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Jan Mayen
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Growing Season: Jan Mayen

Norway

Growing season

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 9 Jun
Daylight
10+ h
14+ h
10+ h
9 Mar
4 Apr
9 Sep
4 Oct
209 days
Frost-free
10% frost-free
9 Jun
29 Sep
90% frost risk
112 days
Effective
9 Jun
29 Sep
112 days

The growing season in Jan Mayen is approximately 112 days and is limited by frost.

Last spring frost

The last spring frost normally occurs on 9 Jun in Jan Mayen. At the earliest, the last frost is over around 29 May and at the latest around 15 Jun.

Frost-free probabilityFrost-free prob. Date Grower's risk level Explanation
10% 29 May High risk Frost 9 out of 10 years after this date
25% 6 Jun Frost 3 out of 4 years after this date
50% 9 Jun Normal risk Frost every other year after this date
75% 13 Jun Frost 1 out of 4 years after this date
90% 15 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 Jan Mayen that is 9 Jun. 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 29 Sep in Jan Mayen. At the earliest, frost can arrive around 16 Sep and at the latest around 11 Oct.

Frost probabilityFrost prob. Date Grower's risk level Explanation
10% 16 Sep Low risk Frost 1 out of 10 years on or before this date
25% 19 Sep Frost 1 out of 4 years on or before this date
50% 29 Sep Normal risk Frost every other year on or before this date
75% 6 Oct Frost 3 out of 4 years on or before this date
90% 11 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 Jan Mayen that is 29 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 9 Mar 4 Oct 209
Persephone period 5 Oct 8 Mar 156
Plan the year's last sowing of cold-hardy plants in Jan Mayen so they are approximately 75% mature by 5 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 9 Mar – 3 Apr 26 Grow long-day plants like spinach, lettuce and coriander.
Longer daylight 14+ h 4 Apr – 8 Sep 158 High risk of bolting
Shorter daylight 10-14 h 9 Sep – 4 Oct 26 Grow long-day plants