The U.S. Department of Agriculture updated its Plant Hardiness Zone map for the first time in over a decade. The change factors in the warming climate.
The map is essentially a “what to plant where” guide put out by the USDA in collaboration with Oregon State University. It uses 30-year temperature averages and data collected from over 13,000 weather stations across the country.
The lower 48 states are 2.5 degrees warmer than they were in 2012, according to the USDA. Over half the country shifted to warmer plant zones on the new map.
Low winter temperatures are a key metric in determining plant survival at a given location. Data from the 5th National Climate Assessment shows Montana has increasing winter temperatures, and warm nights have become more common.
Northwestern Montana averages the warmest winter temps, while areas of the High Line remain the coldest.
USDA also published "Tips for Growers” online. Gardeners can learn more about what plants would be best suited to their area.
The map will be updated every 10 years.
