In addition to the USDA Zone Map below, you may find a climate zone map published by Sunset Magazine helpful. It contains detailed climate information on dozens of well-defined regions throughout the continental U.S. To view the map, click here.
Annual seed can generally be planted in any garden in any area of the world. The maturity of the plant will depend on the length of the growing season in specific areas. If you know how long your growing season is you can choose plants that have enough time to mature by looking at "Days to Maturity" listed on each seedpack and in each seed description, for example (60-90 days).
Successful perennial gardening requires an understanding of the hardiness zone in your specific microclimate. An easy way to find your zone is by knowing what your minimum temperature is during the wintertime. Once you know your zone you'll know if your perennial plant will be able to over-winter in your garden without dying.
The USDA provides a Hardiness Zone Map
, as well as a chart to find the Average Minimum Temperature
in your area. Please remember that this is a general zone chart and does not necessarily take into account the specific microclimate where you have your garden. Coldframes, south-facing slopes, heavy winter mulches, etc. can allow plants to survive in a colder zone than is indicated.