Zones. Every zone on this site comes straight from the official 2023 USDA Plant Hardiness Zone Map ZIP code listings published by the PRISM Climate Group at Oregon State University, which produced the map with the USDA Agricultural Research Service. We use the data unaltered. This site is not the official USDA map; see planthardiness.ars.usda.gov for the official interactive map.
City and state names. ZIP code place names come from GeoNames postal code data, used under a Creative Commons Attribution 4.0 license (geonames.org). A city page lists every ZIP code GeoNames assigns to that city name, which can include PO box ZIP codes.
Background. Facts about the map come from the USDA Agricultural Research Service announcement of November 15, 2023.
Checked October 17, 2026.