Annuals must be planted every year. Though they occasionally drop seeds and surprise you with a reappearance, annuals almost always complete their life cycle in one growing season. Once annual flowers begin blooming, they tend to bloom until frost, providing almost constant color. Perennials, on the other hand, have a specific period of bloom. They can help you create a garden that will change throughout the growing season.
Most perennial plants die back to the ground each winter, but the roots remain alive underground.
When spring comes, the plants emerge from the soil, sending up new shoots from old roots. Thus, it is important to plan for third-year leaping when you first plant your garden, and you will also have to plan to have patience. Perennial flowers will not provide you with a carpet of continual color in the same way that a mass planting of annual impatiens or petunias will. They will offer a deep and abiding connection to the changing seasons, creating a personal calendar by which to mark your days. You can, of course, plant both annual and perennial flowers together.