NATIONWIDE — The U.S. Department of Agriculture (USDA) released a new version of its Plant Hardiness Zone Map (PHZM). The Upper Delaware region is generally in 6a, based on the lowest annual winter temperature of -10 degrees to -5 degrees Fahrenheit. 

The map allows gardeners and growers to determine which plants are most likely to thrive at a location. It is more accurate and contains greater detail than prior versions, a press release from the USDA stated.

The new map is based on 30-year averages of the lowest annual winter temperatures at specific locations, is divided into 10-degree Fahrenheit zones and further divided into five-degree Fahrenheit half-zones, and incorporates data from 13,412 weather stations, compared to the 7,983 that were used for the 2012 map.

The designations do not reflect the coldest it has ever been or ever will be at a specific location, but simply the average lowest winter temperature for the location over a specified time. Low temperature during the winter is a crucial factor in the survival of plants at specific locations.

The USDA Risk Management Agency refers to the map’s plant hardiness zone designations to set certain crop insurance standards. Additionally, scientists incorporate the zones as a data layer in many research models, such as those modeling the spread of exotic weeds and insects.

Although a paper version of the 2023 map will not be available for purchase from the government, anyone can download the new map free of charge and print copies as needed. The new map is available online at www.planthardiness.ars.usda.gov.