locations.ġ21 (50%) of the 242 locations experienced an increase in their plant hardiness zone (e.g., from Zone 5 to Zone 6) at some point over the period of analysis. This analysis averaged each location’s annual minimum temperatures over a rolling 30-year period, from 1951-1980 to the present (1993-2022), and found:Īverage annual minimum temperatures warmed in 231 (95%) of 242 locations.Ĭompared to a 1951-1980 baseline, the average annual minimum temperatures during the most recent 30-year period (1993-2022) were 3.1☏ warmer on average across all 242 U.S. ![]() Summary statistics below are based on 242 locations (see Methodology). Kudzu, a fast-growing invasive vine projected to continue to expand from the Southeast into the Mid-Atlantic, Midwest, and Northeast.īrown marmorated stink bug, an urban nuisance pest and agricultural pest in at least 15 states, whose geographic range is projected to grow partly due to warmer, wetter winters.Ĭoldest annual temperatures warming locallyĬlimate Central also assessed the long-term change in the coldest temperatures of the year-which determines which plants are likely to thrive-in 247 U.S. While this can have benefits (e.g., expanding the range of high-value crops), it can also expand the range of harmful and/or invasive plant and insect species such as: ![]() Maps for the three most recent normal periods show plant hardiness zones shifting to the north as the coldest time of year warms.Īs minimum temperatures warm and a location's planting zone increases (e.g., from Zone 5 to Zone 6), certain plants and insects may expand into areas where they previously wouldn't have survived the coldest winter temperatures. Planting zones are based on annual minimum normal temperatures, and winter warmed the most between the 20 normal periods. Click the downloadable graphic: Shifting Planting Zones Map Planting zones shifting north across the U.S.Īs our climate warms due to heat-trapping carbon pollution, planting zones have shifted north toward higher latitudes and elevations. In addition to annual minimum temperature, other factors such as growing degree days, local rainfall, and soil type also affect which plants can thrive in a given area. The USDA also uses plant hardiness zones to set some crop insurance standards. (except in high mountains and along coasts).Ī location's annual minimum temperatures (on which planting zones are based) affect which plants and insects can survive over winter-and therefore partly determine the geographic range of wild, cultivated, and invasive species. Maps from USDA and NOAA show bands of similar planting zones running roughly east to west across the U.S. Plants adapted to mild winters and hot summers, such as watermelons and tangerines, thrive in Zone 8 (10 to 20☏), which runs through the Southeast and central Texas. For example:Ĭold-tolerant plants such as garlic and asparagus thrive in Zone 3 (-40 to -30☏), which runs across the upper Northeast, Midwest, and Plains. Each zone spans a 10☏ range in average annual minimum temperature. (including Alaska and Hawaii) is divided into 13 plant hardiness zones based on each location’s annual minimum temperature, averaged over 30-year normal periods. ![]() If heat-trapping carbon pollution continues these shifts could force growers to select plants adapted to a wider and warmer range of temperatures.Ĭlick the downloadable graphic: Local Shifting Planting Zones Plant hardiness zonesĪs gardeners and farmers across the country decide which plants to grow this spring, many look to plant hardiness zones for guidance. These 231 locations warmed by 3.3☏ on average since the 1951-1980 period. have shifted to the north over the three most recent 30-year normal periods.Īverage annual minimum temperatures warmed in 231 (95%) of 242 U.S. These zones-based on each location’s average annual minimum temperature-determine which plants can grow and thrive in different parts of the country.Īs the coldest times of year warm, plant hardiness zones across the contiguous U.S. Plant hardiness zones are shifting north as the U.S. ![]()
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