USDA Zones

There are many factors that affect the hardiness of plants. Tolerance to cold, heat, wind, wetness and drought; soil conditions; plant size and age; light intensity; and day length all affect plant hardiness. While a plant may survive in one area, for a number of reasons it may not be as successful in another.

We have provided USDA hardiness ratings to help you in your selection of varieties. These ratings are for plants in the ground; keep in mind that perennials in pots may not be as hardy.
 

The USDA has released a map that encompasses 13 zones divided into finer increments and includes zone boundaries. Particularly useful (and fun!) is a website interface that allows you to look up zone information based on your zipcode and to view detailed state maps. Try it out at planthardiness.ars.usda.gov.