Group 1 (None)- This is for the species that produce their flowers on short flower stalks directly from a leaf axil bud, in general, on stems produced the previous season, which were hardened by cool autumn weather. This group consists of the evergreen species and their cultivated forms, the alpina and macropetala types and the Montana group. These produce their flowers directly from the old stem and should not be pruned until all flowering has been completed. Remove all dead and weak stems after blooming. Tie all stems into position immediately after pruning.
Group 2 (Moderate)- Consists of the early large-flowering cultivars, the double and semi-double and the mid-season clematis. These will produce their flowers on the old or previous seasonís stems. The pruning and tying of stems should be done in the early spring when weather permits. Remove all dead and weak stems, and trim the remaining stems to where a strong pair of leaf buds appears. All the remaining stems should be tied in a position that gives sufficient space for new growth.
Group 3 (Hard)- This group bears flowers on new growth each year and in most cases each stem produces several flowers. The old or previous seasonís growth dies away naturally each winter; therefore, all old growth must be removed to allow the current seasonís stems room to grow, giving the plant a fresh start each year. Prune in late April or early May depending on weather conditions. Pruning consists of removing all top growth down to where strong new leaf axils appear at ground level.