost usually comes around 30 April and the first autumn frost around 1 November, which leaves about 185 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground around 27 May.
| Last spring frost | around 30 April |
|---|---|
| First autumn frost | around 1 November |
| Frost-free days | 185 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 |
|---|---|---|---|
| Achocha | 12 March | 21 April | 12 May |
| Arugula | — | 19 March | sow 9 April |
| Basil | 13 April | 21 May | 11 June |
| Beet | — | 19 March | sow 9 April |
| Bell Pepper | 8 March | 21 May | 11 June |
| Black-eyed Susan | 11 March | — | 12 May |
| Bok Choy | 17 March | 21 April | 12 May |
| Broad bean | — | 19 March | sow 9 April |
| Broccoli | — | 19 March | sow 9 April |
| Brussels Sprouts | 2 February | 19 March | 9 April |
| Cabbage | — | 19 March | sow 9 April |
| Calendula | — | 19 March | sow 9 April |
| Carrot | — | — | sow 9 April |
| Cauliflower | 5 February | 19 March | 9 April |
| Celeriac | 3 February | 21 April | 12 May |
| Celery | 3 February | 21 April | 12 May |
| Celosia | 26 March | 10 May | 31 May |
| Chamomile | — | 19 March | sow 9 April |
| Chayote | 29 January | 27 April | 18 May |
| Chickpea | — | — | sow 9 April |
| Chili Pepper | 21 March | 3 June | 24 June |
| China aster | 30 March | 21 May | 11 June |
| Chives | — | — | sow 9 April |
| Cilantro | — | 19 March | sow 9 April |
| Corn | — | 27 April | sow 18 May |
| Cosmos | 26 March | 10 May | 31 May |
| Cucumber | 9 April | 21 May | 11 June |
| Daikon | — | 19 March | sow 9 April |
| Delphinium | 9 February | — | 9 April |
| Dill | — | 19 March | sow 9 April |
| Eggplant | 12 March | 21 May | 11 June |
| Florence fennel | 7 March | 21 April | 12 May |
| Garden sorrel | — | 19 March | sow 9 April |
| Green Beans | 21 March | 27 April | 18 May |
| Hyssop | — | — | sow 9 April |
| Kale | — | 19 March | sow 9 April |
| Kiwano | 4 April | 6 May | 27 May |
| Kohlrabi | — | 19 March | sow 9 April |
| Leek | 8 January | 19 March | 9 April |
| Lemon balm | — | 19 March | sow 9 April |
| Lettuce | — | 19 March | sow 9 April |
| Lisianthus | 22 December | 19 March | 9 April |
| Lovage | — | — | sow 9 April |
| Luffa | 9 April | 21 May | 11 June |
| Marigold | 10 March | 21 April | 12 May |
| Melon | 30 March | 21 May | 11 June |
| Microgreens | — | 10 May | sow 31 May |
| Moringa | 9 April | 3 June | 24 June |
| Mustard greens | — | 19 March | sow 9 April |
| Napa cabbage | 19 March | 21 April | 12 May |
| Nasturtium | 14 March | 21 April | 12 May |
| Okra | 9 April | 21 May | 11 June |
| Oregano | 18 January | 19 March | 9 April |
| Pansy | 22 January | 19 March | 9 April |
| Parsley | — | 19 March | sow 9 April |
| Parsnip | — | — | sow 9 April |
| Peanut | 14 April | 21 May | 11 June |
| Peas | — | 19 March | sow 9 April |
| Petunia | 19 March | 21 May | 11 June |
| Physalis | 22 March | 6 May | 27 May |
| Pumpkin | 30 March | 6 May | 27 May |
| Purple coneflower | 6 February | — | 9 April |
| Radish | — | — | sow 9 April |
| Sage | 29 January | 19 March | 9 April |
| Snapdragon | 13 January | 19 March | 9 April |
| Spinach | — | 19 March | sow 9 April |
| Stevia | 18 March | 6 May | 27 May |
| Stock | — | 19 March | sow 9 April |
| Sunflower | — | 10 May | sow 31 May |
| Sweet Corn | — | 27 April | sow 18 May |
| Sweet pea | 5 February | 19 March | 9 April |
| Sweet William | — | — | sow 9 April |
| Swiss Chard | — | 19 March | sow 9 April |
| Thyme | — | 19 March | sow 9 April |
| Tomato | 10 March | 6 May | 27 May |
| Turnip | — | 19 March | sow 9 April |
| Watercress | — | 19 March | sow 9 April |
| Watermelon | 19 April | 21 May | 11 June |
| Zinnia | 29 April | 3 June | 24 June |
| Zucchini | 4 April | 6 May | 27 May |
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.
Ottawa: 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 |
|---|---|
| Bearded Iris | 2 October |
| Crocus | 2 October |
| Daffodil | 2 October |
| Garlic | 2 October |
| Hyacinth | 2 October |
| Lily | 2 October |
| Peony | 2 October |
| Saffron | 2 October |
| Tulip | 2 October |
| Wild garlic | 2 October |
A month before the first autumn frost, so the roots grow before winter.