When to plant cucumbers in Colorado

Cucumbers
Plant out in Denver
May 18–May 25

Across Colorado the window opens between April 28 and May 24. Find your city below; the dates follow each town's own average last frost.

Start indoors, Denver
Apr 6–Apr 13
Plant out, Denver
May 18–May 25
Sow outdoors, Denver
May 11–May 25
Last sowing for a harvest
Jul 16
Last frost, Denver
May 4

Start seeds indoors 3–4 weeks before the last frost; plant out 2–3 weeks after the last frost; sow outdoors 1–3 weeks after the last frost. Cucumbers rot in cold soil. Sow when the soil is at least 65°F.

Cucumbers planting dates by city

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
JanFebMarAprMayJunJulAugSepOctNovDec
DenverMay 18–May 25
Colorado SpringsMay 17–May 24
AuroraMay 21–May 28
Fort CollinsMay 16–May 23
LakewoodMay 17–May 24
ThorntonMay 16–May 23
ArvadaMay 19–May 26
WestminsterMay 16–May 23
GreeleyMay 16–May 23
PuebloMay 14–May 21
CentennialMay 19–May 26
BoulderMay 20–May 27
LongmontMay 21–May 28
LovelandMay 24–May 31
BroomfieldMay 16–May 23
Commerce CityMay 17–May 24
Grand JunctionApr 28–May 5
LittletonMay 16–May 23
BrightonMay 17–May 24
WindsorMay 17–May 24
ErieMay 21–May 28
NorthglennMay 16–May 23
Security-WidefieldMay 17–May 24
EnglewoodMay 16–May 23
Pueblo WestMay 10–May 17
Wheat RidgeMay 19–May 26
LafayetteMay 16–May 23
FountainMay 17–May 24
EvansMay 16–May 23
JohnstownMay 24–May 31
All 34 cities
CityStart indoorsPlant outSow outdoorsLast frost
DenverApr 6 to Apr 13May 18 to May 25May 11 to May 25May 4
Colorado SpringsApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
AuroraApr 9 to Apr 16May 21 to May 28May 14 to May 28May 7
Fort CollinsApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
LakewoodApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
ThorntonApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
ArvadaApr 7 to Apr 14May 19 to May 26May 12 to May 26May 5
WestminsterApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
GreeleyApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
PuebloApr 2 to Apr 9May 14 to May 21May 7 to May 21Apr 30
CentennialApr 7 to Apr 14May 19 to May 26May 12 to May 26May 5
BoulderApr 8 to Apr 15May 20 to May 27May 13 to May 27May 6
LongmontApr 9 to Apr 16May 21 to May 28May 14 to May 28May 7
LovelandApr 12 to Apr 19May 24 to May 31May 17 to May 31May 10
BroomfieldApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
Commerce CityApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
Grand JunctionMar 17 to Mar 24Apr 28 to May 5Apr 21 to May 5Apr 14
LittletonApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
BrightonApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
WindsorApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
ErieApr 9 to Apr 16May 21 to May 28May 14 to May 28May 7
NorthglennApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
Security-WidefieldApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
EnglewoodApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
Pueblo WestMar 29 to Apr 5May 10 to May 17May 3 to May 17Apr 26
Wheat RidgeApr 7 to Apr 14May 19 to May 26May 12 to May 26May 5
LafayetteApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
FountainApr 5 to Apr 12May 17 to May 24May 10 to May 24May 3
EvansApr 4 to Apr 11May 16 to May 23May 9 to May 23May 2
JohnstownApr 12 to Apr 19May 24 to May 31May 17 to May 31May 10
Four Square MileApr 9 to Apr 16May 21 to May 28May 14 to May 28May 7
MontroseMar 31 to Apr 7May 12 to May 19May 5 to May 19Apr 28
LouisvilleApr 8 to Apr 15May 20 to May 27May 13 to May 27May 6
FirestoneApr 9 to Apr 16May 21 to May 28May 14 to May 28May 7

Questions

When should I plant cucumbers in Colorado?

In Denver, plant out from May 18 to May 25. Across Colorado the window opens between April 28 and May 24, depending on the local last frost.

How is this date worked out?

Start seeds indoors 3–4 weeks before the last frost; plant out 2–3 weeks after the last frost; sow outdoors 1–3 weeks after the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.

More for Colorado

Cucumbers in other states

Frost dates for every city in Colorado