When to plant Summer squash (zucchini) in Idaho

In spring, from Apr 20 – June 1 in Lewiston to May 20 – June 15 in Garden City.

In fall, from May 15 – July 1 in Rexburg to June 1 – July 15 in Twin Falls.

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

Summer squash planting dates by place in Idaho
PlaceSpringFall
AmmonMay 10 – June 10June 1 – July 1
BlackfootMay 1 – 30June 1 – July 1
Boise CityMay 1 – June 15June 1 – July 20
BurleyMay 10 – June 10June 1 – July 1
CaldwellMay 1 – 30June 1 – July 15
ChubbuckMay 20 – June 15June 1 – July 1
Coeur d'AleneMay 1 – June 15June 1 – July 20
EagleMay 1 – 30June 1 – July 20
Garden CityMay 20 – June 15June 1 – July 15
HaydenMay 1 – June 15June 1 – July 20
Idaho FallsMay 10 – June 10June 1 – July 1
JeromeMay 1 – 30June 1 – July 15
KunaMay 1 – June 15June 1 – July 20
LewistonApr 20 – June 1June 1 – Aug 1
MeridianMay 1 – June 15June 1 – July 20
MiddletonMay 1 – 30June 1 – July 15
MoscowMay 1 – 30June 1 – July 1
Mountain HomeMay 1 – 30June 1 – July 15
NampaMay 1 – 30June 1 – July 15
PocatelloMay 1 – 30June 1 – July 15
Post FallsMay 1 – June 15June 1 – July 20
RathdrumMay 1 – June 15June 1 – July 20
RexburgMay 10 – June 10May 15 – July 1
SandpointMay 10 – June 10June 1 – July 1
StarMay 1 – 30June 1 – July 15
Twin FallsMay 1 – 30June 1 – July 15

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 summer squash.