By Mary H. Dyer, Master Naturalist and Master Gardener Are dahlia flowers annual or perennial? The flamboyant bloomers are classified as tender perennials, which means they may be annual or perennial, depending on your plant hardiness zone. Can dahlias be grown as perennials? The answer, again, depends on your climate. Read on to find out the real story. Can Dahlias Be Grown as Perennials? Perennials are plants that live for at least three years, while tender perennials won’t survive cold winters. Tender dahlia plants are actually tropical plants and they are perennial only if you live in USDA plant hardiness zone 8 or higher. If your hardiness zone is 7 or below, you have a choice: either grow dahlias as annuals or dig the tubers and store them until spring. Growing Dahlias Year Round In order to get the most of your dahlias, you’ll need to determine your hardiness zone.