USDA Hardiness Zones
These Zones are based on the average annual extreme minimum temperature expressed in degrees Fahrenheit (°F) ) or Celsius (°C). The main factors determining average annual extreme minimum temperature are elevation, latitude and proximity to the coast. Extreme minimum winter temperatures are a major determinant of whether a particular plant selection can be successfully grown outside year around. However, the USDA Hardiness Zones do not take into account other aspects influencing plant survival and performance, such as snow cover, summer heat, humidity, soil moisture, spring frosts, etc.
Other maps:
- See below for Oregon, Washington and Idaho
- For other states see https://planthardiness.ars.usda.gov/
From the USDA-OSU, released 2023 See https://planthardiness.ars.usda.gov/pages/map-downloads)
