FrostCal

When to Plant Onions in Washington

In a typical Washington location, start seeds indoors Jan 13 – Jan 27, then transplant outdoors Feb 24 – Mar 10. Across the state, the outdoor planting window starts as early as Feb 1 in Port Townsend and as late as May 2 in Cheney.

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
SeattleJan 2 – Jan 16Feb 13 – Feb 27
Tri-CitiesFeb 16 – Mar 2Mar 30 – Apr 13
SpokaneFeb 15 – Mar 1Mar 29 – Apr 12
TacomaDec 28 – Jan 11Feb 8 – Feb 22
VancouverJan 18 – Feb 1Mar 1 – Mar 15
BellevueDec 28 – Jan 11Feb 8 – Feb 22
KentJan 9 – Jan 23Feb 20 – Mar 6
EverettJan 13 – Jan 27Feb 24 – Mar 10
RentonJan 2 – Jan 16Feb 13 – Feb 27
Federal WayDec 28 – Jan 11Feb 8 – Feb 22
Spokane ValleyFeb 15 – Mar 1Mar 29 – Apr 12
YakimaFeb 27 – Mar 13Apr 10 – Apr 24
KirklandDec 28 – Jan 11Feb 8 – Feb 22
BellinghamJan 21 – Feb 4Mar 4 – Mar 18
KennewickJan 17 – Jan 31Feb 28 – Mar 14
AuburnJan 9 – Jan 23Feb 20 – Mar 6
PascoJan 17 – Jan 31Feb 28 – Mar 14
MarysvilleJan 13 – Jan 27Feb 24 – Mar 10
RedmondDec 28 – Jan 11Feb 8 – Feb 22
LakewoodDec 31 – Jan 14Feb 11 – Feb 25
OlympiaFeb 18 – Mar 4Apr 1 – Apr 15
ShorelineDec 28 – Jan 11Feb 8 – Feb 22
RichlandJan 26 – Feb 9Mar 9 – Mar 23
South HillJan 31 – Feb 14Mar 14 – Mar 28
SammamishDec 28 – Jan 11Feb 8 – Feb 22
BurienDec 22 – Jan 5Feb 2 – Feb 16
LaceyFeb 18 – Mar 4Apr 1 – Apr 15
City of SammamishJan 19 – Feb 2Mar 2 – Mar 16
BothellDec 28 – Jan 11Feb 8 – Feb 22
EdmondsDec 29 – Jan 12Feb 9 – Feb 23

Showing the 30 most populous of 133 Washington cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Washington cities.

Frequently Asked Questions

When should I plant onions in Washington?

In a typical Washington location, start seeds indoors Jan 13 – Jan 27, then transplant outdoors Feb 24 – Mar 10. Across the state, the outdoor planting window starts as early as Feb 1 in Port Townsend and as late as May 2 in Cheney.

When is the last frost in Washington?

The average last spring frost in Washington ranges from March 1 in Port Townsend to May 30 in Cheney, 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 Washington

When to plant onions in other states

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