There are 11 planting zones in the United States. Plant zones are defined by a 10 degree Fahrenheit difference in the avaerage annual minimum temperature. Seed dealers usually label plants so we know in what planting zone the plant will grow best. Growing plants that are not recommended for your plant zone might not be successful but it is possible. An experienced gardeners usually grow plants that are not recommended for their plant zone. There is a USDA map that shows the planting zones which was first intorduced in 1960, but recently the map was updated. USDA stands for United States Department of Agriculture. Plant zones are also known as USDA plant zones, USDA hardiness zones, USDA growing zones and USDA plant growing zones. When planting it is extremely recommended to look for plant zones so you get a succesfull plant. Finding your plant zone is not hard. Usually all plants have a label that reads for what plant zone it is. Some of cold hardy plants include Peoniesm, Ninebark, Goldenrod and Oriental Poppy. Plants that are not cold hardy include Bird of Paradise, Purple Fountain Grass, Gerbera Daisy and Elephant Ear. Most of the United States lies in planting zones 4 to 8.