Pruning will help keep your clematis vines healthy. Pruning the dense tangle of stems opens the remaining shoots to air and light which encourages healthy growth and reduces the incidence of rot and disease. Cleaning out all of the unwanted growth and old stems will also have the obvious benefit of improving the visual appeal of your vine. Deadheading your clematis will also encourage additional blooms in the second wave if you have a group two variety.
Clematis are divided into three main pruning groups depending upon the characteristics of the plant. A simple guide to these three groups is given below.
Group 1 Clematis flower in spring on growth from the previous year. Prune your Group 1 clematis when they have finished blooming. This will allow the new stems more time to grow and set buds for next years display.
Group 1 clematis typically need very little pruning and how much you remove is dependant upon the varieties vigour. The highly vigorous varieties such as C. armandii can be cut back heavily whereas the slower growing varieties such as C. alpina and C.macropetala will need very little pruning. C.montana can be reluctant to re-sprout after being cut-back so avoid cutting these back to the old wood.
Group 2 Clematis bloom in late spring on last years growth and again in summer on the new growth.This group require a little more care when pruning as if you cut back too heavily after the first flush you will reduce the number of flowers on show in summer.
Prune back lightly to a set of strong buds in winter and remove any dead stems and trim to tidy the plant. After the first flush of flowers in spring, remove the spent flowers to encourage new growth and a stronger second flush in summer. Feed with a good quality liquid fertiliser after pruning to encourage growth.
Group 3 Clematis flower in summer on new growth from the current growing season. Pruning of group 3 Clematis is needed to prevent your plant ending up as a tangled mess of old and new growth and the blooms only appearing on some areas and not appearing in others. Prune your Group 3 clematis back to around 30cm above the ground or to a set of healthy, strong buds close to ground in early spring.