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Svartbyn
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Growing Season: Svartbyn

Boden, Norrbotten, Sweden
-1.5°
Last 24h: Slight frost recorded tonight at 02:00. Inspect for frost damage
No frost in sight Last frost normally in 10 days (19 May), but frost-free in the forecast.

Growing season

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 9 May
Daylight
10+ h
14+ h
10+ h
5 Mar
8 Apr
5 Sep
8 Oct
217 days
Frost-free
10% frost-free
19 May
14 Sep
90% frost risk
118 days
Effective
19 May
14 Sep
118 days

The growing season in Svartbyn is approximately 118 days and is limited by frost.

Last spring frost

The last spring frost normally occurs on 19 May in Svartbyn. At the earliest, the last frost is over around 9 May and at the latest around 5 Jun.

Frost-free probabilityFrost-free prob. Date Grower's risk level Explanation
10% 9 May High risk Frost 9 out of 10 years after this date
25% 16 May Frost 3 out of 4 years after this date
50% 19 May Normal risk Frost every other year after this date
75% 25 May Frost 1 out of 4 years after this date
90% 5 Jun Low risk Frost 1 out of 10 years after this date
Growing is often planned around the date when there is a 50% probability that the last spring frost has occurred. In Svartbyn that is 19 May. If you want lower frost risk, choose 75% or 90%, i.e. a later date.

First autumn frost

The first autumn frost normally occurs on 14 Sep in Svartbyn. At the earliest, frost can arrive around 29 Aug and at the latest around 25 Sep.

Frost probabilityFrost prob. Date Grower's risk level Explanation
10% 29 Aug Low risk Frost 1 out of 10 years on or before this date
25% 2 Sep Frost 1 out of 4 years on or before this date
50% 14 Sep Normal risk Frost every other year on or before this date
75% 18 Sep Frost 3 out of 4 years on or before this date
90% 25 Sep High risk Frost 9 out of 10 years on or before this date
Growing is often planned around the date when there is a 50% probability that the first autumn frost has occurred. In Svartbyn that is 14 Sep. If you want lower frost risk, choose 10% or 25%, i.e. an earlier date.

Daylight & Persephone Period

Plants need at least 10 hours of daylight to grow actively. The period with under 10 h is called the Persephone period.

From To Number of days
Daylight over 10 h 5 Mar 8 Oct 217
Persephone period 9 Oct 4 Mar 148
Plan the year's last sowing of cold-hardy plants in Svartbyn so they are approximately 75% mature by 9 Oct when daylight drops below 10 h and growth starts to slow.

Daylight periods

Long-day plants like lettuce, spinach and coriander bolt when daylight gets too long. Plan sowing and harvest during periods when daylight is shorter (10-14 h). Early spring or late summer sowing gives the best results.

Season Light Period Days Advice
Shorter daylight 10-14 h 5 Mar – 7 Apr 34 Grow long-day plants like spinach, lettuce and coriander.
Longer daylight 14+ h 8 Apr – 4 Sep 150 High risk of bolting
Shorter daylight 10-14 h 5 Sep – 8 Oct 34 Grow long-day plants