Group 1 Clematis flower in spring on buds from last year's growth. They actually don't need to be pruned at all but you may want to tidy them up from time to time. The best time to prune them is just after flowering. Shape them up or remove crowded or damaged branches. You can also guide new growth to a new position by trimming and tying branches at this time.

Group 2 Clematis begin flowering in early summer from last year's growth as well as flowering later on short canes from new growth (in most cases). These should be pruned in spring before new growth begins. Look for fat, healthy buds on sturdy branches. They usually begin 1 to 2 feet down from the top of the vine. Make your cuts just above these healthiest buds. You may notice that you are cutting away some healthy canes, but you will be giving preference to the buds that will produce the best growth and flowers for you. At this time, trim away crowded and damaged branches, too.

Group 3 Clematis flower later in summer and into fall. They form flowers on new growth each year. For the best display and neatest look, they should be pruned back hard each spring to about two feet off the ground. However, if you are training one of these into a tree or onto an overhead arbor they should be left much longer. Look for fat, healthy buds on sturdy canes and make your cut just above them. The branches may be guided and tied to new positions now also.