If you buy a climber with lots of tangled growth, cut it back to about 30cm (12”) above the soil level, 15cm(6”) for clematis. Train the remaining shoots along individual lines until they reach the wall or support, and then spread them out so they will cover the space available. Even self-clinging climbers should be trained in this way and with ivies in particular you may need to temporarily secure the stems to the wall. Most established climbers do not need regular pruning other than to keep them in bounds. The exceptions are clematis & wisteria.
- Young wisteria tends to produce one or two main shoots, which twine upwards without branching. This is fine for a pergola but on a wall you want branching low down. Choose the strongest shoot, cut it back by half & tie it vertically. This is the leader.
- Cut any other shoots off at ground level. As side branches grow, train these sideways. These will go up at an angle, but you should be able to pull these horizontal in autumn. In the winter cut back the leader & main side branches by about a third. Repeat each winter until the wisteria has filled the available space.
- With established wisterias, they should be pruned twice yearly. Cut back unwanted growth in late July – early August to keep the plant in check. Then working your way along each stem side branch, shorten all the new side shoots to about six leaves. Ideally you should restrict the number of shoots to one every 18” or so along the main stem. In midwinter shorten the shoots you cut in the summer to only two or three buds to encourage bud formation.
Soil that is too rich can also hinder flower production & any form of feeding is generally unnecessary.
For pruning purposes, clematis falls into three groups:
- Spring & early summer flowering. This includes small flowering species, which flower by June. They do not need regular pruning but can be shaped over after flowering to keep them tidy. Every few years cut an old stem hard back to encourage new growth at the base.
- Early summer flowering (large flowered). — Florida, Lanuginosa, Patens. These flower in June & July on growth produced the previous year & again on new growth in the autumn. Prune about a third of the main shoots to about 30cm (12”) from ground level immediately after the first flush of flowers. New shoots can be trained in as replacements. If the clematis becomes overgrown cut them back hard after flowering or in February, which means the first crop of flowers will be lost.
- Late summer flowering (large flowered & species). Jackmanii,Texensis, Viticella.This group flowers from July onwards on new growth & include autumn flowering species.
Prune the stems back hard down to the lowest pair of buds above the previous year’s growth in February or March. Old or neglected plants, cut a third of the stems down to ground level.