When to plant Spinach in Colorado

In spring, from Feb 15 – Apr 1 in Grand Junction to May 1 – June 15 in Steamboat Springs.

In fall, from June 1 – July 15 in Steamboat Springs to Aug 20 – Sept 10 in Grand Junction.

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 Colorado
PlaceSpringFall
ArvadaMar 20 – Apr 20July 1 – Aug 15
AuroraApr 1 – June 15Aug 1 – Sept 1
BerthoudApr 1 – June 15July 1 – Aug 15
BoulderApr 1 – June 15July 1 – Aug 15
BrightonMar 20 – Apr 20Aug 1 – Sept 1
BroomfieldMar 20 – Apr 20Aug 1 – Sept 1
Cañon CityMar 20 – Apr 20Aug 1 – Sept 1
Castle PinesApr 1 – June 15July 1 – Aug 15
Castle RockApr 1 – June 15July 1 – Aug 15
CentennialMar 20 – Apr 20Aug 1 – Sept 1
Colorado SpringsMar 20 – Apr 20Aug 1 – Sept 1
Commerce CityMar 20 – Apr 20Aug 1 – Sept 1
DenverMar 20 – Apr 20Aug 1 – Sept 1
DurangoApr 10 – June 15July 1 – Aug 15
EnglewoodMar 20 – Apr 20Aug 1 – Sept 1
ErieApr 1 – June 15July 1 – Aug 15
EvansMar 20 – Apr 20Aug 1 – Sept 1
Federal HeightsMar 20 – Apr 20Aug 1 – Sept 1
FirestoneApr 1 – June 15July 1 – Aug 15
Fort CollinsMar 20 – Apr 20Aug 1 – Sept 1
Fort MorganApr 1 – June 15Aug 1 – Sept 1
FountainMar 20 – Apr 20Aug 1 – Sept 1
FrederickApr 1 – June 15July 1 – Aug 15
FruitaMar 20 – Apr 20Aug 1 – Sept 1
Glenwood SpringsApr 1 – June 15July 1 – Aug 15
GoldenMar 20 – Apr 20Aug 1 – Sept 1
Grand JunctionFeb 15 – Apr 1Aug 20 – Sept 10
GreeleyMar 20 – Apr 20Aug 1 – Sept 1
Greenwood VillageApr 1 – June 15Aug 1 – Sept 1
JohnstownApr 1 – June 15July 1 – Aug 15
LafayetteMar 20 – Apr 20Aug 1 – Sept 1
LakewoodMar 20 – Apr 20Aug 1 – Sept 1
LittletonMar 20 – Apr 20Aug 1 – Sept 1
Lone TreeMar 20 – Apr 20Aug 1 – Sept 1
LongmontApr 1 – June 15July 1 – Aug 15
LouisvilleApr 1 – June 15July 1 – Aug 15
LovelandApr 1 – June 15July 1 – Aug 15
MontroseMar 20 – Apr 20Aug 1 – Sept 1
MonumentApr 10 – June 15July 1 – Aug 15
NorthglennMar 20 – Apr 20Aug 1 – Sept 1
ParkerApr 1 – June 15July 1 – Aug 15
PuebloMar 20 – Apr 20Aug 1 – Sept 1
RifleApr 1 – June 15July 1 – Aug 15
SeveranceMar 20 – Apr 20Aug 1 – Sept 1
Steamboat SpringsMay 1 – June 15June 1 – July 15
SterlingMar 20 – Apr 20Aug 1 – Sept 1
SuperiorApr 1 – June 15July 1 – Aug 15
ThorntonMar 20 – Apr 20Aug 1 – Sept 1
TimnathMar 20 – Apr 20Aug 1 – Sept 1
WellingtonMar 20 – Apr 20Aug 1 – Sept 1
WestminsterMar 20 – Apr 20Aug 1 – Sept 1
Wheat RidgeMar 20 – Apr 20July 1 – Aug 15
WindsorMar 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. “—” means the place's frost date is outside the table. The full USDA table for spinach.