FrostCal

When to Plant Onions in Alaska

In a typical Alaska location, start seeds indoors Mar 7 – Mar 21, then transplant outdoors Apr 18 – May 2. Across the state, the outdoor planting window starts as early as Mar 7 in Ketchikan and as late as May 14 in Kalifornsky.

Method Start indoors, then transplant
Days to maturity 90–120 days

Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.

Onions Planting Dates by City

CityStart indoorsTransplant
AnchorageFeb 20 – Mar 6Apr 3 – Apr 17
FairbanksMar 7 – Mar 21Apr 18 – May 2
JuneauFeb 9 – Feb 23Mar 23 – Apr 6
Eagle RiverFeb 28 – Mar 14Apr 11 – Apr 25
BadgerMar 13 – Mar 27Apr 24 – May 8
Knik-FairviewMar 9 – Mar 23Apr 20 – May 4
CollegeMar 9 – Mar 23Apr 20 – May 4
WasillaMar 7 – Mar 21Apr 18 – May 2
SitkaFeb 22 – Mar 8Apr 5 – Apr 19
LakesMar 7 – Mar 21Apr 18 – May 2
KetchikanJan 24 – Feb 7Mar 7 – Mar 21
TanainaMar 7 – Mar 21Apr 18 – May 2
KalifornskyApr 2 – Apr 16May 14 – May 28
KenaiMar 15 – Mar 29Apr 26 – May 10
Meadow LakesMar 7 – Mar 21Apr 18 – May 2
PalmerFeb 25 – Mar 11Apr 8 – Apr 22
Elmendorf Air Force BaseFeb 28 – Mar 14Apr 11 – Apr 25
BethelMar 12 – Mar 26Apr 23 – May 7
KodiakFeb 18 – Mar 4Apr 1 – Apr 15
SterlingMar 11 – Mar 25Apr 22 – May 6

Showing the 20 most populous of 20 Alaska cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Alaska cities.

Frequently Asked Questions

When should I plant onions in Alaska?

In a typical Alaska location, start seeds indoors Mar 7 – Mar 21, then transplant outdoors Apr 18 – May 2. Across the state, the outdoor planting window starts as early as Mar 7 in Ketchikan and as late as May 14 in Kalifornsky.

When is the last frost in Alaska?

The average last spring frost in Alaska ranges from April 4 in Ketchikan to June 11 in Kalifornsky, based on NOAA 1991–2020 climate normals.

How long do onions take to grow?

Onions typically take 90–120 days from planting to harvest. Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.

Other Crops in Alaska

When to plant onions in other states

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