When to plant watermelon in Colorado

Watermelon
Plant out in Denver
May 18–Jun 1

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–Jun 1
Sow outdoors, Denver
May 18–Jun 1
Last sowing for a harvest
Jun 16
Last frost, Denver
May 4

Start seeds indoors 3–4 weeks before the last frost; plant out 2–4 weeks after the last frost; sow outdoors 2–4 weeks after the last frost. In short-season areas, start seedlings indoors and pick an early variety.

Watermelon planting dates by city

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost
JanFebMarAprMayJunJulAugSepOctNovDec
DenverMay 18–Jun 1
Colorado SpringsMay 17–May 31
AuroraMay 21–Jun 4
Fort CollinsMay 16–May 30
LakewoodMay 17–May 31
ThorntonMay 16–May 30
ArvadaMay 19–Jun 2
WestminsterMay 16–May 30
GreeleyMay 16–May 30
PuebloMay 14–May 28
CentennialMay 19–Jun 2
BoulderMay 20–Jun 3
LongmontMay 21–Jun 4
LovelandMay 24–Jun 7
BroomfieldMay 16–May 30
Commerce CityMay 17–May 31
Grand JunctionApr 28–May 12
LittletonMay 16–May 30
BrightonMay 17–May 31
WindsorMay 17–May 31
ErieMay 21–Jun 4
NorthglennMay 16–May 30
Security-WidefieldMay 17–May 31
EnglewoodMay 16–May 30
Pueblo WestMay 10–May 24
Wheat RidgeMay 19–Jun 2
LafayetteMay 16–May 30
FountainMay 17–May 31
EvansMay 16–May 30
JohnstownMay 24–Jun 7
All 34 cities
CityStart indoorsPlant outSow outdoorsLast frost
DenverApr 6 to Apr 13May 18 to Jun 1May 18 to Jun 1May 4
Colorado SpringsApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
AuroraApr 9 to Apr 16May 21 to Jun 4May 21 to Jun 4May 7
Fort CollinsApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
LakewoodApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
ThorntonApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
ArvadaApr 7 to Apr 14May 19 to Jun 2May 19 to Jun 2May 5
WestminsterApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
GreeleyApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
PuebloApr 2 to Apr 9May 14 to May 28May 14 to May 28Apr 30
CentennialApr 7 to Apr 14May 19 to Jun 2May 19 to Jun 2May 5
BoulderApr 8 to Apr 15May 20 to Jun 3May 20 to Jun 3May 6
LongmontApr 9 to Apr 16May 21 to Jun 4May 21 to Jun 4May 7
LovelandApr 12 to Apr 19May 24 to Jun 7May 24 to Jun 7May 10
BroomfieldApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
Commerce CityApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
Grand JunctionMar 17 to Mar 24Apr 28 to May 12Apr 28 to May 12Apr 14
LittletonApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
BrightonApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
WindsorApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
ErieApr 9 to Apr 16May 21 to Jun 4May 21 to Jun 4May 7
NorthglennApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
Security-WidefieldApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
EnglewoodApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
Pueblo WestMar 29 to Apr 5May 10 to May 24May 10 to May 24Apr 26
Wheat RidgeApr 7 to Apr 14May 19 to Jun 2May 19 to Jun 2May 5
LafayetteApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
FountainApr 5 to Apr 12May 17 to May 31May 17 to May 31May 3
EvansApr 4 to Apr 11May 16 to May 30May 16 to May 30May 2
JohnstownApr 12 to Apr 19May 24 to Jun 7May 24 to Jun 7May 10
Four Square MileApr 9 to Apr 16May 21 to Jun 4May 21 to Jun 4May 7
MontroseMar 31 to Apr 7May 12 to May 26May 12 to May 26Apr 28
LouisvilleApr 8 to Apr 15May 20 to Jun 3May 20 to Jun 3May 6
FirestoneApr 9 to Apr 16May 21 to Jun 4May 21 to Jun 4May 7

Questions

When should I plant watermelon in Colorado?

In Denver, plant out from May 18 to June 1. 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 2–4 weeks after the last frost; sow outdoors 2–4 weeks after the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.

More for Colorado

Watermelon in other states

Frost dates for every city in Colorado