USDA plant hardiness zones
Your hardiness zone tells you which plants can live through winter where you are. Each zone is set by the average coldest night of the year. Zones step by 10°F. Each zone splits into a colder half (a) and a warmer half (b).
Find your zone
Zone temperatures
Each range is the average coldest night of the year.
| Zone | Coldest night (°F) | Coldest night (°C) | Plants |
|---|---|---|---|
| 1a | -60 to -55°F | -51.1 to -48.3°C | |
| 1b | -55 to -50°F | -48.3 to -45.6°C | |
| 2a | -50 to -45°F | -45.6 to -42.8°C | Zone 2 perennials |
| 2b | -45 to -40°F | -42.8 to -40°C | |
| 3a | -40 to -35°F | -40 to -37.2°C | Zone 3 perennials |
| 3b | -35 to -30°F | -37.2 to -34.4°C | |
| 4a | -30 to -25°F | -34.4 to -31.7°C | Zone 4 perennials |
| 4b | -25 to -20°F | -31.7 to -28.9°C | |
| 5a | -20 to -15°F | -28.9 to -26.1°C | Zone 5 perennials |
| 5b | -15 to -10°F | -26.1 to -23.3°C | |
| 6a | -10 to -5°F | -23.3 to -20.6°C | Zone 6 perennials |
| 6b | -5 to 0°F | -20.6 to -17.8°C | |
| 7a | 0 to 5°F | -17.8 to -15°C | Zone 7 perennials |
| 7b | 5 to 10°F | -15 to -12.2°C | |
| 8a | 10 to 15°F | -12.2 to -9.4°C | Zone 8 perennials |
| 8b | 15 to 20°F | -9.4 to -6.7°C | |
| 9a | 20 to 25°F | -6.7 to -3.9°C | Zone 9 perennials |
| 9b | 25 to 30°F | -3.9 to -1.1°C | |
| 10a | 30 to 35°F | -1.1 to 1.7°C | Zone 10 perennials |
| 10b | 35 to 40°F | 1.7 to 4.4°C | |
| 11a | 40 to 45°F | 4.4 to 7.2°C | Zone 11 perennials |
| 11b | 45 to 50°F | 7.2 to 10°C | |
| 12a | 50 to 55°F | 10 to 12.8°C | |
| 12b | 55 to 60°F | 12.8 to 15.6°C | |
| 13a | 60 to 65°F | 15.6 to 18.3°C | |
| 13b | 65 to 70°F | 18.3 to 21.1°C |
How zones work
USDA sets each zone from the average of the coldest night in each year from 1991 to 2020. A plant labeled zones 4 to 8 can survive winters in zone 4 and handle the heat of zone 8.
In the United States, we show the official zone from the 2023 USDA Plant Hardiness Zone Map. Everywhere else, including Canada, we estimate the USDA zone the same way, from 30 years of weather data. In our tests, the estimate landed within half a zone of the USDA map. Select-A-Plant uses USDA zones only.
Sources: USDA Plant Hardiness Zone Map (2023) through phzmapi.org. Weather data fromOpen-Meteo (ERA5, CC BY 4.0). Postal code locations fromOpenStreetMap contributors and zippopotam.us.