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.

For the first time, the map is available as an interactive GIS-based map. 
Users may also simply type in a ZIP Code and find the hardiness zone for that area.

via planthardiness.ars.usda.gov