USDA plant hardiness zones
The 2023 USDA map splits the U.S. into 13 zones, 10°F apart, each split into a and b half-zones 5°F apart, based on the average coldest winter night from 1991–2020.
| Zone | °F | °C | Cities on this site |
|---|---|---|---|
| 1a | -60 to -55°F | -51.1 to -48.3°C | 0 |
| 1b | -55 to -50°F | -48.3 to -45.6°C | 0 |
| 2a | -50 to -45°F | -45.6 to -42.8°C | 1 |
| 2b | -45 to -40°F | -42.8 to -40.0°C | 0 |
| 3a | -40 to -35°F | -40.0 to -37.2°C | 0 |
| 3b | -35 to -30°F | -37.2 to -34.4°C | 0 |
| 4a | -30 to -25°F | -34.4 to -31.7°C | 2 |
| 4b | -25 to -20°F | -31.7 to -28.9°C | 3 |
| 5a | -20 to -15°F | -28.9 to -26.1°C | 14 |
| 5b | -15 to -10°F | -26.1 to -23.3°C | 21 |
| 6a | -10 to -5°F | -23.3 to -20.6°C | 44 |
| 6b | -5 to 0°F | -20.6 to -17.8°C | 46 |
| 7a | 0 to 5°F | -17.8 to -15.0°C | 42 |
| 7b | 5 to 10°F | -15.0 to -12.2°C | 35 |
| 8a | 10 to 15°F | -12.2 to -9.4°C | 33 |
| 8b | 15 to 20°F | -9.4 to -6.7°C | 59 |
| 9a | 20 to 25°F | -6.7 to -3.9°C | 35 |
| 9b | 25 to 30°F | -3.9 to -1.1°C | 63 |
| 10a | 30 to 35°F | -1.1 to 1.7°C | 63 |
| 10b | 35 to 40°F | 1.7 to 4.4°C | 36 |
| 11a | 40 to 45°F | 4.4 to 7.2°C | 14 |
| 11b | 45 to 50°F | 7.2 to 10.0°C | 0 |
| 12a | 50 to 55°F | 10.0 to 12.8°C | 0 |
| 12b | 55 to 60°F | 12.8 to 15.6°C | 1 |
| 13a | 60 to 65°F | 15.6 to 18.3°C | 0 |
| 13b | 65 to 70°F | 18.3 to 21.1°C | 0 |