When planning your garden, you must consider your zone. The hardiness of a plant indicates the ability of a plant to survive in a given climate. The Plant Hardiness Zone Map was created by the USDA to help growers identify the plants that tolerate the climates characteristic of their regions, or climatic "zones." The map divides the United States and southern Canada into eleven zones. Zone 1 has the coldest minimum temperatures, while Zone 11 has the warmest. So for example, if you live in Zone 4, you want to grow plants that are described as suitable or hardy to Zone 4, to ensure that they are tolerant to your climate. You would be taking a risk growing plants that are unsuited to your zone - in addition to climate incompatibility, you'd be putting your plants at much higher risk for disease.