1. Home

Discuss in my forum

Planting Zones: USDA Plant Hardiness Zones

By

Photo of Angelina stonecrop. It's suited to planting zones 5 and warmer.

Some succulents, such as Angelina sedum (picture), are surprisingly cold-hardy.

David Beaulieu
Definition:

There are 11 planting zones on the USDA Plant Hardiness Map in the contiguous United States and southern Canada. The regions are defined by a 10 degree Fahrenheit difference in the average annual minimum temperature. To put the definition in layman's terms, the higher the numbers, the warmer the temperatures for gardening in those areas.

It is standard practice for seed dealers and nurseries to label their products according to their USDA Plant Hardiness Zones -- that is, the planting zones in which you'll be most successful at growing those particular plants.

Enthusiasts of horticulture plan their gardens carefully, and part of that planning means consulting maps showing the USDA planting zones. Growing plants not suited to your region's climate is sometimes possible, but not recommended for beginners. Those experienced in gardening and landscaping, however, often make use of what are known as "microclimates."

For a look at just where the various planting zones fall, consult the USDA maps I supply here, by region.

"USDA" stands for United States Department of Agriculture, the institution that published the original map showing USDA planting zones (1960). The publication was sponsored by the American Horticultural Society, in conjunction with the U.S. National Arboretum.

Examples of cold-hardy plants (numbers in parentheses indicate zones):

Examples of plants that are not very cold-hardy:

Also Known As: USDA plant zones, USDA hardiness zones, USDA growing zones, USDA plant growing zones
Examples:
Parts of northern Minnesota are considered to be in USDA planting zones 2 and 3; but central and southern Florida lie in USDA zones 9-11. The bulk of the U.S. lies in USDA planting zones 4-8.
  1. About.com
  2. Home
  3. Landscaping
  4. Help for Beginners
  5. Landscaping Dictionary
  6. Planting Zones - Definition of USDA Plant Hardiness Maps

©2014 About.com. All rights reserved.