Clematis are the easiest to prune, since you basically cut the whole thing down! ... This means that each year in March you should prune back all the stems to just about 12 inches off the ground to make way for the new growth. This group will come back strong and will bloom on the new wood each year.

When should clematis be cut back?

Prune your large flowering clematis during the spring, when the plant is still dormant. Remove any damaged, dead or weak stems, cutting back to a pair of healthy buds. Avoid heavy pruning at this stage as you may get less early flowers.

What happens if I don't prune clematis?

If left unpruned, clematis vines become overloaded with decrepit stems that produce few flowers.