Green Circle Growers Blog

How and When to Prune Clematis

Green Circle Growers - Tuesday, July 05, 2011

A beautiful vining plant that produces large, colorful flowers from late spring through fall, Clematis is a garden favorite (see our previous post). With proper pruning this old-fashioned perennial will produce years of thick, lush foliage and abundant blooms. But there’s the rub. After a few years of improper or negligent pruning, clematis vines can become top heavy, the greenery and blossoms bushing out above unattractively barren stems. Unfortunately, pruning clematis is not a simple matter. This flowering vine is divided into 3 pruning groups based on peak blooming period and whether flowers are set on old or new growth.

Use the following guidelines to determine which pruning group your clematis falls into and prune accordingly:

Group 1: Vigorous spring bloomers that flower on old wood, Group 1 varieties include Alpina, Armandii and Montana. Because clematis in this group flower on the previous season’s growth, vines should be pruned as soon as they finish blooming. If pruned too late, you run the risk of removing next year’s flower buds which will result in greenery but few blossoms next spring.

Group 2: These hybrids produce large flowers on old wood, providing a stunning display from early to mid-summer. After flowering, cut clematis in this group back to a height of 18 inches to promote the development of more and sturdier stems. Allow new growth to develop unimpeded over the summer. In February or March give the tops a very light pruning. Group 2 clematis include Miss Bateman, Henryi and Nelly Moser hybrids.

Group 3: Flowering entirely on new growth, group 3 clematis include the popular Jackmani, Perle d’Azur and Duchess of Albany varieties. Because flowers form on new stems produced during the current growing season, group 3 clematis should be hard pruned by cutting stems back to a height of 18 inches in late winter or early spring.

Photo by: tobyotter