By now, Clematis are in full leaf. If you are puzzled about how or whether to prune, relax. These vines will show you if you pay attention. In spite of the fact that Clematis are divided into three classes and each is supposed to be pruned differently, I find that these vines will show you if you pay attention.
You can almost always see the difference between the dead part of the vine – it’s beige and the growing part – the leaves obviously but also the stems – are green.
The spring flowering Clematis bloom on old wood, i.e., the previous year’s growth, so you should prune very lightly to remove deadwood and neaten but that’s all. If the Clematis is outgrowing its space, wait until after it blooms to prune.
The large, summer flowering Clematis bloom on both old and new wood so I merely cut off the deadwood unless it is serving as a vehicle to which the new growth will attach itself in order to climb where I can’t reach. If the Clematis is outgrowing its space, you can prune in early spring but should not expect it to bloom until later in the summer or even early fall.
There are some small bell- flowered, summer blooming Clematis so prolific that they need to be cut back ruthlessly. Clematis texensis, unlike many others, withstands heat and dry conditions although it is perfectly happy in average conditions. Cut it back to 12” in early spring because it grows very quickly. This Clematis is almost like a bush rather than a vine but needs support unless you want to let it sprawl on the ground like a groundcover. There are several cultivars: ‘Duchess of Albany’ is pink, ‘Princess Diana’ is a more intense pink, ‘Sir Trevor Lawrence’ is a deep pink, almost cherry red, and ‘Gravetye Beauty’ is the truest red of all Clematis.
The prolific fall bloomers like Clematis terniflora (Sweet Autumn Clematis) and
Clematis tangutica and orientalis (Golden Clematis) will easily grow ten to twenty feet in one season so I usually prune them back severely, leaving only a foot of growth.
Many Clematis require full sun to bloom prolifically; however, the spring blooming species prefer partial shade or morning sun only. There is an outstanding book on Clematis, Making the Most of Clematis, by Raymond Evison that specifies the type of light preferred by each species and cultivar. Although it is out of print, you may be able to find a copy by searching the internet.
The world of Clematis is vast. Enjoy it!