|Is that Plant Hardy Enough for Your Garden?
USDA Plant Hardiness Zones
Perennial plants can live for several years, but only if they are cold hardy enough to handle the conditions in your garden. To help gardeners determine which plants are suitable for their area, the U.S. Department of Agriculture (USDA) mapped out 11 different zones the cover the United States, Canada and Mexico. Each zone represents a 10 degree F. difference in the annual minimum temperature. (Most are further divided into 5 degree F. differences denoted by a and b. For example, Zone 6a has a minimum temperature of -10 to -5 degrees F. Zone 6b has a minimum temperature of -5 to 0 degrees F.
Plants are tested and then labeled with their hardiness zone, taking some of the guesswork out of which plants are suitable for your garden. You'll see this color coded map used in books and magazines. It's easy enough to look up your area and check the key for your zone. But it's even easier to plug in your zip code (above)and and have your hardiness zone pop up. Go ahead and try it.