How and When to Prune Your Clematis

With their gorgeous vines and showy flowers, the clematis is a favorite among many gardeners. Although these perennial vines don't typically need much maintenance, established plants do benefit from occasional pruning, which helps promote flowering, contain growth, and keeps them looking neat and tidy. Some clematis cultivars are more low maintenance than others. When and how you should prune yours depends on the type you're growing.

Pruning Young Vines

To help plants develop sufficient shoots and stems and ensure good displays of flowers in the future, young clematis vines should be cut back to 12 inches above the ground the second spring after being planted. The third spring after planting, they should be cut back to 18 inches above the ground. After that, the vines are considered established and should be pruned according to the group they belong to.

Determining Which Type of Clematis You Have

If you're unsure of what type of clematis you have, simply take note of when it flowers so that you can fit it into one of the three pruning groups below. As a general rule, if your clematis flowers before July, then treat it as though it belongs in group 1 or 2. If it flowers after July, assume that it falls into group 3. You may also want to try identifying it using Clematis on the Web. The website features a searchable database of approximately 3400 clematis varieties as well as 3500 photographs of 1400 different cultivars. www.clematis.hull.ac.uk

Pruning Established Plants (plants in the ground at least 3 years)

Group 1: The Spring Bloomers--Minimal to No Pruning

Group 1 contains small-flowered clematis that flower early in the year (late winter to late spring). These clematis flower on old, woody stems (growth made from the previous season) and typically don't need any pruning. Cut them back only when they become congested or overgrown. This should be done right after flowering (no later than midsummer) to avoid removing next year's flower buds, and should be carried out gradually over several seasons.

Examples of clematis in this group include: C. alpina and its cultivars, C. armandii, C. cirrhosa, and C. macropetala and cultivars, and C. Montana and cultivars. Note: In colder climates, gardeners may find tender varieties (like montanas) naturally pruned to the ground each year due to sub-zero temperatures.

Group 2: The Repeat Bloomers--Light Pruning

Clematis vines in group 2 are the large-flowered hybrids that flower in early summer, and sometimes flower again with a lesser flush in the fall. They produce their flowers on the short side shoots of old wood, and should only be pruned to remove dead wood. Because new sprouts can emerge from dead-looking wood, pruning clematis in this group can be tricky. Wait until early spring, before the new shoots start to grow, to determine whether or not the old wood is actually dead.

If so, cut stems back by roughly one-third, to just above a pair of vigorous-looking buds. Just a few examples of the many clematis in group 2 include: 'Asao', 'Daniel Deronda', 'Duchess of Edinburgh', 'Henryi', 'H.F. Young', 'Liberation', 'Marie Boisselot', 'Moonlight', 'Nelly Moser', 'Niobe', 'The President', 'Silver Moon', 'William Kennet', and 'Vyvyan Pennell'.

Group 3: The Late Summer and Fall Bloomers--Hard Pruning

Clematis vines that make up group 3 are both large-flowered hybrids and smaller-flowered species that bloom in late summer or early fall. These clematis produce flowers on the current season's growth and need to be pruned hard in winter or early spring, before new buds start to develop. If not pruned hard annually, clematis in this group will soon develop long woody stems and few flowers.

Cut back all previous growth to a bottom pair of buds where you would like the current season's growth to begin-usually to at least 12 inches above the ground. Examples of clematis in group 3 include 'Comtesse de Bouchaud', 'Ernest Markham', 'Gipsy Queen', 'Hagley Hybrid,' 'Jackmanii', 'Perle d'Azur', C. tangutica and cultivars, 'Ville de Lyon', and C. viticella and cultivars.