The USDA Plant Hardiness Zone Map illustrates the lowest temperatures that can be expected in the United States. These temperatures are represented as average minimum temperatures based on the lowest temperatures recorded from the years 1974 to 1986. While selecting plant material for your next project, it is paramount that you refer to the Zone rating given for each plant and follow the requirements given. When referring to the U.S.D.A. Plant Hardiness Zone Map and the zone recommendations in this catalog, you will find that a large majority of our material is suitable for planting across the United States.