The United States Department of Agriculture (U.S.D.A.) has established Plant Hardiness Zones for the USA, Canada and Mexico based on analysis of the range of average annual minimum temperatures experienced in each area as recorded during the period 1974 through 1986. According to the U.S.D.A. temperature data book issued by Meteorological Evaluation Services Co. Inc. of Amityville, NY, "the purpose of this data listing is to enable one to determine the hardiness zone of any given city, town or location used in the map analysis as well as to provide the annual minimum temperatures over the 10-plus years for comparison with future weather."

When planning a garden, consider your local climate and the established "hardiness rating" of various plants you have in mind. Some plants cannot handle severe winters; others wither in heat; still others, such as many spring-flowering bulbs, need a cold period to stimulate growth cycles. Look at plant labels, bulb packaging, catalogues and reference books for the hardiness ratings of individual plants.

Plant spring-flowering bulbs in your area 6 weeks before the ground freezes.