In 2023, the USDA updated its plant hardiness map after 11 years, impacting gardeners nationwide. The new map reflects changes in lowest winter temperatures, with some areas experiencing warmer weather. The map, based on 1991-2020 data, helps predict plants’ winter survival in specific zones. However, the map doesn’t account for extreme lowest temperatures, frequency of cold weather, or summer conditions. Different microclimates in cities with the same zone affect plant growth. To supplement the USDA map, the American Horticultural Society developed a heat zone map. Local nurseries and experts provide valuable information for successful gardening. For gardeners, understanding these factors is essential for planting and promoting a healthy garden.
https://apps.npr.org/plant-hardiness-garden-map/