Growing, Pruning Clematis

GROWING TIPS

Clematis falls somewhere between complicated and carefree, but the results are worth it. For good growth, the plants require these five things:

• About six hours of sun.
  
• Shaded roots.
  
• Good drainage.
  
• Plenty of fertilizer.
  
• Proper pruning.

Some large-flowered hybridized varieties can suffer from clematis wilt, in which the plant seemingly collapses overnight. If that happens, experts say to cut the plant down to the ground and treat it with a fungicide such as penconazole. If the clematis was planted deeply enough, new shoots should appear and the plant will rebound.

When planting, be sure that the soil is neutral, although lime should be added to correct acidity. Plant clematis 2 inches deeper than the pot it arrived in to help encourage root growth.

Avoid clay soils or areas that get wet in winter -- a fatal condition for clematis. A top dressing of manure in the spring is a good idea, and during the growing season, weekly doses of nitrogen-rich liquid fertilizer are recommended. Clematis doesn't climb by itself: Be sure to provide the plant with adequate support.

PRUNING TIPS

Pruning differs for the three classes of clematis:

A -- Montana rubens and some large-flowered hybrids such as 'General Sikorski' and 'Mrs. Cholmondely' flower on "old" wood, last season's growth. Prune only the dead wood in early spring. If in a few years the plant becomes an overgrown tangle, prune it back hard right after early summer flowering, so there's plenty of time for growth for next year.

B -- Clematis that flowers on both old and new wood -- 'Henryii' and 'Will Goodwin' are two examples -- requires light pruning in early spring to remove dead and weak wood. But don't overdo it because the flowers will be produced on the old wood. It will bloom a little later than the "A" group, in early to mid-June, and later, less spectacularly, in the fall. Some gardeners choose not to prune at all, for fear of mistakenly removing the old wood.

C -- 'Jackmanii' and sweet autumn clematis are the best-known examples of this type, which requires hard pruning back to 2 feet every spring, even if the new shoots look green and healthy and loaded with buds. A tough cutback will invigorate the plant to produce even more flowers.

(Note: Is your new clematis spindly and lackluster? The first year, keep it pruned back to 2 feet, regardless of pruning category, to encourage branching and development of side shoots.)

Sources:

• American Clematis Society: www.clematis.org
  
• Completely Clematis Specialty Nursery, Ipswich, Mass.: www.clematisnursery.com
  
• Donahue's Clematis Specialists, Faribault, Minn.: www.donahuesgreenhouse.com
  
• Good how-to site: www.homeofclematis.net
  
• Online forum to discuss clematis problems: http://forums.gardenweb.com/forums/clematis