Clematis are lovely flowering vines that comprise many different species and cultivated varieties, each with their own growth forms and habits. Some clematis vines are evergreen, while others are deciduous and some are herbaceous perennials. Depending on the type, clematis vines can grow up to 30 feet tall or as small as 2- to 5-feet tall. Although most clematis enjoy the same basic care and environmental conditions, the timing and type of pruning can vary according to variety.
Provide a climbing support for your clematis vine. Clematis can climb on walls, around small trees or shrubs, or on trellises, fences or arbors. Ensure that the structure is large enough to accommodate the mature size of your clematis variety and that the climbing supports are thin like string or plastic-coated wire.
Water your clematis vine deeply once every week when rainfall is less than 1 inch. Provide water around the entire root system until the soil is evenly moistened.
Spread a 2-inch-thick layer of mulch on the ground around the clematis to cover its root system and keep the soil cool. Alternatively, you could plant groundcovers or perennials with shallow roots around the clematis to keep its roots shaded and cool. Each year in late spring, add more mulch to maintain a 2-inch depth.
Feed your clematis vine once every year in the spring with one-half-pound of 15-5-5 N-P-K fertiliser. Spread the fertiliser in a 50-square-foot area on the ground around the clematis. Alternatively, you can use a fertiliser with an N-P-K formula ratio of 4-1-2 or 3-1-2.
Know when to prune your clematis depending on the species or cultivated variety. Prune the early-flowering clematis types like Clematis alpina 'Constance' and Clematis montana 'Elizabeth' immediately after they've finished blooming. These types of clematis bloom on old wood. Prune large-blossomed, late-blooming clematis types like Clematis viticella cultivars in early spring, just as the buds begin to swell. Prune midseason cultivars that bloom in May and rebloom in September at the same time as late-blooming clematis.
Prune early-flowering clematis vines only when needed to remove all dead, diseased or damaged growth. You can also prune these clematis types to retain a desired shape or growth pattern.
Prune midseason double-blooming clematis to remove dead shoots and stems. You can prune these types of clematis back to the ground in spring, but then they won't bloom during the first flowering period in May.
Cut back late-flowering clematis vines to the nearest healthy bud that's about 1½ to 2 feet from the ground. Pruning these clematis types in this way each spring will promote healthy branching and flowering.
Select a planting site for your clematis that has full to partial sunlight. If you live in a warmer region, partial sunlight with shade in the afternoons is best. Large-flowered hybrid clematis prefer partial shade or a site with eastern exposure. The planting site should have fertile, well-draining soil with a neutral pH of 7.0 and plenty of air circulation around the clematis vine.
Beware of fungal stem rot and leaf spot diseases infecting your clematis. These diseases, along with clematis wilt, cause the vine to turn black, wither and die within a few days. If this occurs, cut the clematis back to the ground and destroy the vine parts. The clematis may regrow the next year if buds remain below-ground. Powdery mildew and pests like aphids, mites and slugs can also affect clematis.