How to Prune Clematis Plants

For pruning, clematis can be broken into three main groups:

• Group 1: These are early spring bloomers that flower on the previous year's growth (old wood). They are done blooming by mid- to late spring. Popular varieties in this group include C. armandii cultivars, C. montana cultivars, and C. apina cultivars.
• Group 2: These are spring and early summer bloomers. They produce flowers on the previous year's growth, as well as on new growth. Most of these are hybrids with very large flowers. This group includes cultivars of the popular Clematis patens species.
• Group 3: This group produces flowers on growth from the current season in late summer and fall. Popular varieties include hybrids, such as Jackman's clematis and 'Ernest Markham.'

If you don’t know which pruning category your clematis falls into, watch the plant for a season to take note of when and how often it blooms.

1. Prune Early Spring-Blooming Clematis (Group 1)

   This is a group that can be left unpruned during some years without much negative impact. But when you prune them, do so as soon as they finish blooming in the spring. Because these plants flower on old wood, you want to give them as much time as possible to develop for the next season. This generally means they should be pruned before the end of July.

   To prune, first remove any dead or damaged stems. Then, trim unruly outer stems back to woody main stems or near ground level. What you prune is really a matter of how you wish to shape the plant.

2. Prune Spring- and Summer-Blooming Clematis (Group 2)

   Clematis varieties in this group generally produce a heavy flush of flowers in the spring and then bloom again in smaller quantities later in the season. Annual pruning is essential. Without it the plants will get top-heavy and have fewer flowers.

   In late winter or early spring, prune all damaged or dead stems down to ground level. Trim remaining stems back to a point just above the strongest, most visible buds. Then, after the first heavy blooming is complete, prune back to a pair of buds about halfway down the stems. This pruning often will get you another period of blooming on new wood in late summer or early fall.

3. Prune Late-Blooming Clematis (Group 3)

   The late-flowering group produces flowers on the current season’s growth, which requires a different approach to pruning. These plants typically die back to ground level in the winter, and any old plant material left in place creates a disheveled mess.

   So in late winter or early spring, cut these plants down to about 2 feet from the ground. Most are vigorous growers—sometimes bordering on invasive—so be aggressive about pruning, and make sure to do it each year.

When to Prune Clematis Plants

The proper time to prune clematis plants depends on whether the plant flowers on growth from the previous or current season. The goal is to make sure you don't prune in a manner that eliminates or reduces the flowers, which is the main reason people grow clematis.

Clematis varieties that bloom on old wood should be pruned immediately after they are done flowering, which gives the plant plenty of time to grow new stems for next season. Varieties that bloom on new wood are best pruned when the plant is dormant—either in the late fall and winter or very early in the spring before new growth has begun.

Tips for Pruning Clematis Plants

Treat slow-growers cautiously, pruning just enough to shape the plant to your liking. The faster a clematis grows, the more aggressive you can be with pruning.

Also, don't be afraid to ignore pruning duties until you've witnessed a season or two of growth. Once you know the tendencies of your plant, it will become clear which pruning strategy to employ.

Finally, a few large, established stems can be left in place, even for varieties that bloom only on new wood. These stems form a framework around which new wood can grow.