Plant Doctor Archive

Pruning a clematis

CAN you please tell me how to prune a Clematis montana 'Rubens' which has now grown away from the fence it was originally trained on and is starting to smother a nearby tree?

WHY prune it at all? It will be a great sight in spring when covered in flowers, and climbing up a tree is what the clematis does in nature, so why interfere?

Seriously, though, if the tree is being completely swamped by the clematis, which can happen, you have a couple of options. One is to completely cut away all growth that is climbing the tree and try to restrict the clematis to the fence. You could do this in winter, but I'd be inclined to leave it until after flowering in spring, just to enjoy the display. You can hack into this type of clematis without fear of doing permanent damage. It will soon grow away again. To keep it under control from then on, cut it back each spring after it has finished flowering.

The second option is to try to thin out individual shoots that are climbing the tree in an effort to reduce the load but still retain the "wild" look. But often clematis shoots are so intertwined this can become quite a time-consuming task.

A point to bear in mind is clematis flower best in full sun and if shaded by a nearby tree will attempt to grow towards the light, hence climbing the tree. So it may be an idea to prune away overhanging branches from the tree to expose the clematis to as much light as possible on the fence, perhaps reducing the desire as well as the opportunity to climb the tree.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.