Gardeners treasure perennial plants because they come back year after year. Annual plants, on the other hand, complete their growing cycle in one season and then die. Most gardeners structure their gardens around perennials and then add some annual plants. By growing perennials, gardeners usually spend less time weeding and planting. Choosing perennials to grow in the garden is a joy for many gardeners. They're available in a wide range of varieties, colors, sizes, forms and bloom times. When buying perennial plants, factors to consider are their grow zone, how much daily sunlight they need, what type of soil they grow best in, their mature height and spread, harvest or bloom time, flower color (if applicable) and other growing requirements.