The goal, when pruning clematis vines is to get the best display of flowers on the plant that you can. The type of pruning you do depends on when your plants flower. If you don’t know which kind you have (spring, summer or twice-blooming), watch your vines for a year to see when they flower, then use one of the following methods:
Always give clematis regular water and a good, steady supply of nutrients. Try not to let them dry out, and apply a complete liquid fertilizer monthly during its growing season.
The following pruning methods are for clematis 3 years old and older:
Group 1 or A
No pruning required. This group is the early flowering species that produce blooms on previous year’s growth (‘old wood’). If pruning is needed to remove dead and unsightly foliage, prune right after flowering (within a month of flowering). This allows the vine to make new growth that produces next year’s flowers.
Group 1 (none) – are varieties that flower only on growth produced the previous year: Clematis montana,Clematis alpina and Clematis macropetala. They are generally not pruned at all, but if it is necessary to prune some overgrowth, cut immediately after flowering, usually not lower than 1 m above the ground.
Group 2 or B
This group includes the early, large flowered cultivars that bloom in the spring and again in the fall. They bloom on previous year’s growth (actually on short shoots from ‘old wood’) and should not be pruned except for deadwood. It is best to wait until late spring to see if the vines are indeed dead before pruning since new sprouts can emerge from some very dead looking vines. The number of later flowers can be increased if the seed heads from the first flowering are removed right after the blooms drop their tepals.
Group 2 (light) – are the large-flowered varieties that begin to bloom in May or early June with the first flush of flowers appearing on the previous year’s growth, followed by a smaller flush on new growth. Pruning should consist of cutting shoots at a height of 100 – 150 cm from the base (the younger a plant the lower it should be cut). This is a safe way of pruning if we are unsure which category our plant falls into.
Summer and Fall Flowering Clematis
Group 3 or C
This group is the late blooming species and cultivars. These plants bloom on new wood and should be pruned back severely every year in late winter to about 12 inches of soil level. Group 3 (hard) – are later flowering species and varieties that bloom on new growth from the end of June to July e.g. cultivars from Viticella Group and Jackmanii Group. These should be hard pruned above second or third set of the buds, 20 – 50 cm from the ground. This pruning pattern should also be applied to vigorous vines if you want to reduce their growth:Clematis Orientalis Grup, Clematis tangutica. As for herbaceous perennial clematis and cultivars from Texensis Group remove all dead stems just above the base, cut the rest 5 – 10 cm above the ground.