What is the purpose of the USDA plant hardiness zone map?

The USDA plant hardiness zone map is primarily intended to guide growers on plant survival in various climates. It categorizes regions based on their average annual minimum winter temperatures, which helps determine which plants can survive and thrive in specific areas. Each zone on the map represents a range of temperatures that are crucial for understanding how plants will fare in different geographical locations.

For example, if a grower knows their location falls within a particular hardiness zone, they can select plants that are well-suited to that climate, ensuring better growth and survival rates. This information is vital for gardeners and commercial growers alike, allowing them to make informed decisions about plant selection based on local temperature conditions. The other options provided do not align with the primary function of the hardiness zone map, as it does not address soil types, pest prevalence, or irrigation needs directly. It specifically focuses on temperature tolerance and plant vitality in relation to climate.