U.S. planting zone charts are available from the USDA website and from companies that sell seeds and plants. The charts help gardeners and landscapers choose plants and planting dates.
The USDA chart is color-coded to separate the hardiness zones. Individuals can select state options or enter zip codes to get location-specific information. The government-produced USDA maps address the needed hardiness of plants for different regions.
Maps and charts provided by seed and nursery plant sellers provide the same hardiness data, as well as recommended planting times and the last day of frost for different regions. They also note when frost begins in the fall.