If you want a perennial purple-flowering vine, look no further than the many purple cultivars of clematis (Ranunculaceae). These vines bloom from late winter until late fall with masses of flowers. Hardiness and a profusion of flowers make clematis a popular choice for landscapers and home gardeners living in the colder regions of the United States. Among the hundreds of species of clematis only a few of the evergreens are not cold-hardy.
The majority of clematis vines produce single flowers that range in size from 1 to 10 inches. A few varieties produce both double and single flowers and other clematis produce only double. When grown in full sun, some flowers change color during the life cycle. If grown in shade, the pastels hold their color. The seed heads of the spent flowers can be used in flower arrangements. Many of the flowers produce a scent, with C. armandii being the most highly scented. To bloom profusely, clematis need a dormant period of about six weeks. It takes about a week of 45 degrees F weather for them to go dormant.
Purple Species and Cultivars
Among the many purple clematis are:
C. alpina Helsingborg, deep purple bell-shaped flowers of 1 to 2 inches, blooms in April and May, grows 6 to 8 feet tall, zones 3 to 9.
Dorothy Walton species, 70-year-old French variety, 5-inch pointed flowers, blooms midsummer through fall, grows to 8 feet tall, zones 4 to 9.
Elsa Spath, rich violet-purple flowers of 6 to 8 inches, blooms May, June, September, grows 8 to 10 feet tall, zones 3 to 9.
Haku Ookan, rich-violet purple flowers of 6 to 7 inches, flowers are double in May and June, and single in September, grows 8 to 12 feet tall, zones 3 to 9.
C. alpina Tage Lundell, dark rosy purple flowers of 1 1/2 to 2 inches, blooms in April and May, grows to 10 feet tall, zones 3 to 9.
Planting and Care
Plant clematis in well-draining soil amended with compost (organic matter). Plant the crown that meets the roots at 2 inches below the surface of the soil. Mulch the roots to keep them moist and cool. However, take care not to overwater the plant. Provide a trellis or some other support for the clematis to climb.
Some clematis bloom on the previous season's growth, and other varieties bloom on new growth. You need to know the variety of clematis before pruning it. Skip pruning if you don't know the variety and its pruning needs. The large-flowering varieties that bloom in the spring on old growth get pruned lightly in late winter or early spring. Prune from the top down and remove only dead and damaged stems. The smaller-flowered clematis that flower on new growth need extensive pruning in early spring. Start from the bottom and work up and remove all top growth. After the early bloomers are spent, deadhead them to encourage another flowering.
USDA Hardiness Zones and Clematis
The cold-hardiness zones of clematis range from zone 3 to zone 9. These zones lie in the Northeast region of the United States. If you live in the following states, clematis thrive in your cold temperatures: Connecticut, Delaware, District of Columbia,Illinois, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, New Hampshire,New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, Virginia, West Virginia