Agriculture Department maintains a map that breaks the nation into growing zones based on temperatures and average first and last frost dates.
Deciding what to grow — and when to plant it — starts with determining your hardiness zone. The U.S. Agriculture Department maintains a map that breaks the nation into growing zones based on temperatures and average first and last frost dates. Knowing your zone can keep you from planting too early, a common mistake that often results in plants getting zapped by a late frost. Even veteran gardeners should take a second look at the map: For the first time since 2012, the USDA made updates for this growing season that moved about half the country into a new zone.