How does it help me choose varieties for my garden?
The USDA hardiness zone map divides the U.S. into zones based on the historical average lowest winter temperature. Perennials naturally live for more that one year, but not all of them can survive cold temperatures. For example, a plant that is perennial in Texas may not be perennial in Minnesota. Perennials are rated using the USDA zone system, indicating the coldest zone they can survive, allowing gardeners to choose hardy plants for their garden.
The hardiness zone does not relate to the average last frost date, just the average coldest temperature. Add your zipcode to the USDA site to find your hardiness zone.
Look to our online perennial descriptions for hardiness zones.