USDA hardiness zones in Colorado
| Zone | Avg. extreme minimum | ZIP codes | Example cities |
|---|---|---|---|
| Zone 4a | −30 to −25°F | 1 | — |
| Zone 4b | −25 to −20°F | 8 | Alamosa |
| Zone 5a | −20 to −15°F | 65 | Eaton, Estes Park, Silverthorne, Breckenridge |
| Zone 5b | −15 to −10°F | 203 | Fort Collins, Greeley, Longmont, Castle Rock |
| Zone 6a | −10 to −5°F | 202 | Denver, Colorado Springs, Aurora, Lakewood |
| Zone 6b | −5 to 0°F | 28 | Montrose, Durango, Delta |
| Zone 7a | 0 to 5°F | 13 | Grand Junction, Fruita, Cortez |
Growing zone and frost dates by city
| City | Zone | Frost dates |
|---|---|---|
| Denver | 6a (−10 to −5°F) | Denver frost dates |
| Colorado Springs | 6a (−10 to −5°F) | Colorado Springs frost dates |
| Aurora | 6a (−10 to −5°F) | Aurora frost dates |
| Fort Collins | 5b (−15 to −10°F) | Fort Collins frost dates |
| Lakewood | 6a (−10 to −5°F) | Lakewood frost dates |
| Thornton | 6a (−10 to −5°F) | Thornton frost dates |
| Arvada | 6a (−10 to −5°F) | Arvada frost dates |
| Westminster | 6a (−10 to −5°F) | Westminster frost dates |
| Greeley | 5b (−15 to −10°F) | Greeley frost dates |
| Pueblo | 6a (−10 to −5°F) | Pueblo frost dates |
| Centennial | 6a (−10 to −5°F) | Centennial frost dates |
| Boulder | 6a (−10 to −5°F) | Boulder frost dates |
| Longmont | 5b (−15 to −10°F) | Longmont frost dates |
| Castle Rock | 5b (−15 to −10°F) | Castle Rock frost dates |
| Loveland | 5b (−15 to −10°F) | Loveland frost dates |
| Broomfield | 6a (−10 to −5°F) | Broomfield frost dates |
| Commerce City | 6a (−10 to −5°F) | Commerce City frost dates |
| Grand Junction | 7a (0 to 5°F) | Grand Junction frost dates |
| Parker | 5b (−15 to −10°F) | Parker frost dates |
| Littleton | 6a (−10 to −5°F) | Littleton frost dates |
| Brighton | 5b (−15 to −10°F) | Brighton frost dates |
| Windsor | 5b (−15 to −10°F) | Windsor frost dates |
| Erie | 5b (−15 to −10°F) | Erie frost dates |
| Northglenn | 6a (−10 to −5°F) | Northglenn frost dates |
| Englewood | 6a (−10 to −5°F) | Englewood frost dates |
| Wheat Ridge | 6a (−10 to −5°F) | Wheat Ridge frost dates |
| Lafayette | 6a (−10 to −5°F) | Lafayette frost dates |
| Fountain | 6a (−10 to −5°F) | Fountain frost dates |
| Evans | 5b (−15 to −10°F) | Evans frost dates |
| Johnstown | 5b (−15 to −10°F) | Johnstown frost dates |
| Montrose | 6b (−5 to 0°F) | Montrose frost dates |
| Louisville | 6a (−10 to −5°F) | Louisville frost dates |
| Golden | 5b (−15 to −10°F) | Golden frost dates |
| Firestone | 5b (−15 to −10°F) | Firestone frost dates |
| Durango | 6b (−5 to 0°F) | Durango frost dates |
| Frederick | 5b (−15 to −10°F) | Frederick frost dates |
| Cañon City | 6a (−10 to −5°F) | Cañon City frost dates |
| Castle Pines | 5b (−15 to −10°F) | Castle Pines frost dates |
| Greenwood Village | 6a (−10 to −5°F) | Greenwood Village frost dates |
| Lone Tree | 6a (−10 to −5°F) | Lone Tree frost dates |
| Berthoud | 5b (−15 to −10°F) | Berthoud frost dates |
| Federal Heights | 6a (−10 to −5°F) | Federal Heights frost dates |
| Fruita | 7a (0 to 5°F) | Fruita frost dates |
| Monument | 5b (−15 to −10°F) | Monument frost dates |
| Superior | 6a (−10 to −5°F) | Superior frost dates |
| Steamboat Springs | 5b (−15 to −10°F) | Steamboat Springs frost dates |
| Sterling | 5b (−15 to −10°F) | Sterling frost dates |
| Wellington | 5b (−15 to −10°F) | Wellington frost dates |
| Fort Morgan | 5b (−15 to −10°F) | Fort Morgan frost dates |
| Severance | 5b (−15 to −10°F) | Severance frost dates |
| Timnath | 5b (−15 to −10°F) | Timnath frost dates |
| Rifle | 6a (−10 to −5°F) | Rifle frost dates |
| Fort Lupton | 5b (−15 to −10°F) | Fort Lupton frost dates |
| Glenwood Springs | 6a (−10 to −5°F) | Glenwood Springs frost dates |
| Alamosa | 4b (−25 to −20°F) | Alamosa frost dates |
| Delta | 6b (−5 to 0°F) | Delta frost dates |
| Gypsum | 5b (−15 to −10°F) | Gypsum frost dates |
| Milliken | 5b (−15 to −10°F) | Milliken frost dates |
| Cortez | 7a (0 to 5°F) | Cortez frost dates |
| Craig | 5b (−15 to −10°F) | Craig frost dates |
| Lochbuie | 5b (−15 to −10°F) | Lochbuie frost dates |
| Trinidad | 6a (−10 to −5°F) | Trinidad frost dates |
| Woodland Park | 5b (−15 to −10°F) | Woodland Park frost dates |
| Lamar | 6a (−10 to −5°F) | Lamar frost dates |
| Eagle | 5b (−15 to −10°F) | Eagle frost dates |
| Mead | 5b (−15 to −10°F) | Mead frost dates |
| La Junta | 6a (−10 to −5°F) | La Junta frost dates |
| Dacono | 5b (−15 to −10°F) | Dacono frost dates |
| Gunnison | 5b (−15 to −10°F) | Gunnison frost dates |
| Carbondale | 6a (−10 to −5°F) | Carbondale frost dates |
| Aspen | 5b (−15 to −10°F) | Aspen frost dates |
| Cherry Hills Village | 6a (−10 to −5°F) | Cherry Hills Village frost dates |
| Avon | 6a (−10 to −5°F) | Avon frost dates |
| Salida | 6a (−10 to −5°F) | Salida frost dates |
| Sheridan | 6a (−10 to −5°F) | Sheridan frost dates |
| Eaton | 5a (−20 to −15°F) | Eaton frost dates |
| Estes Park | 5a (−20 to −15°F) | Estes Park frost dates |
| Silverthorne | 5a (−20 to −15°F) | Silverthorne frost dates |
| Brush | 5b (−15 to −10°F) | Brush frost dates |
| Breckenridge | 5a (−20 to −15°F) | Breckenridge frost dates |
Frequently asked questions
What growing zone is Colorado in?
Colorado’s ZIP codes span USDA zones 4a to 7a, and 5b is the most common. Zones vary with elevation and distance from water, so check your own ZIP code.
When should I plant?
Hardiness zones are about winter cold, not planting dates. For timing, use the last spring frost date for your city on our Colorado frost dates page.