FrostCal

When to Plant Zucchini in Colorado

In a typical Colorado location, start seeds indoors Apr 12 – Apr 19, then sow outdoors May 10 – May 24, then transplant outdoors May 10 – May 17. Across the state, the outdoor planting window starts as early as Apr 21 in Grand Junction and as late as Jun 28 in Edwards.

Method Direct sow
Days to maturity 45–55 days

Fast-growing squash; direct sow 1-3 weeks after last frost, or start indoors 2-3 weeks early for a head start.

Zucchini Planting Dates by City

CityStart indoorsDirect sowTransplant
DenverApr 9 – Apr 16May 7 – May 21May 7 – May 14
Colorado SpringsApr 12 – Apr 19May 10 – May 24May 10 – May 17
AuroraApr 13 – Apr 20May 11 – May 25May 11 – May 18
Fort CollinsApr 11 – Apr 18May 9 – May 23May 9 – May 16
LakewoodApr 12 – Apr 19May 10 – May 24May 10 – May 17
ThorntonApr 11 – Apr 18May 9 – May 23May 9 – May 16
WestminsterApr 11 – Apr 18May 9 – May 23May 9 – May 16
ArvadaApr 14 – Apr 21May 12 – May 26May 12 – May 19
CentennialApr 14 – Apr 21May 12 – May 26May 12 – May 19
PuebloApr 9 – Apr 16May 7 – May 21May 7 – May 14
GreeleyApr 11 – Apr 18May 9 – May 23May 9 – May 16
BoulderApr 15 – Apr 22May 13 – May 27May 13 – May 20
Highlands RanchApr 14 – Apr 21May 12 – May 26May 12 – May 19
LongmontApr 16 – Apr 23May 14 – May 28May 14 – May 21
LovelandApr 19 – Apr 26May 17 – May 31May 17 – May 24
BroomfieldApr 11 – Apr 18May 9 – May 23May 9 – May 16
Grand JunctionMar 24 – Mar 31Apr 21 – May 5Apr 21 – Apr 28
Castle RockApr 18 – Apr 25May 16 – May 30May 16 – May 23
Commerce CityApr 13 – Apr 20May 11 – May 25May 11 – May 18
ParkerApr 18 – Apr 25May 16 – May 30May 16 – May 23
LittletonApr 11 – Apr 18May 9 – May 23May 9 – May 16
NorthglennApr 11 – Apr 18May 9 – May 23May 9 – May 16
BrightonApr 12 – Apr 19May 10 – May 24May 10 – May 17
Dakota RidgeApr 11 – Apr 18May 9 – May 23May 9 – May 16
EnglewoodApr 11 – Apr 18May 9 – May 23May 9 – May 16
Security-WidefieldApr 12 – Apr 19May 10 – May 24May 10 – May 17
WindsorApr 12 – Apr 19May 10 – May 24May 10 – May 17
Ken CarylApr 11 – Apr 18May 9 – May 23May 9 – May 16
Wheat RidgeApr 14 – Apr 21May 12 – May 26May 12 – May 19
Pueblo WestApr 5 – Apr 12May 3 – May 17May 3 – May 10

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 zucchini in Colorado?

In a typical Colorado location, start seeds indoors Apr 12 – Apr 19, then sow outdoors May 10 – May 24, then transplant outdoors May 10 – May 17. Across the state, the outdoor planting window starts as early as Apr 21 in Grand Junction and as late as Jun 28 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 zucchini take to grow?

Zucchini typically take 45–55 days from planting to harvest. Fast-growing squash; direct sow 1-3 weeks after last frost, or start indoors 2-3 weeks early for a head start.

Other Crops in Colorado

When to plant zucchini in other states

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