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Clematis Care

Pruning Clematis Vines

By: Sandy Feather 2006
Penn State Cooperative Extension

  
Q. I have a 10- to 12-year-old clematis vine that has lots of foliage but very few flowers. It has been this way since it first started to bloom. In the fall, I cut it back almost to ground level. It regrows vigorously every spring but does not bloom very much. What can I do to get it to bloom more?

A. It is advisable to prune all clematis annually to avoid them becoming bare on the bottom and carrying all of their flowers high on the plant out of comfortable view. The main object of pruning should be to encourage the plants to produce the maximum number of flowers for your enjoyment, as well as to keep some of the more vigorous types in bounds.
There is a good chance that your clematis does not bloom very much because you are pruning it at the wrong time of year.
  

 

When to prune Clematis
New wood or old wood variety?

How and when you prune clematis depends on when it blooms and its growth habit. Horticulturists divide clematis into three groups, based on their time of bloom.

Some species flower on the current year's growth, often referred to as "blooming on new wood."

Others flower from buds produced on last season's growth, which is referred to as "blooming on old wood." Still others flower on old and new wood. It is easy to look up the proper pruning group if you know the cultivar name or species of your clematis.


Clematis flowers


Clematis pruning groups:

Group 1 or Group A: Early-flowering species that generally bloom in April and May from buds produced on last season's growth (old wood). They should be pruned as soon as possible after they finish flowering. Avoid pruning them after the end of July, so they have time to produce next year's flower buds before winter sets in.

Start by pruning out any dead, damaged or weak stems. Then prune out the shoots that have flowered. You can also prune out more stems at their point of origin to thin out the plant and maintain a good framework of main stems that flower well within easy view. Avoid cutting into the woody main trunks.

Clematis in Group A include C. alpina, C. chrysocoma, C. macropetala and cultivars, and C. montana and cultivars.

Group 2 or Group B:

Large-flowered hybrids such as 'Nelly Moser' that bloom in June on short stems from last year's growth (old wood) and often flower again in late summer on new growth (new wood). Because you do get a few flowers after cutting the plant back so hard in the fall, it is likely that yours falls into this category.

This group of clematis should be pruned in February or March. Begin by removing dead and/or weak stems. Then cut the remaining stems back to the topmost pair of large green buds. This cut could be a few inches to a foot or more back from the stem tips.

Plants in this group have the tendency to become bare at the base as they mature. You can underplant with small shrubs or perennials to help conceal the bare stems. Alternatively, you can often force a flush of new growth from the base by cutting the vine back to 18 inches immediately after the flush of bloom in June.

In addition to 'Nelly Moser,' plants in this group include: 'Miss Bateman,' 'Lasurstern,' 'Duchess of Edinburgh,' 'Belle of Woking,' 'General Sikorski,' 'Mrs. N. Thompson' and 'The President.'

Group 3 or Group C:

Late-flowering species and hybrids, including sweet autumn clematis (C. terniflora). This group flowers on the last 2 to 3 feet of the current season's growth (new wood). Some types begin blooming in mid-June and continue into fall. They are easy to prune because you do not need to maintain any old wood. In February or March, cut each stem to a height of 1 or 2 feet. Although you will be removing good stems and buds, this treatment keeps these vigorous growers in bounds. In addition to Clematis terniflora, plants in this group include: Clematis x jackmanii, C. tangutica, C. viticella, 'Duchess of Albany,' 'Comtesse de Bouchaud,' 'Ernest Markham,' 'Lady Betty Balfour,' 'Madame Julia Correvon,' Perle d'Azur' and 'Royal Velours.'
  

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