When to plant Onion sets in Washington

In spring, from Jan 1 – Mar 1 in Burien to May 1 – 30 in Cheney.

In fall, from May 1 – June 1 in Cheney to Nov 1 – Dec 31 in Woodinville.

USDA's earliest safe spring and latest safe fall planting dates, matched to each place's average frost dates.

Onion sets planting dates by place in Washington
PlaceSpringFall
AberdeenFeb 15 – Mar 20Oct 1 – Dec 1Now
Airway HeightsMar 10 – Apr 10Spring-planted
AnacortesJan 15 – Mar 10Nov 1 – Dec 31Soon
ArlingtonMar 10 – Apr 1Spring-planted
AuburnFeb 1 – Mar 20Oct 1 – Dec 1Now
Bainbridge IslandFeb 15 – Mar 20Oct 1 – Dec 1Now
Battle GroundMar 10 – Apr 10Spring-planted
BellevueJan 15 – Mar 10Nov 1 – Dec 31Soon
BellinghamFeb 15 – Mar 20Not listed
Bonney LakeMar 1 – Apr 1Not listed
BothellJan 15 – Mar 10Nov 1 – Dec 31Soon
BremertonFeb 15 – Mar 20Oct 1 – Dec 1Now
BurienJan 1 – Mar 1Nov 1 – Dec 31Soon
BurlingtonFeb 1 – Mar 20Not listed
CamasFeb 1 – Mar 20Nov 1 – Dec 31Soon
CentraliaMar 10 – Apr 1Not listed
CheneyMay 1 – 30May 1 – June 1
CovingtonMar 10 – Apr 1Spring-planted
Des MoinesJan 1 – Mar 1Nov 1 – Dec 31Soon
East WenatcheeFeb 15 – Mar 20Not listed
EdgewoodJan 15 – Mar 10Oct 1 – Dec 1Now
EdmondsJan 15 – Mar 10Nov 1 – Dec 31Soon
EllensburgApr 10 – May 1Spring-planted
EnumclawMar 1 – Apr 1Not listed
EverettFeb 1 – Mar 20Not listed
Federal WayJan 15 – Mar 10Oct 1 – Dec 1Now
FerndaleFeb 15 – Mar 20Not listed
FifeJan 15 – Mar 10Oct 1 – Dec 1Now
Gig HarborJan 15 – Mar 10Nov 1 – Dec 31Soon
GrandviewMar 10 – Apr 10Spring-planted
IssaquahJan 15 – Mar 10Nov 1 – Dec 31Soon
KelsoMar 1 – Apr 1Oct 1 – Dec 1Now
KenmoreJan 15 – Mar 10Nov 1 – Dec 31Soon
KennewickFeb 15 – Mar 20Not listed
KentFeb 1 – Mar 20Oct 1 – Dec 1Now
KirklandJan 15 – Mar 10Nov 1 – Dec 31Soon
LaceyMar 10 – Apr 10Spring-planted
Lake Forest ParkJan 15 – Mar 10Nov 1 – Dec 31Soon
Lake StevensFeb 1 – Mar 20Not listed
LakewoodJan 15 – Mar 10Nov 1 – Dec 31Soon
Liberty LakeMar 10 – Apr 10Spring-planted
LongviewMar 1 – Apr 1Oct 1 – Dec 1Now
LyndenMar 10 – Apr 1Spring-planted
LynnwoodJan 15 – Mar 10Nov 1 – Dec 31Soon
Maple ValleyMar 10 – Apr 1Spring-planted
MarysvilleFeb 1 – Mar 20Not listed
Mercer IslandJan 15 – Mar 10Nov 1 – Dec 31Soon
Mill CreekJan 15 – Mar 10Nov 1 – Dec 31Soon
MonroeMar 10 – Apr 1Spring-planted
Moses LakeMar 10 – Apr 10Spring-planted
Mount VernonFeb 1 – Mar 20Not listed
Mountlake TerraceJan 15 – Mar 10Nov 1 – Dec 31Soon
MukilteoJan 15 – Mar 10Nov 1 – Dec 31Soon
NewcastleJan 15 – Mar 10Nov 1 – Dec 31Soon
Oak HarborJan 15 – Mar 10Oct 1 – Dec 1Now
OlympiaMar 10 – Apr 10Spring-planted
PascoMar 10 – Apr 10Spring-planted
Port AngelesJan 15 – Mar 10Nov 1 – Dec 31Soon
Port OrchardFeb 15 – Mar 20Oct 1 – Dec 1Now
Port TownsendJan 1 – Mar 1Nov 1 – Dec 31Soon
PoulsboFeb 15 – Mar 20Oct 1 – Dec 1Now
PullmanApr 10 – May 1Spring-planted
PuyallupMar 1 – Apr 1Not listed
RedmondJan 15 – Mar 10Nov 1 – Dec 31Soon
RentonJan 15 – Mar 10Nov 1 – Dec 31Soon
RichlandMar 1 – Apr 1Spring-planted
RidgefieldMar 10 – Apr 10Spring-planted
SammamishFeb 15 – Mar 20Oct 1 – Dec 1Now
SeaTacJan 1 – Mar 1Nov 1 – Dec 31Soon
SeattleJan 15 – Mar 10Nov 1 – Dec 31Soon
Sedro-WoolleyFeb 15 – Mar 20Oct 1 – Dec 1Now
SheltonMar 10 – Apr 10Spring-planted
ShorelineJan 15 – Mar 10Nov 1 – Dec 31Soon
SnohomishFeb 1 – Mar 20Not listed
SnoqualmieFeb 15 – Mar 20Oct 1 – Dec 1Now
SpokaneMar 10 – Apr 10Spring-planted
Spokane ValleyMar 10 – Apr 10Spring-planted
SumnerMar 1 – Apr 1Not listed
SunnysideMar 10 – Apr 10Spring-planted
TacomaJan 15 – Mar 10Oct 1 – Dec 1Now
TukwilaJan 1 – Mar 1Nov 1 – Dec 31Soon
TumwaterMar 10 – Apr 10Spring-planted
University PlaceJan 15 – Mar 10Nov 1 – Dec 31Soon
VancouverFeb 15 – Mar 20Oct 1 – Dec 1Now
Walla WallaFeb 15 – Mar 20Not listed
WashougalFeb 15 – Mar 20Nov 1 – Dec 31Soon
WenatcheeFeb 15 – Mar 20Not listed
West RichlandMar 1 – Apr 1Spring-planted
WoodinvilleJan 15 – Mar 10Nov 1 – Dec 31Soon
YakimaMar 1 – Apr 1Spring-planted
YelmMar 10 – Apr 10Spring-planted

Planting dates: USDA Home and Garden Bulletin No. 9 (1967), tables 4 and 5. Frost dates: NOAA U.S. Climate Normals 1991–2020. “—” means the place's frost date is outside the table. The full USDA table for onion sets.