Important information for all gardeners and plant researchers.
Late fall, 2023, the U.S. Department of Agriculture released new plant hardiness zone maps. These maps are critical for all gardeners, beginners and professionals, on many acres or an apartment balcony, because they determine which perennial plants can be planted where and be counted on to thrive. The maps have been a valuable tool for gardeners and researchers and had not been updated since 2012. Much has happened in our climates in the past 12 years. These new maps are more accurate and have much greater detail than all previous versions.
The 2023 maps are based on 30-year averages of the lowest annual winter temperatures at specific locations. They are divided into 10-degree Fahrenheit zones and then divided into 5-degree Fahrenheit half-zones, designated as ‘A’ and ‘B’. When compared to the 2012 maps, it is apparent that about half the country has shifted to the next warmer half zone while the other half of the country remained where they were. The zones that shifted to the next warmer half zone means those areas warmed somewhere in the range of 0-5 degrees Farenheit. In particular, the states with the largest changes include Arkansas, Kentucky, Missouri, and Tennessee.
Changes in the updated maps:
This new version includes a “Tips for Growers” section which has information about research programs that might interest gardeners and those who grow and breed plants.
They incorporate data from 13,412 weather stations compared to the 7,983 used for the 2012 maps.
A paper version of the 2023 map will not be available for purchase, but anyone can download the new map for free and print as many copies as needed.
There is a personal zone finder map where you can enter your city and state and the first piece of information will be your zone in 2012, scroll down and the next information is your zone in the updated 2023 map. I put in two locations and both places had warmed and changed to the next warmer plant hardiness half zone.
Two new zones were added. Zones 12 and 13 are for regions with annual average minimum temperatures higher than 50 and 60 degrees Farenheit. These new zones apply only to Puerto Rico and Hawaii.
Click here to view the interactive map.
Click here for a pdf version of the map to download and print.
