GreenlyHelsinki: frost dates
Finland
In Helsinki the last spring frost usually comes around 6 May and the first autumn frost around 20 October, which leaves about 167 frost-free days (median of 2016–2025). Tomato seedlings can go into open ground around 2 June.
| Last spring frost | around 6 May |
|---|---|
| First autumn frost | around 20 October |
| Frost-free days | 167 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 | 14 March | 27 May | 17 June |
| Chili Pepper | 22 March | 4 June | 25 June |
| Corn | — | 28 April | sow 19 May |
| Cucumber | 15 April | 27 May | 17 June |
| Eggplant | 18 March | 27 May | 17 June |
| Green Beans | 22 March | 28 April | 19 May |
| Melon | 5 April | 27 May | 17 June |
| Peas | — | 25 March | sow 15 April |
| Physalis | 28 March | 12 May | 2 June |
| Pumpkin | 5 April | 12 May | 2 June |
| Sweet Corn | — | 28 April | sow 19 May |
| Tomato | 16 March | 12 May | 2 June |
| Watermelon | 25 April | 27 May | 17 June |
| Zucchini | 10 April | 12 May | 2 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.
Helsinki: 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 | 20 September |
| Daffodil | 20 September |
| Garlic | 20 September |
| Hyacinth | 20 September |
| Lily | 20 September |
| Tulip | 20 September |
A month before the first autumn frost, so the roots grow before winter.