Nashville has a new ‘plant hardiness zone’

Climate change is shifting what plants are ideal for Nashville. 

For the first time in a decade, the U.S. Department of Agriculture has updated its guidelines for what plants can thrive in certain areas in the country. The department released a new map last week of “plant hardiness zones,” which are based on the annual minimum temperature averaged over 30 years. 

USDA divides the nation into 13 hardiness zones, each separated by 10 degrees Fahrenheit, and every zone is split into five-degree subsets called a and b. 

Courtesy U.S. Department of Agriculture

Nashville is now classified as a “7b” plant hardiness zone.

“A plant hardiness zone is really just defined by the coldest night of the year,” John Abatzoglou, a climatology professor at the University of California, Merced, told WPLN earlier this year. 

Since 1950, Nashville’s average annual minimum temperature has changed from -0.3 to 9.2 degrees, the third-highest difference in the nation, according to Climate Central. 

Nashville moved from “7a” to “7b” in the latest map — so, think less red maples and more crepe myrtles and dwarf palmettos. Nashville could move into Zone 8 by 2040 based on projections by the National Oceanic and Atmospheric Administration.

There are other factors beyond minimum temperatures that affect plant hardiness, such as soil moisture, heat and humidity. The warming climate is affecting each of those factors, too.

USDA recommends consulting with local producers, nurseries or master gardeners for growing advice.