Colorado Planting Guide & Growing Season
Colorado is in USDA hardiness zone with a growing season of 150 days. The average last spring frost is Apr 15 - Jun 1 and the average first fall frost is Sep 15 - Oct 15. Climate data based on Denver.
Growing Conditions in Colorado
How Colorado Compares
Compare Colorado's growing conditions with states that have similar climates.
| State | USDA Zone | Last Frost | First Frost | Season (days) |
|---|---|---|---|---|
| Colorado (CO) | Apr 15 - Jun 1 | Sep 15 - Oct 15 | 150 | |
| Alabama (AL) | Mar 1 - Apr 1 | Oct 25 - Nov 15 | 220 | |
| Alaska (AK) | May 15 - Jun 15 | Aug 15 - Sep 15 | 105 | |
| Arizona (AZ) | Feb 1 - Apr 15 | Oct 15 - Dec 15 | 270 | |
| Arkansas (AR) | Mar 15 - Apr 15 | Oct 15 - Nov 1 | 210 | |
| California (CA) | Jan 15 - Apr 15 | Oct 15 - Dec 31 | 290 |
Frequently Asked Questions About Gardening in Colorado
When should I start seeds indoors in Colorado?
In Colorado, the average last frost date is Apr 15 - Jun 1. Start most seeds indoors 6-8 weeks before this date. The USDA hardiness zone for Colorado is undefined, with a growing season of approximately 150 days.
What USDA hardiness zone is Colorado?
Colorado falls in USDA hardiness zones undefined. This affects which perennial plants will survive winter and influences optimal planting times.
When is the first frost in Colorado?
The average first frost date in Colorado is Sep 15 - Oct 15. Plan to harvest cold-sensitive crops before this date or protect them with row covers.
How long is the growing season in Colorado?
Colorado has an average growing season of 150 days, from the last frost (Apr 15 - Jun 1) to first frost (Sep 15 - Oct 15). This shorter season requires starting many crops indoors and choosing quick-maturing varieties.
Plan Your Garden
Use our seed starting calculator to get personalized planting dates, or browse all states.