Clematis

Clematis are perennials in the buttercup family (Ranunculaceae) some of which are climbers and others are spreading subshrubs or groundcovers. There are nearly 400 species and many more cultivars and hybrids. They are cosmopolitan in distribution. The genus name derives from the Greek word klēmatis, meaning broken branches, perhaps owing to its fragile stems. 

Depending upon the species and the support structure, they can grow to 1 to 18 feet long. They prefer full sun, with afternoon shade in areas with hot summers. Shade the roots with mulch or a ground cover planting. Moist, well-drained soil with a neutral to slightly alkaline pH is recommended. Clematis is deep-rooted, so water thoroughly. Clematis is a heavy feeder; provide it with a low nitrogen, slow-release fertilizer every 4 to 6 weeks throughout the growing season.

Pruning depends on whether they bloom on old wood or new wood. Growers recognize three pruning groups, generally called Type 1, Type 2 and Type 3.

• Type 1: These clematis set flower buds on old wood and bloom in early spring. These do not require regular pruning, but damaged stems should be removed any time immediately after flowering has finished. Example: C. montana.
• Type 2: These clematis bloom on old and new wood and flower in late spring. Light pruning (to shape or contain the vine) should be accomplished in late winter or early spring when the buds begin to swell. Examples: All large-flowered hybrids like C. × jackmanii and C. × hybrida. 
• Type 3: These are clematis that bloom on new wood and flower in summer or fall. This group includes the non-vining herbaceous perennial clematis. They can be cut nearly to the ground in late winter to encourage new stems from the crown. Examples: C. texensis and C. recta.

Stems are fragile and should be handled gently. The plants may be propagated by division, layering, or stem cutting. Large-flowered hybrids can have flowers up to 7 inches wide. Clematis flowers attract bees, butterflies, and hummingbirds; other birds may nest in the vines. The plants are deer- and rabbit-resistant. 

Use clematis in Asian, butterfly, cottage and pollinator gardens. They are also suitable for containers, naturalized areas, vertical spaces or woodlands. 

Insects, Diseases and Other Plant Problems: No significant problems. 

VIDEO Created by Elisabeth Meyer for "Annuals, Perennials, Vines, and Groundcovers" a plant identification course offered in partnership with Longwood Gardens.