Perennials are plants that faithfully come back year after year. They typically bloom after a period of dormancy during the winter months. They are relatively easy to grow and offer an abundance of blooms in a vast array of colors and forms. Ornamental grasses are also grouped in the perennial plant family.
Perennial plants live more than two years. They are the most versatile group of plants. There is a flowering perennial for every growing condition—from shade to full sun and from dry, sandy soil to soil that is rich and moist.
The majority of perennials die back with the onset of cold weather. The root system remains alive through the winter and sends forth new foliage and flowers each spring and summer.
Most perennials have a short blooming period. Different flowers, however, bloom for different lengths of time and at different seasons. Azaleas (in the Rhododendron genus) bloom for 2 to 3 weeks in early spring while the Christmas rose (Helleborus niger) blooms for about 8 weeks in late winter.
Perennials naturally grow denser every year. Dividing the plants every few years is necessary for size control, rejuvenation, and propagation.
The leaves of perennials outlive their blooms, providing the garden with a continuity of foliage. Daylilies (Hemerocallis) and Japanese irises (Iris kaempferi) are among the perennials most prized for the effect of their foliage.
Some hardy perennials, such as peony and bleeding heart, have been known to outlive their owners.