What is a plant hardiness zone?
USDA hardiness zones are 13 geographic areas based on average annual minimum winter temperatures. They help gardeners know which plants will survive in their climate.
What do the zone letters (a, b) mean?
Each zone is divided into "a" (colder half) and "b" (warmer half), representing 5°F temperature increments. Zone 7a is colder than 7b.
Is this only for the US?
Currently we support US zip codes. The USDA hardiness zone system is primarily used in the United States.
How accurate is the zone data?
We use the official USDA Plant Hardiness Zone Map data, updated to reflect current climate averages.
Can I look up by city name?
Currently lookup is by zip code. You can use our Zip Codes API to convert city names to zip codes.
Does the zone tell me when to plant?
Zones indicate what will survive winter, not when to plant. Combine with frost date data for planting schedules.
