Clematis are usually vining plants, although there are some bush versions. The plant directs the eye upward as it follows the numerous blooms on the vine. Clematis are grown for season-long flowers, some of which are the size of dinner plates. There are evergreen clematis and deciduous vines. Clematis bloom on either the current season’s growth or the last season’s growth. It is important to know which you have for proper pruning.
It is important to know the blooming habit of your clematis or you take the chance of cutting off all the wood that it blooms on in the next season. You will get green leafy growth but no flowers. If you do not know your plant’s habit, there are a few clues. Overall, the smaller flowering summer and early fall bloomers form buds on the new growth. The earliest clematis flowers start blooming in spring from older wood. The huge flowers arrive around June on last season’s growth, but may bloom again on new wood.
Early flowering species bloom in April to May. They bloom on old wood; prune them after they bloom to preserve the bud material. There is a general rule that states that blooms before June 15 are on old wood. These clematis are called Group 1 and are prone to cold damage. Laying the vine down and covering it with several inches of mulch can preserve them. After the blooms are finished Group 1 clematis are cut back to live new wood.
Hybrids are Group 2, and flower first on old wood and then on new wood. The blooming time is usually May to July on old growth. Late in summer, the second flowering occurs on the new growth. Prune in February or March, just to reduce dead stems and remove weak or damaged growth. Then cut the stems back to the first pair of green buds. This group can get leggy; so it may be cut back after bloom to 18 inches from the ground in an attempt to force lower growth.
This clematis flowers on the last two or three feet of the current season’s growth. In early spring, cut about 18 to 24 inches from the ground, just above a new bud. You can also wait until the buds break and then cut the vines back to the top most growth. This group of clematis is almost fool proof to prune and is the easiest of the clematis to grow. The late flowering clematis benefit the most from pruning, however. If they are not pruned the flowers are only produced on the very top of the plant.