US Hardiness Zones
What are the US Hardiness Zones? USDA's 2012 Hardiness Zone Map Hardiness zone maps were created to show where various permanent landscape plants can adapt. Perennials, shrubs, and trees must tolerate year-round weather conditions to survive and grow year-after-year. A hardiness zone is a geographically defined area in which a specific category of plant life is capable of growing, as determined by climatic conditions, including its ability to withstand the minimum temperatures of the zone. The current version of the USDA Hardiness Zone Map was jointly developed by USDA's Agricultural Research Service and Oregon State University's PRISM Climate Group. It was released in January 2012. The new map is generally one 5°F half-zone warmer than the 1990 plan throughout most of the United States. This change resulted from several factors including advances in technology, the inclusion of data from many more weather stations, and the use of temperature data from a longer a...