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Nord-Koster
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Growing Season: Nord-Koster

Västra Götaland, Sweden

Growing season

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 12 Jun
Daylight
10+ h
14+ h
10+ h
27 Feb
13 Apr
30 Aug
14 Oct
229 days
Frost-free
10% frost-free
30 Mar
20 Nov
90% frost risk
235 days
Effective
30 Mar
14 Oct
198 days

The growing season in Nord-Koster is approximately 198 days and is limited by both frost and daylight.

Last spring frost

The last spring frost normally occurs on 30 Mar in Nord-Koster. At the earliest, the last frost is over around 19 Mar and at the latest around 14 Apr.

Frost-free probabilityFrost-free prob. Date Grower's risk level Explanation
10% 19 Mar High risk Frost 9 out of 10 years after this date
25% 21 Mar Frost 3 out of 4 years after this date
50% 30 Mar Normal risk Frost every other year after this date
75% 7 Apr Frost 1 out of 4 years after this date
90% 14 Apr 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 Nord-Koster that is 30 Mar. 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 20 Nov in Nord-Koster. At the earliest, frost can arrive around 4 Nov and at the latest around 1 Dec.

Frost probabilityFrost prob. Date Grower's risk level Explanation
10% 4 Nov Low risk Frost 1 out of 10 years on or before this date
25% 14 Nov Frost 1 out of 4 years on or before this date
50% 20 Nov Normal risk Frost every other year on or before this date
75% 27 Nov Frost 3 out of 4 years on or before this date
90% 1 Dec 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 Nord-Koster that is 20 Nov. 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 27 Feb 14 Oct 229
Persephone period 15 Oct 26 Feb 136
Plan the year's last sowing of cold-hardy plants in Nord-Koster so they are approximately 75% mature by 15 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 27 Feb – 12 Apr 45 Grow long-day plants like spinach, lettuce and coriander.
Longer daylight 14+ h 13 Apr – 29 Aug 139 High risk of bolting
Shorter daylight 10-14 h 30 Aug – 14 Oct 46 Grow long-day plants