When to plant Spinach in Idaho

In spring, from Feb 15 – Apr 1 in Lewiston to Apr 10 – June 15 in Garden City.

For a fall crop, from June 1 – Aug 1 in Rexburg to Sept 1 – Oct 1 in Lewiston.

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

Spinach planting dates by place in Idaho
PlaceSpringFall
AmmonApr 1 – June 15July 1 – Aug 15
BlackfootMar 20 – Apr 20July 1 – Aug 15
Boise CityMar 1 – Apr 15Aug 20 – Sept 10
BurleyApr 1 – June 15July 1 – Aug 15
CaldwellMar 20 – Apr 20Aug 1 – Sept 1
ChubbuckApr 10 – June 15July 1 – Aug 15
Coeur d'AleneMar 1 – Apr 15Aug 20 – Sept 10
EagleMar 20 – Apr 20Aug 20 – Sept 10
Garden CityApr 10 – June 15Aug 1 – Sept 1
HaydenMar 1 – Apr 15Aug 20 – Sept 10
Idaho FallsApr 1 – June 15July 1 – Aug 15
JeromeMar 20 – Apr 20Aug 1 – Sept 1
KunaMar 1 – Apr 15Aug 20 – Sept 10
LewistonFeb 15 – Apr 1Sept 1 – Oct 1
MeridianMar 1 – Apr 15Aug 20 – Sept 10
MiddletonMar 20 – Apr 20Aug 1 – Sept 1
MoscowMar 20 – Apr 20July 1 – Aug 15
Mountain HomeMar 20 – Apr 20Aug 1 – Sept 1
NampaMar 20 – Apr 20Aug 1 – Sept 1
PocatelloMar 20 – Apr 20Aug 1 – Sept 1
Post FallsMar 1 – Apr 15Aug 20 – Sept 10
RathdrumMar 1 – Apr 15Aug 20 – Sept 10
RexburgApr 1 – June 15June 1 – Aug 1
SandpointApr 1 – June 15July 1 – Aug 15
StarMar 20 – Apr 20Aug 1 – Sept 1
Twin FallsMar 20 – Apr 20Aug 1 – Sept 1

Planting dates: USDA Home and Garden Bulletin No. 9 (1967), tables 4 and 5. Frost dates: NOAA U.S. Climate Normals 1991–2020. The full USDA table for spinach.