USDA Plant Hardiness Zone Map Posted on March 4, 2017March 4, 2017 by 101plants The 2012 USDA Plant Hardiness Zone Map is the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. The map is based on the average annual minimum winter temperature, divided into 10-degree F zones. Visit the USDA site for more info: http://planthardiness.ars.usda.gov/PHZMWeb/