Pruning your established clematis:
Clematis are grouped into three groups for pruning:
- Group 1: no pruning. This includes C. alpina, C. macropetalla, C. montana and the evergreen C. cirrhosa and the C armandii groups. If you want to prune any of these varieties because they have outgrown their shape then they must be pruned immediately after flowering although any heavy pruning should be spaced over two or three seasons rather than done in one go.
- Group 2: light pruning. This includes large-flowered varieties which produce their main flush of blooms in May and early June on stems made the previous year so pruning is limited to cutting out dead or weak shoots in February. The best way of doing this is to work your way down from the top of each stem until you reach a healthy bud and then prune just above it. Also remove any dead or diseased wood. Heavier pruning will result in no flowers. When the early flowers have finished you can prune back some of the flowered shoots to promote new growth and also cut back a plant that has got untidy or overgrown.Examples of group 2 varieties include C. ‘Nelly Moser’, C. Jackmanii and C. Beauty of Worcester.
- Group 3: hard pruning. This includes the late-flowering hybrids and the small-flowered viticellas, orientalis and texensis groups which all flower on the new season’s growth. Prune in February by starting at the bottom of the plant and working up to the first healthy bud. Prune above that bud and remove everything above the cut. Examples of group 3 varieties include: C. ‘Etoile Violette’, C. tangutica, C. Ernest Markham and C. Princess Diana.
If you don’t know what type of clematis you have then there are a couple of simple rules to help you out:
1. Don’t prune clematis which flower on the previous year’s growth, i.e. before June in central England.
2. Hard prune clematis which flower on the current year’s growth, i.e. from June onwards.
Finally – all newly planted clematis should be hard pruned in the first early spring (February or March) after planting. Remove the top growth by pruning just above the first set of live buds on each stem which will cause the plant to grow into two stems or shoots which should be pinched out once or twice during spring.