Clematis Culture and Care Vines and Shrubs-Adding Elevation and Structure to the Garden Clematis are climbing or creeping plants that produce stunning blue, purple, pink, rose, yellow or white flowers. Sun: 6 hours a day. Best planting time: spring, after the risk of frost has passed. Some may bloom all summer and into the fall, while others are early spring bloomers. Certain cultivars can grow up to 20 feet (6.1 m) In general, clematis prefers full sun, but there are a few varieties that manage in part shade. Clematis (pronounced clem-atis) is within the buttercup family, Ranunculaceae, with about 300 species and many more hybrids with an array of different shapes, colors, characteristics, and flowering varieties. The old gardeners’ adage goes that clematis “love their feet in the shade and their faces in the sun.” While there’s some truth to that sweeping statement, what clematis actually love most of all is moist soil—which may or may not be present if the plant is forced to … Formerly categorized as Clematis paniculata, sweet autumn clematis can grow to 30 feet, though 15 feet is a more typical mature size.It has a fast growth rate, gaining a few feet in length each year. Clematis Care Must-Knows Clematis is an easy-to-grow perennial vine as long as you keep a few things in mind. 1 About Clematis. ; Most are hardy to USDA zones 4 to 9. This twining vine has leathery, shiny, dark green leaves. Size: varies from 2 to 30 meters in length.