Assuming you provide the right amount of light, water and nutrients for your plants, the one remaining intangible in ensuring plant growth is temperature, especially cold temperatures. The United States Department of Agriculture (USDA) has developed a standardized Hardiness Zone Map to assist you in identifying the average annual minimum temperature for your area. Once you know your Hardiness Zone, you can then pick those plants that are best adapted to survive through the Winter.

The following pages describe the methodology used to develop Hardiness Zone Maps, recent proposals to change the USDA Hardiness Zone Map and alternative approaches to determining the optimum growing climate for a plant. There are few authoritative references on the Internet that provide a complete discussion of Hardiness Zone Maps, so the following is an attempt to consolidate the sources.

1. What is a Hardiness Zone?
2. What is my Hardiness Zone?
3. The 1990 USDA Hardiness Zone Map and Its Predecessors
4. Proposed Changes to the 1990 USDA Map -
• American Horticultural Society (AHS) draft changes
• Other Approaches
5. Evolution of hardiness zone maps for Florida
6. What does the future, especially the threat of global warming, hold in store?