Arizona Hardiness Zones

Flowers in Phoenix
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If you live in Arizona and decide to plant a garden or establish landscaping around your house, then it might help to know your area's plant hardiness zones. There are two standard zone maps used throughout the United States, one created by the United States Department of Agriculture (USDA) and another by Sunset Magazine, a popular lifestyle publication. Due to Arizona's vast and varied geography ranging from mountains to desert valleys, the state experiences multiple climates that affect hardiness zones.

Arizona USDA Hardiness Zone Map

The USDA plant hardiness zone map is the standard across the country by which gardeners and growers can determine what plants can survive at a given location. The map presents the average annual minimum winter temperature, divided into 10-degree zones. You can use the interactive USDA zone map to input your zip code to see which plant hardiness zone applies to you.

The USDA map divides Arizona into 13 zones ranging from 5a to 10b. With an elevation of 6,909 feet, Flagstaff is located in zone 6a and is the state's highest major municipality and experiences cold winters where temperatures can drop to negative 10 degrees Fahrenheit. While Yuma, Arizona's hottest city, resides in zone 10a and has very mild winters where lows do not dip below 35 degrees Fahrenheit. Sedona experiences slightly colder winters in zone 8a with lows dipping to 10 to 15 degrees Fahrenheit.

Landscaping in Phoenix, Arizona
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Sunset vs. USDA Hardiness Zones

Sunset zones are based on total climate and other variables, including the length of growing season, rainfall, temperature lows and highs, wind, humidity, elevation, and microclimates. While the USDA hardiness map tells you where a plant may survive the winter, Sunset zone maps help you determine where a plant may thrive year-round.

You may find that specialty garden shops and nurseries prefer to use the Sunset zones instead of the USDA hardiness zones since the criteria are more thorough. However, seed packages commonly use USDA zones, so it can be helpful to know both types of zones for your particular area.

Arizona Sunset Hardiness Zones

The Sunset guide separates the state into eight zones: 1A, 2A, 2B, 3A, 10, 11, 12, and 13. Zones 1A, 2A, 2B, and 3A define mountain and intermountain climates. Zones 10–13 represent high, medium, intermediate, and low desert areas.

Phoenix is located in zone 13 as it's considered a lower desert based on its 1,086-foot elevation above sea level. At 3,586 feet, Benson resides in zone 10 where the city experiences colder winters with up to 100 nights that dip below freezing. The town of Winslow lies in the mild mountain climate of zone 3A and boasts some of Arizona's best weather for gardening with a long growing season lasting up to 186 days.

Gardening in Arizona

Since much of Arizona is dry and arid, researching desert-friendly plants for your yard is an excellent place to start. However, you'll still need to confirm whether a plant will survive in your specific climate zone. After your trees, vegetables, shrubs, and flowers are planted and thriving, you can refer to a monthly desert garden checklist for recommended garden activities and maintenance.