What Hardiness Zone Is Colorado?
Colorado spans USDA hardiness zones 4a–7a on the 2023 Plant Hardiness Zone Map. The most common zone is 6a, covering 44% of Colorado's ZIP codes, followed by zone 5b (35%). Zone 6a means the coldest night of an average winter reaches −10°F to −5°F (−23°C to −21°C). Enter your ZIP code for your exact zone.
Colorado hardiness zones by share of ZIP codes
What the zones mean for Colorado gardeners
- Coldest and warmest towns: among towns with NOAA weather stations, Antero Rsvr (8,939 ft) is in zone 4a, while Palisade (4,751 ft) is in zone 7a. That is a difference of about 30°F in the coldest night of a typical winter.
- Same zone, different frost dates: within zone 6a, the median last spring frost ranges from April 24 at John Martin Dam to June 11 at Ridgway, 48 days apart. Your zone tells you which perennials survive winter; your frost dates tell you when to plant.
Typical frost dates in each Colorado zone
Medians across NOAA weather stations in each zone. Colder zones usually have later spring frosts, but local terrain can shift the dates by weeks.
| Zone | Last spring frost | First fall frost | Stations |
|---|---|---|---|
| 5a | June 6 | September 17 | 15 |
| 5b | May 16 | October 1 | 60 |
| 6a | May 4 | October 8 | 46 |
| 6b | May 3 | October 9 | 11 |
| 7a | April 27 | October 16 | 8 |
Hardiness zones for Colorado cities
Zones at the National Weather Service stations, mostly city airports, with their median frost dates.
| Aspen Pitkin County Airport | 5b | −15°F to −10°F | 7,720 | May 31 | Sep 23 |
| Boulder 14 W | 5b | −15°F to −10°F | 9,828 | Jun 21 | Sep 2 |
| Colorado Springs Municipal Airport | 6a | −10°F to −5°F | 6,181 | May 3 | Oct 8 |
| Cortez 8 SE | 7a | 0°F to 5°F | 8,034 | May 6 | Oct 14 |
| Cortez Montezuma County Airport | 7a | 0°F to 5°F | 5,914 | May 27 | Sep 28 |
| Denver Centennial Airport | 6a | −10°F to −5°F | 5,883 | May 5 | Oct 8 |
| Denver Intl Airport | 6a | −10°F to −5°F | 5,414 | May 5 | Oct 9 |
| Denver-stapleton | 6a | −10°F to −5°F | 5,286 | May 4 | Oct 8 |
| Dinosaur 2 E | 6a | −10°F to −5°F | 6,062 | May 2 | Oct 14 |
| Durango La Plata County Airport | 6b | −5°F to 0°F | 6,660 | Jun 1 | Sep 27 |
| Grand Junction Walker Field | 7a | 0°F to 5°F | 4,858 | Apr 28 | Oct 16 |
| Lamar Municipal Airport | 6a | −10°F to −5°F | 3,704 | May 2 | Oct 7 |
| Leadville Lake County Airport | 5a | −20°F to −15°F | 9,932 | Any month | Any month |
| Limon Wsmo | 5b | −15°F to −10°F | 5,364 | May 21 | Sep 26 |
| Meeker Airport | 5b | −15°F to −10°F | 6,390 | May 30 | Sep 22 |
| Montrose 11 ENE | 6b | −5°F to 0°F | 8,402 | May 20 | Oct 1 |
| Nunn 7 NNE | 5a | −20°F to −15°F | 5,390 | May 13 | Sep 27 |
| Rifle Garfield County Airport | 6a | −10°F to −5°F | 5,530 | May 11 | Oct 4 |
| Trinidad Perry Stokes Airport | 6a | −10°F to −5°F | 5,741 | May 4 | Oct 9 |
Hardiness zones for 158 towns in Colorado
Each NOAA weather station is shown with the USDA zone of the nearest ZIP code (within 8 miles). Coldest night is the zone's range for the average annual extreme minimum temperature. Click a column to sort.
| Akron 4 E | 5b | −15°F to −10°F | 4,542 | May 8 | Oct 6 |
| Alamosa 1E | 4b | −25°F to −20°F | 7,540 | May 30 | Sep 17 |
| Allenspark 3NW | 5b | −15°F to −10°F | 8,500 | Jun 14 | Sep 12 |
| Antero Rsvr | 4a | −30°F to −25°F | 8,939 | Any month | Any month |
| Aspen Pitkin County Airport | 5b | −15°F to −10°F | 7,720 | May 31 | Sep 23 |
| Bailey | 5b | −15°F to −10°F | 7,752 | Jun 16 | Sep 8 |
| Black Canyon Of The Gunnison | 6a | −10°F to −5°F | 8,151 | May 23 | Oct 1 |
| Black Forest 6WNW | 5b | −15°F to −10°F | 6,957 | May 11 | Oct 6 |
| Blanca 4 NW | 5a | −20°F to −15°F | 7,709 | May 25 | Sep 22 |
| Bonham Rsvr | 5b | −15°F to −10°F | 9,852 | Any month | Any month |
| Boulder | 6a | −10°F to −5°F | 5,484 | May 6 | Oct 5 |
| Boulder 14 W | 5b | −15°F to −10°F | 9,828 | Jun 21 | Sep 2 |
| Briggsdale | 5a | −20°F to −15°F | 4,862 | May 12 | Sep 28 |
| Brighton 3 SE | 5b | −15°F to −10°F | 5,016 | May 3 | Oct 7 |
| Buckhorn Mountain 1 E | 5b | −15°F to −10°F | 7,400 | May 21 | Sep 29 |
| Burlington | 6a | −10°F to −5°F | 4,162 | May 6 | Oct 9 |
| Byers 5 ENE | 5b | −15°F to −10°F | 5,101 | May 13 | Oct 2 |
| Cabin Creek | 5a | −20°F to −15°F | 10,020 | Jun 6 | Sep 19 |
| Campo 7 S | 6b | −5°F to 0°F | 4,105 | Apr 29 | Oct 13 |
| Canon City | 6a | −10°F to −5°F | 5,378 | May 4 | Oct 7 |
| Castle Rock | 5b | −15°F to −10°F | 6,185 | May 9 | Oct 2 |
| Cedaredge 3E | 5b | −15°F to −10°F | 6,838 | May 3 | Oct 9 |
| Cheesman | 5b | −15°F to −10°F | 6,880 | May 17 | Oct 1 |
| Cheraw 1 N | 6a | −10°F to −5°F | 4,147 | Apr 30 | Oct 10 |
| Cherry Creek Dam | 6a | −10°F to −5°F | 5,647 | May 7 | Oct 8 |
| Cheyenne Wells 2NE | 6a | −10°F to −5°F | 4,203 | May 1 | Oct 14 |
| Climax | 5a | −20°F to −15°F | 11,344 | Any month | Any month |
| Coal Creek Canyon | 5b | −15°F to −10°F | 8,950 | Jun 5 | Sep 16 |
| Colorado National Monument | 7a | 0°F to 5°F | 5,781 | Apr 26 | Oct 16 |
| Colorado Springs Municipal Airport | 6a | −10°F to −5°F | 6,181 | May 3 | Oct 8 |
| Cortez 8 SE | 7a | 0°F to 5°F | 8,034 | May 6 | Oct 14 |
| Cortez Montezuma County Airport | 7a | 0°F to 5°F | 5,914 | May 27 | Sep 28 |
| Crested Butte | 5a | −20°F to −15°F | 8,867 | Any month | Any month |
| Crestone 2 SE | 5a | −20°F to −15°F | 8,004 | May 26 | Sep 26 |
| Cripple Creek 3NNW | 5b | −15°F to −10°F | 9,235 | May 26 | Sep 26 |
| Crook | 5b | −15°F to −10°F | 3,709 | May 11 | Oct 4 |
| Cumbre Vista - Colorado Springs 1 | 5b | −15°F to −10°F | 6,942 | May 9 | Oct 6 |
| Del Norte 3ENE | 5b | −15°F to −10°F | 7,845 | May 23 | Sep 25 |
| Delta 3E | 6b | −5°F to 0°F | 5,027 | May 1 | Oct 7 |
| Denver Centennial Airport | 6a | −10°F to −5°F | 5,883 | May 5 | Oct 8 |
| Denver Intl Airport | 6a | −10°F to −5°F | 5,414 | May 5 | Oct 9 |
| Denver Water Dept | 6a | −10°F to −5°F | 5,228 | Apr 30 | Oct 12 |
| Denver-stapleton | 6a | −10°F to −5°F | 5,286 | May 4 | Oct 8 |
| Dillon 1 E | 5a | −20°F to −15°F | 9,065 | Any month | Any month |
| Dinosaur 2 E | 6a | −10°F to −5°F | 6,062 | May 2 | Oct 14 |
| Divide 4NW | 5b | −15°F to −10°F | 9,134 | Jun 1 | Sep 21 |
| Durango La Plata County Airport | 6b | −5°F to 0°F | 6,660 | Jun 1 | Sep 27 |
| Eads | 6a | −10°F to −5°F | 4,212 | Apr 30 | Oct 13 |
| Eastonville 2 NNW | 5b | −15°F to −10°F | 7,210 | May 29 | Sep 21 |
| Elizabeth 2NW | 5b | −15°F to −10°F | 6,611 | May 16 | Oct 2 |
| Ellicott 7S | 6a | −10°F to −5°F | 5,739 | May 6 | Oct 3 |
| Estes Park 3 SSE | 5a | −20°F to −15°F | 7,812 | May 30 | Sep 17 |
| Evergreen | 5b | −15°F to −10°F | 6,985 | May 23 | Sep 22 |
| Fairplay S Park Rd | 5b | −15°F to −10°F | 9,995 | Jun 16 | Sep 9 |
| Flagler 1S | 5b | −15°F to −10°F | 4,921 | May 5 | Oct 8 |
| Fleming 3SW | 5b | −15°F to −10°F | 4,256 | May 4 | Oct 11 |
| Florissant Fossil Bed | 5a | −20°F to −15°F | 8,402 | Any month | Any month |
| Fort Collins | 5b | −15°F to −10°F | 5,004 | May 2 | Oct 7 |
| Fort Collins 4 E | 5b | −15°F to −10°F | 4,920 | May 3 | Oct 6 |
| Fort Lewis | 6a | −10°F to −5°F | 7,614 | Jun 1 | Sep 27 |
| Fraser | 5a | −20°F to −15°F | 8,560 | Any month | Any month |
| Gateway 1ENE | 6b | −5°F to 0°F | 4,671 | Apr 20 | Oct 21 |
| Georgetown | 5b | −15°F to −10°F | 8,520 | May 30 | Sep 19 |
| Glenwood Springs #2 | 6a | −10°F to −5°F | 5,895 | May 13 | Oct 3 |
| Grand Junction 6ESE | 7a | 0°F to 5°F | 4,760 | Apr 23 | Oct 20 |
| Grand Junction Walker Field | 7a | 0°F to 5°F | 4,858 | Apr 28 | Oct 16 |
| Grand Junction WFO | 7a | 0°F to 5°F | 4,826 | Apr 14 | Oct 23 |
| Grand Lake 1 NW | 5a | −20°F to −15°F | 8,720 | Any month | Any month |
| Grand Lake 6 SSW | 5a | −20°F to −15°F | 8,288 | Jun 13 | Sep 7 |
| Grant | 5b | −15°F to −10°F | 8,675 | Jun 15 | Sep 9 |
| Greeley Unc | 5b | −15°F to −10°F | 4,715 | May 2 | Oct 8 |
| Gross Rsvr | 6a | −10°F to −5°F | 7,970 | May 24 | Sep 23 |
| Hayden | 5a | −20°F to −15°F | 6,467 | Jun 1 | Sep 20 |
| Hermit 8 SE | 5a | −20°F to −15°F | 8,949 | Any month | Any month |
| Holly | 6a | −10°F to −5°F | 3,401 | May 1 | Oct 12 |
| Holyoke | 5b | −15°F to −10°F | 3,780 | May 11 | Oct 3 |
| Hourglass Rsvr | 5b | −15°F to −10°F | 9,520 | Any month | Any month |
| Idalia | 6a | −10°F to −5°F | 3,965 | May 4 | Oct 9 |
| Ignacio 6ESE | 6a | −10°F to −5°F | 6,548 | May 23 | Sep 29 |
| Joes | 5b | −15°F to −10°F | 4,275 | May 3 | Oct 9 |
| John Martin Dam | 6a | −10°F to −5°F | 3,814 | Apr 24 | Oct 15 |
| Julesburg | 5b | −15°F to −10°F | 3,477 | May 7 | Oct 6 |
| Kassler | 5b | −15°F to −10°F | 5,587 | May 8 | Oct 3 |
| Kit Carson | 5b | −15°F to −10°F | 4,302 | May 10 | Oct 1 |
| Kremmling | 5a | −20°F to −15°F | 7,460 | Jun 14 | Sep 5 |
| La Junta | 6a | −10°F to −5°F | 4,089 | Apr 26 | Oct 15 |
| La Junta 20 S | 6a | −10°F to −5°F | 4,210 | Apr 27 | Oct 14 |
| Lake City | 5a | −20°F to −15°F | 8,667 | Jun 8 | Sep 17 |
| Lakewood | 6a | −10°F to −5°F | 5,640 | May 3 | Oct 7 |
| Lamar Municipal Airport | 6a | −10°F to −5°F | 3,704 | May 2 | Oct 7 |
| Leadville Lake County Airport | 5a | −20°F to −15°F | 9,932 | Any month | Any month |
| Limon Wsmo | 5b | −15°F to −10°F | 5,364 | May 21 | Sep 26 |
| Lindon 5 WNW | 5b | −15°F to −10°F | 4,851 | May 15 | Oct 2 |
| Longmont 2 ESE | 5b | −15°F to −10°F | 4,950 | May 7 | Oct 5 |
| Manassa | 5a | −20°F to −15°F | 7,695 | May 28 | Sep 21 |
| Mancos 1SW | 6a | −10°F to −5°F | 6,897 | Jun 4 | Sep 24 |
| Marston Fltr Plt | 6a | −10°F to −5°F | 5,610 | May 2 | Oct 11 |
| Matheson 8 SE | 5b | −15°F to −10°F | 5,830 | May 12 | Oct 2 |
| Meeker Airport | 5b | −15°F to −10°F | 6,390 | May 30 | Sep 22 |
| Meredith | 6a | −10°F to −5°F | 7,825 | Any month | Any month |
| Mesa Verde National Park | 7a | 0°F to 5°F | 7,142 | May 9 | Oct 14 |
| Monte Vista 2W | 5a | −20°F to −15°F | 7,695 | Jun 11 | Sep 13 |
| Montrose 11 ENE | 6b | −5°F to 0°F | 8,402 | May 20 | Oct 1 |
| Monument | 5b | −15°F to −10°F | 7,080 | May 14 | Oct 1 |
| Monument 3S | 5b | −15°F to −10°F | 6,821 | May 17 | Oct 1 |
| Northglenn | 6a | −10°F to −5°F | 5,407 | May 2 | Oct 11 |
| Nunn 7 NNE | 5a | −20°F to −15°F | 5,390 | May 13 | Sep 27 |
| Ordway 21 N | 5b | −15°F to −10°F | 4,767 | May 3 | Oct 7 |
| Ouray | 5b | −15°F to −10°F | 7,840 | May 17 | Oct 1 |
| Palisade | 7a | 0°F to 5°F | 4,751 | Apr 17 | Oct 26 |
| Paonia 1SW | 6b | −5°F to 0°F | 5,581 | May 3 | Oct 12 |
| Paradox 2N | 6b | −5°F to 0°F | 5,447 | May 11 | Oct 5 |
| Parker | 5b | −15°F to −10°F | 5,904 | May 9 | Oct 3 |
| Placerville | 5b | −15°F to −10°F | 7,383 | May 26 | Sep 29 |
| Pueblo Rsvr | 6a | −10°F to −5°F | 4,861 | Apr 26 | Oct 13 |
| Ralston Rsvr | 6a | −10°F to −5°F | 5,900 | May 3 | Oct 14 |
| Ridgway | 6a | −10°F to −5°F | 7,049 | Jun 11 | Sep 13 |
| Rifle Garfield County Airport | 6a | −10°F to −5°F | 5,530 | May 11 | Oct 4 |
| Rocky Ford 2 SE | 6a | −10°F to −5°F | 4,170 | May 1 | Oct 8 |
| Roxborough State Park | 5b | −15°F to −10°F | 6,117 | May 16 | Oct 1 |
| Ruxton Park | 5b | −15°F to −10°F | 9,060 | Jun 3 | Sep 17 |
| Rye 1SW | 6a | −10°F to −5°F | 7,141 | May 5 | Oct 10 |
| Salida | 5b | −15°F to −10°F | 7,160 | May 29 | Sep 20 |
| San Luis 1 S | 5b | −15°F to −10°F | 7,943 | May 31 | Sep 23 |
| Sargents | 5b | −15°F to −10°F | 8,460 | Any month | Any month |
| Sedgwick 5 S | 5b | −15°F to −10°F | 3,996 | May 6 | Oct 7 |
| Seibert | 5b | −15°F to −10°F | 4,706 | May 4 | Oct 11 |
| Sheep Mountain | 6a | −10°F to −5°F | 7,744 | May 27 | Sep 25 |
| Sheridan Lake | 6a | −10°F to −5°F | 4,070 | Apr 27 | Oct 15 |
| Silverton | 5a | −20°F to −15°F | 9,285 | Any month | Any month |
| Spicer | 4b | −25°F to −20°F | 8,385 | Any month | Any month |
| Steamboat Springs | 5b | −15°F to −10°F | 6,866 | Jun 9 | Sep 12 |
| Sterling | 5b | −15°F to −10°F | 3,974 | Apr 30 | Oct 9 |
| Stratton | 6a | −10°F to −5°F | 4,399 | May 6 | Oct 9 |
| Strontia Springs Dam | 5b | −15°F to −10°F | 5,840 | May 16 | Sep 29 |
| Tacony 13 SE | 6a | −10°F to −5°F | 4,882 | May 5 | Oct 6 |
| Taylor Park | 5a | −20°F to −15°F | 9,179 | Jun 20 | Sep 8 |
| Telluride 4WNW | 5b | −15°F to −10°F | 8,646 | Any month | Any month |
| Trinidad | 6a | −10°F to −5°F | 6,030 | Apr 30 | Oct 15 |
| Trinidad Perry Stokes Airport | 6a | −10°F to −5°F | 5,741 | May 4 | Oct 9 |
| Twin Lakes Rsvr | 5a | −20°F to −15°F | 9,236 | Jun 16 | Sep 10 |
| Uravan | 6b | −5°F to 0°F | 5,021 | Apr 26 | Oct 18 |
| Vail | 5b | −15°F to −10°F | 8,304 | Jun 21 | Sep 7 |
| Vallecito Dam | 6a | −10°F to −5°F | 7,644 | May 31 | Sep 26 |
| Virginia Dale 7 ENE | 5b | −15°F to −10°F | 7,015 | May 31 | Sep 19 |
| Walden | 4b | −25°F to −20°F | 8,056 | Any month | Any month |
| Walsenburg 1 NW | 6a | −10°F to −5°F | 6,292 | May 6 | Oct 4 |
| Walsh 1 W | 6b | −5°F to 0°F | 3,978 | Apr 30 | Oct 14 |
| Waterdale | 5b | −15°F to −10°F | 5,230 | May 12 | Oct 1 |
| Westcliffe | 5b | −15°F to −10°F | 7,873 | Jun 11 | Sep 9 |
| WFO Pueblo | 6a | −10°F to −5°F | 4,653 | Apr 30 | Oct 9 |
| Wheat Ridge 2 | 6a | −10°F to −5°F | 5,398 | May 5 | Oct 5 |
| Wild Horse 6N | 6a | −10°F to −5°F | 4,654 | May 4 | Oct 8 |
| Wray | 5b | −15°F to −10°F | 3,553 | May 7 | Oct 6 |
| Yampa | 5a | −20°F to −15°F | 7,857 | Jun 14 | Sep 11 |
| Yellow Jacket 2W | 6b | −5°F to 0°F | 6,933 | May 17 | Oct 9 |
| Yellow Jacket 4NE | 6b | −5°F to 0°F | 7,090 | May 15 | Oct 8 |
| Yuma | 5b | −15°F to −10°F | 4,134 | May 1 | Oct 12 |
Frequently asked questions
What hardiness zone is Colorado?
Colorado is in USDA hardiness zones 4a–7a on the 2023 USDA Plant Hardiness Zone Map. Zone 6a is the most common, covering 44% of Colorado's ZIP codes, and zone 5b covers 35%. Enter your ZIP code for your exact zone.
What does zone 6a mean?
Zone 6a means the average annual extreme minimum temperature, the coldest night of a typical winter, is −10°F to −5°F (−23°C to −21°C). Perennials, shrubs and trees rated for zone 6a or colder should survive winter there.
What is the coldest hardiness zone in Colorado?
Zone 4a is the coldest zone mapped in Colorado, found around Antero Rsvr, and zone 7a is the warmest, found around Palisade.
Did Colorado's hardiness zones change in 2023?
The USDA released a new Plant Hardiness Zone Map in November 2023, based on 1991–2020 temperatures instead of 1976–2005. About half of the United States shifted half a zone warmer. Check your ZIP code here, because plant tags and older books may still list your 2012 zone.
When should I plant in zone 6a?
Hardiness zones don't set planting dates; frost dates do. Inside zone 6a in Colorado, the median last spring frost varies from April 24 to June 11. Look up your local frost dates and plant tender crops such as tomatoes after the 10%-risk last-frost date.
Zone and frost dates: use both
Your hardiness zone answers one question: will this plant survive the winter here? Choose perennials, shrubs, trees and bulbs rated for your zone or a colder one. For vegetables and annuals, what matters is the length of the frost-free season. See Colorado frost dates by town, or get a planting calendar for your ZIP code with start-indoors, transplant and sowing dates for 30 crops.
Sources and method
Zones are from the USDA 2023 Plant Hardiness Zone Map ZIP-code files published by the PRISM Climate Group, Oregon State University, based on 1991–2020 minimum temperatures. ZIP codes are assigned to states by USPS prefix. Town zones use the ZIP code nearest each NOAA 1991–2020 Climate Normals station. This is an independent tool, not an official USDA site. Full methodology.
Hardiness zones in other states
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Connecticut
- Delaware
- District of Columbia
- 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
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- Puerto Rico