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Älvkarleby
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Growing Season: Älvkarleby

Älvkarleby, Uppsala, Sweden
0.6°
Last 24h: Near frost recorded tonight at 05:00. Inspect for frost damage

Growing season

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 9 May
Daylight
10+ h
14+ h
10+ h
1 Mar
12 Apr
31 Aug
13 Oct
226 days
Frost-free
10% frost-free
6 May
6 Oct
90% frost risk
153 days
Effective
6 May
6 Oct
153 days

The growing season in Älvkarleby is approximately 153 days and is limited by frost.

Last spring frost

The last spring frost normally occurs on 6 May in Älvkarleby. At the earliest, the last frost is over around 25 Apr and at the latest around 15 May.

Frost-free probabilityFrost-free prob. Date Grower's risk level Explanation
10% 25 Apr High risk Frost 9 out of 10 years after this date
25% 1 May Frost 3 out of 4 years after this date
50% 6 May Normal risk Frost every other year after this date
75% 12 May Frost 1 out of 4 years after this date
90% 15 May 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 Älvkarleby that is 6 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 6 Oct in Älvkarleby. At the earliest, frost can arrive around 30 Sep and at the latest around 20 Oct.

Frost probabilityFrost prob. Date Grower's risk level Explanation
10% 30 Sep Low risk Frost 1 out of 10 years on or before this date
25% 1 Oct Frost 1 out of 4 years on or before this date
50% 6 Oct Normal risk Frost every other year on or before this date
75% 12 Oct Frost 3 out of 4 years on or before this date
90% 20 Oct 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 Älvkarleby that is 6 Oct. 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 1 Mar 13 Oct 226
Persephone period 14 Oct 28 Feb 139
Plan the year's last sowing of cold-hardy plants in Älvkarleby so they are approximately 75% mature by 14 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 1 Mar – 11 Apr 42 Grow long-day plants like spinach, lettuce and coriander.
Longer daylight 14+ h 12 Apr – 30 Aug 141 High risk of bolting
Shorter daylight 10-14 h 31 Aug – 13 Oct 44 Grow long-day plants