Your USDA hardiness zone is important to know if you are growing the kinds of plants that return every year like perennials, shrubs, hardy vines and grasses. If you don’t know your zone, click here and enter your zip code.
The hardiness zone map we use was created by the U.S. Department of Agriculture using climate records averaged over many decades. Hardiness zones are based on the average annual minimum temperatures for each zone. At Garden Crossings, we ship plants to people in zones 2-9, which covers the contiguous 48 states. The smaller the number your zone is, the colder your climate is. For example, parts of northern Minnesota are zone 3 but southern Florida is zone 9.
If a plant is listed as hardy in zones 5-8, that means it is expected to grow and survive the winter in those zones. It would not be expected to overwinter in zones 4 or colder. In zones warmer than 8, the plant would overwinter but would not likely tolerate the heat and may fail to thrive.
Annual plants, meaning those that people in most climates grow for one season and then dispose of, do have their hardiness zone listed on our website. You will notice their zones are very high, such as zone 10-11 for petunias. That means that petunias can survive the “winter” in zones 10-11, but they are grown as an annual in all zones cooler than zone 10.
Plants grown in the ground versus in containers are affected differently by the cold winter’s temperatures. Generally, plants overwintered in the ground are better insulated than those growing in containers. We cover this topic in depth in this article.