Start from the bottom and work up from healthy pairs of buds located fifteen to thirty inches above the soil. Remove all old top growth that didn't die naturally over the winter. Many of these plants will add eight or more feet of growth during the growing season. Popular clematis pruned this way are Jackmanni, Niobe, Hagley Hybrid and Sweet Autumn. Many of the early blooming types will re-bloom later in the season if the spent flowers are removed.
Some people prefer to leave the seedheads, which can be decorative.
After pruning be sure to water, fertilize and mulch clematis for the summer. Occasionally, tie the stems securely to a trellis or support to prevent wind damage and a better floral display. If you have not grown clematis in the garden now is an excellent time to add them to your plant collection. Clematises prefer cooler soil conditions so plant where their roots will be shaded by another plant and mulch. Adding any of the varieties mentioned above would be sure to please in the garden.