The climate classification system developed by the United States Department of Agriculture (USDA) divides North America into distinct geographic areas based on average annual minimum winter temperatures. These zones, numbered from 1 to 13, assist gardeners and growers in determining which plants are most likely to thrive in a specific location. Knowing this zone provides a baseline understanding of the cold hardiness required for plant survival. For instance, a plant labeled as hardy to zone 6 can generally withstand the average minimum winter temperature of that zone.
Understanding the appropriate zone is crucial for successful gardening and landscaping. It allows individuals to select plants that can endure the typical winter conditions, reducing the risk of plant loss due to freezing. This knowledge also informs decisions about protective measures that may be necessary for marginally hardy plants, such as mulching or providing temporary shelters. The USDA system has evolved over time, incorporating more sophisticated data and mapping techniques to provide increasingly accurate and localized information.