The U.S. Department of Agriculture (USDA) has released an updated version of its Plant Hardiness Zone Map (PHZM), a crucial tool for gardeners and researchers, marking the first update since 2012. Developed in collaboration with Oregon State University’s PRISM Climate Group, the 2023 map is more accurate and detailed than previous versions. The map, available online, is based on 30-year averages of the lowest annual winter temperatures, divided into 10-degree Fahrenheit zones with 5-degree Fahrenheit half-zones. The update incorporates data from 13,412 weather stations, compared to 7,983 in 2012, offering new features and improved resolution for Alaska. The map, crucial for approximately 80 million American gardeners and growers, also influences crop insurance standards and scientific research models. The shift in half zones indicates a warming trend. The 2023 map is available for free download and printing, emphasizing its accessibility to the public.

Full news release from the USDA Agricultural Resource Service