Seed Starting Calendar for Alaska

Count back from the median last frost where you garden. At Anchorage (Anchorage Merrill Field) that date is May 1, so for spring 2027 onions start indoors Jan 23 to Feb 6, peppers Mar 6 to Mar 20 and tomatoes Mar 13 to Mar 27. Across Alaska's 145 NOAA stations the median last frost runs from Apr 20 to Jun 5 for the middle 90 percent, so a garden near Cooper Landing 5 W starts later than one near Annette Island Airport.

It depends on the station. The earliest median last spring freeze in Alaska is April 4 at Annette Island Airport; the latest is June 12 at Cooper Landing 5 W. A median is a coin flip: at Anchorage the last 32°F freeze comes after May 1 in half of years, and has passed by May 9 in 9 of 10 years (NOAA 1991 to 2020 normals).

UNH Extension sets tomatoes out 1 to 2 weeks after the last frost, which at Anchorage is May 8 to May 15 in 2027. Tomatoes are frost tender, so the date to watch is May 9, when 9 of 10 springs at Anchorage have had their last 32°F night. Hardening off starts two weeks before setting out (Apr 24 to May 8).

University of Alaska Fairbanks Cooperative Extension Service's Seed Starting & Transplanting puts it this way: "Subtract the number of weeks listed from the average date of the last spring frost in your locality to determine planting dates." The guide is linked below with the date it was read (September 21, 2026).

UNH Extension gives 8 to 10 weeks from seed to transplant for both, and sets peppers out 2 weeks after the last frost and eggplant 2 to 3 weeks after, so the sowing date is 6 to 8 weeks before the median last frost. At Anchorage that is Mar 6 to Mar 20 for peppers.

About two weeks. University of Missouri Extension: "Hardening should be started about two weeks before planting in the garden." University of Minnesota Extension adds that seedlings should go out on a cloudy day or in the late afternoon.

Juneau's maritime spring reaches its median last frost around Apr 20, Anchorage around May 1 and Fairbanks around May 13, while Nome waits until about Jun 5, so Interior seeds start weeks later than Southeast ones. Each station carries its own dates: Juneau Apr 20 and Nome Municipal Airport Jun 5 at the median.