FrostCal

When to Plant Watermelon in Colorado

In a typical Colorado location, start seeds indoors Apr 5 – Apr 12, then transplant outdoors May 17 – May 24. Across the state, the outdoor planting window starts as early as Apr 28 in Grand Junction and as late as Jul 5 in Edwards.

Method Start indoors, then transplant
Days to maturity 70–90 days

Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.

Watermelon Planting Dates by City

CityStart indoorsTransplant
DenverApr 2 – Apr 9May 14 – May 21
Colorado SpringsApr 5 – Apr 12May 17 – May 24
AuroraApr 6 – Apr 13May 18 – May 25
Fort CollinsApr 4 – Apr 11May 16 – May 23
LakewoodApr 5 – Apr 12May 17 – May 24
ThorntonApr 4 – Apr 11May 16 – May 23
WestminsterApr 4 – Apr 11May 16 – May 23
ArvadaApr 7 – Apr 14May 19 – May 26
CentennialApr 7 – Apr 14May 19 – May 26
PuebloApr 2 – Apr 9May 14 – May 21
GreeleyApr 4 – Apr 11May 16 – May 23
BoulderApr 8 – Apr 15May 20 – May 27
Highlands RanchApr 7 – Apr 14May 19 – May 26
LongmontApr 9 – Apr 16May 21 – May 28
LovelandApr 12 – Apr 19May 24 – May 31
BroomfieldApr 4 – Apr 11May 16 – May 23
Grand JunctionMar 17 – Mar 24Apr 28 – May 5
Castle RockApr 11 – Apr 18May 23 – May 30
Commerce CityApr 6 – Apr 13May 18 – May 25
ParkerApr 11 – Apr 18May 23 – May 30
LittletonApr 4 – Apr 11May 16 – May 23
NorthglennApr 4 – Apr 11May 16 – May 23
BrightonApr 5 – Apr 12May 17 – May 24
Dakota RidgeApr 4 – Apr 11May 16 – May 23
EnglewoodApr 4 – Apr 11May 16 – May 23
Security-WidefieldApr 5 – Apr 12May 17 – May 24
WindsorApr 5 – Apr 12May 17 – May 24
Ken CarylApr 4 – Apr 11May 16 – May 23
Wheat RidgeApr 7 – Apr 14May 19 – May 26
Pueblo WestMar 29 – Apr 5May 10 – May 17

Showing the 30 most populous of 65 Colorado cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Colorado cities.

Frequently Asked Questions

When should I plant watermelon in Colorado?

In a typical Colorado location, start seeds indoors Apr 5 – Apr 12, then transplant outdoors May 17 – May 24. Across the state, the outdoor planting window starts as early as Apr 28 in Grand Junction and as late as Jul 5 in Edwards.

When is the last frost in Colorado?

The average last spring frost in Colorado ranges from April 14 in Grand Junction to June 21 in Edwards, based on NOAA 1991–2020 climate normals.

How long do watermelon take to grow?

Watermelon typically take 70–90 days from planting to harvest. Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.

Other Crops in Colorado

When to plant watermelon in other states

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