Right plant, right place: Discover your U.S. Plant Hardiness Zone

The United States Department of Agriculture (USDA) has divided the country into several planting zones, often referred to as "hardiness zones," to help gardeners and horticulturists determine which plants are most likely to thrive in a specific area.

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These zones are based on average minimum winter temperatures and are used to guide plant selection for optimal growth and survival. Use your plant hardiness zone to find plants most likely to survive your climate.

How are plant hardiness zones determined?

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The USDA Plant Hardiness Zone Map divides the United States into 11 main zones (ranging from 1 to 11) and further divides some zones into subzones (denoted by letters a and b). Each zone represents a 10°F difference in average annual minimum temperature. In 2023, the USDA updated the map to reflect the changing temperatures of the climate crisis.

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Here’s how the zones are determined by temperature:

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1. Zone 1: Minimum temperature below -50°F

2. Zone 2: Minimum temperature -50 to -40°F

3. Zone 3: Minimum temperature -40 to -30°F

4. Zone 4: Minimum temperature -30 to -20°F

5. Zone 5: Minimum temperature -20 to -10°F

6. Zone 6: Minimum temperature -10 to 0°F

7. Zone 7: Minimum temperature 0 to 10°F

8. Zone 8: Minimum temperature 10 to 20°F

9. Zone 9: Minimum temperature 20 to 30°F

10. Zone 10: Minimum temperature 30 to 40°F

11. Zone 11: Minimum temperature above 40°F

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Each of these zones is further divided into "a" and "b" subzones to account for smaller temperature gradients within the larger zones.

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It's important to note that while these planting zones provide valuable guidance, they are based solely on average winter temperatures and do not account for other factors that can impact plant growth, such as soil type, humidity, and summer temperatures. It's a good starting point for choosing plants, but local microclimates and specific conditions should also be considered when planning a garden or landscaping project.

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