Why USDA Zones Matter
Zones are based on the average annual extreme minimum temperature over a 30 year period. They predict cold tolerance but not heat stress, soil, rainfall, or pests. Use them as a guide rather than a guarantee.
Interactive USDA Zone Finder Tool by RadGarden.com
USDA Hardiness Zones by State and Major City
| State | Zones (examples by major city) |
|---|---|
| Alabama | 7b (Birmingham), 8a (Montgomery), 8b (Mobile) |
| Alaska | 1a (Utqiaġvik/Barrow), 2b (Fairbanks), 4a (Anchorage), 6a (Kodiak) |
| Arizona | 4b (Flagstaff), 8b (Phoenix), 9b (Tucson), 10a (Yuma) |
| Arkansas | 6b (Fayetteville), 7b (Little Rock), 8a (Texarkana) |
| California | 5a (Truckee), 9b (Los Angeles), 10a (San Diego), 10b (Palm Springs) |
| Colorado | 3a (Leadville), 5b (Denver), 6a (Colorado Springs), 6b (Pueblo) |
| Connecticut | 5b (Hartford), 6a (New Haven), 6b (Bridgeport) |
| Delaware | 7a (Dover), 7b (Wilmington) |
| Florida | 8b (Tallahassee), 9b (Orlando), 10b (Miami), 11a (Key West) |
| Georgia | 7a (Atlanta), 8a (Augusta), 8b (Savannah) |
| Hawaii | 10a (Hilo), 11a (Honolulu), 11b (Kona/Maui lowlands) |
| Idaho | 3b (Idaho Falls), 4b (Boise), 6a (Lewiston) |
| Illinois | 5a (Rockford), 5b (Chicago), 6b (Carbondale) |
| Indiana | 5b (South Bend), 6a (Indianapolis), 6b (Evansville) |
| Iowa | 4b (Sioux City), 5a (Des Moines), 5b (Iowa City) |
| Kansas | 5b (Kansas City), 6a (Wichita), 6b (Dodge City) |
| Kentucky | 6a (Lexington), 6b (Louisville), 7a (Bowling Green) |
| Louisiana | 8a (Shreveport), 8b (Baton Rouge), 9a (New Orleans) |
| Maine | 3b (Caribou), 4b (Bangor), 5a (Portland) |
| Maryland | 6a (Hagerstown), 7a (Baltimore), 7b (Annapolis) |
| Massachusetts | 5a (Worcester), 6a (Boston), 6b (Martha’s Vineyard) |
| Michigan | 4b (Traverse City), 5b (Detroit), 6a (Ann Arbor) |
| Minnesota | 3a (Duluth), 4a (Minneapolis), 4b (Rochester) |
| Mississippi | 7b (Tupelo), 8a (Jackson), 8b (Biloxi) |
| Missouri | 5b (St. Joseph), 6a (Kansas City), 6b (St. Louis) |
| Montana | 3a (Glasgow), 4a (Billings), 5a (Missoula) |
| Nebraska | 4a (North Platte), 5a (Omaha), 5b (Lincoln) |
| Nevada | 5a (Elko), 7a (Reno), 8b (Las Vegas) |
| New Hampshire | 4a (Berlin), 5a (Concord), 5b (Manchester) |
| New Jersey | 6a (Morristown), 6b (Newark), 7a (Atlantic City) |
| New Mexico | 4b (Taos), 6b (Albuquerque), 8a (Las Cruces) |
| New York | 3b (Saranac Lake), 5a (Albany), 7b (New York City) |
| North Carolina | 6a (Boone), 7b (Charlotte), 8a (Wilmington) |
| North Dakota | 3a (Fargo), 3b (Bismarck), 4a (Grand Forks) |
| Ohio | 5b (Cleveland), 6a (Columbus), 6b (Cincinnati) |
| Oklahoma | 6a (Guymon), 7a (Oklahoma City), 7b (Tulsa) |
| Oregon | 5b (Bend), 7a (Eugene), 8b (Portland) |
| Pennsylvania | 5b (Erie), 6b (Harrisburg), 7a (Philadelphia) |
| Rhode Island | 6a (Providence), 6b (Newport) |
| South Carolina | 7a (Greenville), 8a (Columbia), 8b (Charleston) |
| South Dakota | 3b (Rapid City), 4b (Sioux Falls), 5a (Vermillion) |
| Tennessee | 6a (Knoxville), 6b (Nashville), 7b (Memphis) |
| Texas | 6b (Amarillo), 8a (Dallas), 9a (Houston), 9b (Brownsville) |
| Utah | 4a (Logan), 5b (Salt Lake City), 7a (St. George) |
| Vermont | 3b (Newport), 4b (Burlington), 5a (Rutland) |
| Virginia | 5b (Roanoke), 7a (Richmond), 7b (Norfolk) |
| Washington | 4b (Spokane), 6b (Yakima), 8b (Seattle) |
| West Virginia | 5b (Morgantown), 6a (Charleston), 6b (Huntington) |
| Wisconsin | 3b (Superior), 4b (Madison), 5a (Milwaukee) |
| Wyoming | 3a (Sheridan), 4b (Cheyenne), 5a (Laramie) |
Note: Based on the 2023 USDA map. Microclimates can shift you by ~½ zone. For precise results, use a point lookup on a map or your garden records.
How to Read the USDA Zones Map
Each color represents a zone and sub zone. Zone 1 is coldest, zone 13 is warmest. “a” is the cooler half, “b” is the warmer half. Data comes from 1991–2020 averages. Remember that rare cold snaps can still damage plants even if they are “hardy” to your zone.
2023 Update to USDA Plant Hardiness Zones
The USDA released an updated map in November 2023. Many places shifted a half zone warmer, about 0–5 °F. The new map uses more weather stations and includes a “Tips for Growers” section.
Heat Matters Too, AHS Heat Zones
The USDA map covers cold. The American Horticultural Society heat zone map covers heat stress, ranking areas by the number of days above 86 °F. Together they give a more complete picture of plant survival.
Microclimates in Your Yard
Your yard may be warmer or cooler than the map suggests. Valleys trap cold, south walls store heat, water moderates temperature, and trees provide shade. Use microclimates to place borderline plants in protected spots.
How to Use USDA Zones Without Getting Burned
Know your USDA hardiness zone and your heat zone. Adjust for microclimates. Choose plants with a safety margin. Protect new plantings during severe cold. Keep soil healthy and moist to reduce stress.
FAQs
What’s the difference between USDA zones and heat zones?
USDA zones track average annual extreme minimums. Heat zones track days above 86 °F.
Why did my zone change in 2023?
The update used new data and stations, shifting many areas warmer.
Are USDA zones proof of climate change?
Not directly. Zone shifts can result from updated methods as well as warming trends.
Do USDA zones apply outside the U.S.?
No, other countries use different systems.
How do I garden on a zone boundary?
Use microclimates. Place tender plants in protected areas and pick hardier types for exposed spots.
Find Your Zone and Start Planting
Check your USDA zones map with your ZIP code, note your heat zone, and walk your yard for microclimates. Combine all three for the smartest planting choices.