When to plant Cucumbers in Colorado

In spring, from Apr 20 – June 1 in Grand Junction to June 1 – 15 in Monument.

In fall, June 1 – July 1.

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

Cucumbers planting dates by place in Colorado
PlaceSpringFall
ArvadaMay 15 – June 15June 1 – July 1
AuroraMay 20 – June 15June 1 – July 1
BerthoudMay 20 – June 15June 1 – July 1
BoulderMay 20 – June 15June 1 – July 1
BrightonMay 15 – June 15June 1 – July 1
BroomfieldMay 15 – June 15June 1 – July 1
Cañon CityMay 15 – June 15June 1 – July 1
Castle PinesMay 20 – June 15June 1 – July 1
Castle RockMay 20 – June 15June 1 – July 1
CentennialMay 15 – June 15June 1 – July 1
Colorado SpringsMay 15 – June 15June 1 – July 1
Commerce CityMay 15 – June 15June 1 – July 1
DenverMay 15 – June 15June 1 – July 1
DurangoJune 1 – 15June 1 – July 1
EnglewoodMay 15 – June 15June 1 – July 1
ErieMay 20 – June 15June 1 – July 1
EvansMay 15 – June 15June 1 – July 1
Federal HeightsMay 15 – June 15June 1 – July 1
FirestoneMay 20 – June 15June 1 – July 1
Fort CollinsMay 15 – June 15June 1 – July 1
Fort MorganMay 20 – June 15June 1 – July 1
FountainMay 15 – June 15June 1 – July 1
FrederickMay 20 – June 15June 1 – July 1
FruitaMay 15 – June 15June 1 – July 1
Glenwood SpringsMay 20 – June 15June 1 – July 1
GoldenMay 15 – June 15June 1 – July 1
Grand JunctionApr 20 – June 1June 1 – July 15
GreeleyMay 15 – June 15June 1 – July 1
Greenwood VillageMay 20 – June 15June 1 – July 1
JohnstownMay 20 – June 15June 1 – July 1
LafayetteMay 15 – June 15June 1 – July 1
LakewoodMay 15 – June 15June 1 – July 1
LittletonMay 15 – June 15June 1 – July 1
Lone TreeMay 15 – June 15June 1 – July 1
LongmontMay 20 – June 15June 1 – July 1
LouisvilleMay 20 – June 15June 1 – July 1
LovelandMay 20 – June 15June 1 – July 1
MontroseMay 15 – June 15June 1 – July 1
MonumentJune 1 – 15June 1 – July 1
NorthglennMay 15 – June 15June 1 – July 1
ParkerMay 20 – June 15June 1 – July 1
PuebloMay 15 – June 15June 1 – July 1
RifleMay 20 – June 15June 1 – July 1
SeveranceMay 15 – June 15June 1 – July 1
Steamboat SpringsNot listedNot listed
SterlingMay 15 – June 15June 1 – July 1
SuperiorMay 20 – June 15June 1 – July 1
ThorntonMay 15 – June 15June 1 – July 1
TimnathMay 15 – June 15June 1 – July 1
WellingtonMay 15 – June 15June 1 – July 1
WestminsterMay 15 – June 15June 1 – July 1
Wheat RidgeMay 15 – June 15June 1 – July 1
WindsorMay 15 – June 15June 1 – July 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 cucumbers.