USDA Plant Hardiness Zones · 2023 map

What growing zone is Wyoming?

Wyoming’s ZIP codes span USDA plant hardiness zones 4a to 5b. The most common zone, covering 114 of 190 ZIP codes, is 5a (−20 to −15°F average coldest winter night).

USDA hardiness zones in Wyoming

ZoneAvg. extreme minimumZIP codesExample cities
Zone 4a−30 to −25°F9Laramie
Zone 4b−25 to −20°F41Gillette, Jackson
Zone 5a−20 to −15°F114Casper, Rock Springs, Sheridan, Evanston
Zone 5b−15 to −10°F26Cheyenne
 ZIP codes from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). Unpopulated areas such as high mountains can be colder than any ZIP code.

Growing zone and frost dates by city

CityZoneFrost dates
Cheyenne5b (−15 to −10°F)Cheyenne frost dates
Casper5a (−20 to −15°F)Casper frost dates
Gillette4b (−25 to −20°F)Gillette frost dates
Laramie4a (−30 to −25°F)Laramie frost dates
Rock Springs5a (−20 to −15°F)Rock Springs frost dates
Sheridan5a (−20 to −15°F)Sheridan frost dates
Evanston5a (−20 to −15°F)Evanston frost dates
Green River5a (−20 to −15°F)Green River frost dates
Riverton5a (−20 to −15°F)Riverton frost dates
Jackson4b (−25 to −20°F)Jackson frost dates
Cody5a (−20 to −15°F)Cody frost dates
Rawlins5a (−20 to −15°F)Rawlins frost dates
Lander5a (−20 to −15°F)Lander frost dates
Powell5a (−20 to −15°F)Powell frost dates
Douglas5a (−20 to −15°F)Douglas frost dates
Torrington5a (−20 to −15°F)Torrington frost dates
 Incorporated cities with 5,000+ residents. Each city uses the zone of its central ZIP code.

Frequently asked questions

What growing zone is Wyoming in?

Wyoming’s ZIP codes span USDA zones 4a to 5b, and 5a 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 Wyoming frost dates page.