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Indal
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Growing Season: Indal

Sundsvall, Västernorrland, Sweden
0.2°
Last 24h: Near frost recorded tonight at 05:00. Inspect for frost damage
No frost in sight Last frost normally in 9 days (18 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
3 Mar
10 Apr
2 Sep
11 Oct
222 days
Frost-free
10% frost-free
18 May
30 Sep
90% frost risk
135 days
Effective
18 May
30 Sep
135 days

The growing season in Indal is approximately 135 days and is limited by frost.

Last spring frost

The last spring frost normally occurs on 18 May in Indal. At the earliest, the last frost is over around 8 May and at the latest around 30 May.

Frost-free probabilityFrost-free prob. Date Grower's risk level Explanation
10% 8 May High risk Frost 9 out of 10 years after this date
25% 13 May Frost 3 out of 4 years after this date
50% 18 May Normal risk Frost every other year after this date
75% 22 May Frost 1 out of 4 years after this date
90% 30 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 Indal that is 18 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 30 Sep in Indal. At the earliest, frost can arrive around 11 Sep and at the latest around 14 Oct.

Frost probabilityFrost prob. Date Grower's risk level Explanation
10% 11 Sep Low risk Frost 1 out of 10 years on or before this date
25% 22 Sep Frost 1 out of 4 years on or before this date
50% 30 Sep Normal risk Frost every other year on or before this date
75% 7 Oct Frost 3 out of 4 years on or before this date
90% 14 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 Indal that is 30 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 3 Mar 11 Oct 222
Persephone period 12 Oct 2 Mar 143
Plan the year's last sowing of cold-hardy plants in Indal so they are approximately 75% mature by 12 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 3 Mar – 9 Apr 38 Grow long-day plants like spinach, lettuce and coriander.
Longer daylight 14+ h 10 Apr – 1 Sep 145 High risk of bolting
Shorter daylight 10-14 h 2 Sep – 11 Oct 40 Grow long-day plants