Monday, February 20, 2012

USDA releases new Plant Hardiness Zone Map

The U.S. Department of Agriculture recently released a new color coded Plant Hardiness Zone Map for the United States.

Plant Hardiness Zone Map

The USDA has collaborated with Oregon State University to produce an updated Plant Hardiness Zone Map -- the first since 1990. According to the USDA's website, the new map features much greater detail than the old version, in part because the map was created using digital or Geographic Information System (GIS) based data combined with a "sophisticated algorithm".

The USDA's upgraded website is more user friendly and well worth a visit. Improvements include:
  • Interactive map with zoom and customized terrain adjustment
  • Downloadable Plant Hardiness Zone Maps available in several different sizes and resolutions.
  • Hardiness zones searchable by zip code, state, and region.
  • GIS data downloads (license necessary)

The latest map shows a slight warming trend compared to the 1990 edition. The USDA reports that the new map is generally a half a zone warmer than the earlier version. The USDA has also defined two new hotter zones that didn't exist on the previous map -- zones 12 and 13.

Read more about the new map on the USDA's Plant Hardiness Zone Map website.


jgoodland said...

Have the frost-free dates changed?

David said...

The Plant Hardiness Zone Map graphically represents the average winter lows over the given period, which is not directly related to frost dates. This data is somewhat harder to find, but the one of the better tools we know of is at​guides/freeze-frost-dates/.