Clematis are hardy vines with spectacular flowers that deserve a special spot in any landscape. They frequently are grown on mailbox posts, fences, trellises, and deck railings or mixed into perennial borders. Clematis prefer a higher soil pH, but they also grow quite well among rhododendrons and azaleas in acidic soils. A more important requirement is an organic, rich, and well-drained soil.
Plant clematis in a site that receives some good light, but not in full, hot sun. The hot sun fades the flowers and bakes the soil, harming the roots. Mulching and regular watering will reduce heat and drought damage.
Clematis cultivars vary in size, flower form, color, and time of bloom. Dwarf types reach only 24 inches in height, while others may grow to twenty feet or more. Clematis vines grow quickly and need pruning. Regardless of the cultivar, prune all dead stems after a hard winter. The objectives in pruning clematis are to maximize flowering and to manage the size of the vine. However, looking at all those stems tangled together can be intimidating. Once you understand the flowering habits of the type of clematis, pruning is really simple.
For pruning purposes, clematis are placed into three different groups based on their time of bloom. Early-flowering types bloom by early July on stems produced in the previous year, and two types of lateflowering types bloom in mid-summer on current season’s stems.
Group one consists of all the early-flowering evergreen species and their cultivars, such as C. armandii, C. alpine, C. cirrhosa, C. macropetala, and C. montana. Evergreen types are only winter hardy in Southern Maryland and the Eastern Shore. They are all early- to mid-spring bloomers. Prune them after the main flowering period has finished and remove all dead or damaged stems.
Group two consists of all the old-wood flowering types, including the double and semi-double largeflowered cultivars and the mid-season large-flowered cultivars. Some examples are ‘Miss Bateman,’ ‘Lady Londesborough,’ ‘Nelly Moser,’ ‘Henryi,’ ‘Marie Boisselot,’ and ‘Elsa Spath.’ Prune them after the main flowering period has finished. This group should not be pruned too hard or future flowering will be reduced. It’s safe to remove all dead or broken stems either during the growing season or after winter.
Group three consists of large-flowered, lateblooming cultivars. These all bloom on the current season’s wood and should be pruned in the early spring. Common varieties are C. viticella, C. recta, and C. jackmanii. This group requires severe annual pruning in early spring, cutting all the stems back to within 24 inches of the soil line. This hard pruning will stimulate vigorous new stem growth that produces many flowers. Very old declining stems may need to be removed completely at the ground level.
Type of Pruning
Essentially, you can give clematis vines either a “hard” or a “light” prune.
Author: Raymond Bosmans, Professor Emeritus University of Maryland, March 2011
Editor: Jeanine Smetana, University of Maryland Extension Master Gardener