Colorado Planting Calendar

Frost dates, growing zones, and planting dates for Colorado gardeners.

Zone 3a Zone 3b Zone 4a Zone 4b Zone 5a Zone 5b Zone 6a Zone 6b Zone 7a

The Short Answer

Colorado spans USDA zones 3a through 7a, which means planting dates vary significantly across the state. Front Range (Denver) has an average last frost around May 1 - May 15, while Mountain Regions sees its last frost around Jun 1 - Jun 20. Use our homepage tool with your zip code for dates specific to your exact location.

Colorado Frost Dates by Region

High altitude means intense sun but cool nights. Low humidity. Hail risk in late spring. Short but intense growing season at elevation.

Region	Zones	Last Frost (Spring)	First Frost (Fall)
Front Range (Denver)	5a, 5b, 6a	May 1 - May 15	Sep 25 - Oct 10
Western Slope	4b, 5a, 5b, 6a	May 10 - Jun 1	Sep 15 - Oct 5
Mountain Regions	3a, 3b, 4a, 4b	Jun 1 - Jun 20	Aug 25 - Sep 15

Soil & Growing Conditions

Alkaline clay soils common along Front Range. Rocky, thin soils in mountains. Amend heavily with compost and sulfur to lower pH.

What to Plant in Colorado

Colorado's short growing season rewards strategic planning. Cold-hardy crops are your strength, and warm-season crops need indoor starting. These are the best performers for Colorado's climate:

Top Picks for Colorado

Kale Garlic Potatoes Peas Carrots Lettuce Broccoli Beets Radishes Spinach Beans (Green/Snap)Cabbage Daffodils

Worth the Effort

With indoor starting and season extension, Colorado gardeners also grow excellent tomatoes, peppers, cucumbers, and sunflowers. The long summer daylight hours drive faster growth than you'd expect:

Tomatoes Peppers Cucumbers Squash (Summer)Basil Sunflowers Zinnias Corn (Sweet)

Browse all 100 plants — or enter your zip code for personalized planting dates.

Neighboring States

Gardeners near state borders may find useful information in neighboring state guides:

Alabama Alaska Arizona Arkansas California Connecticut Delaware Florida Georgia Hawaii Idaho Illinois Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Massachusetts Michigan Minnesota Mississippi Missouri Montana Nebraska Nevada New Hampshire New Jersey New Mexico New York North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania Rhode Island South Carolina South Dakota Tennessee Texas Utah Vermont Virginia Washington West Virginia Wisconsin Wyoming

Note: Frost dates are based on NOAA 30-year Climate Normals and represent historical averages. Actual frost dates can vary significantly year to year. Zone data is from the USDA Plant Hardiness Zone Map.

Last reviewed: March 29, 2026