Growing best in fertile, moist but well-drained soils, clematis vine leaves and flowers appreciate abundant sunlight. The showiest blooming types are herbaceous perennials that grow from buds on the lowest stems. Hundreds of varieties exist, some better suited to regions with colder winters or hotter summers. To better help gardeners know when and how to properly prune clematis plants, they are grouped into one of three cultivation groups.
Within the genus Clematis there is great variation of species, so discussion of pruning is complex and confusing. Horticulturists tend to group clematis species and cultivars on when and how they bloom. Early spring-blooming clematis types bloom from winter to early spring on last season’s branches. Summer-blooming types bloom in late spring and early summer from last season’s branches and again in early fall on branch tips of current year’s growth. Fall-blooming clematis plants bloom in summer and early autumn only on branches that grow that same year.
Early-spring clematis vines need to be pruned immediately after flowering ends in early spring. Cut back vines to lower healthy buds or leaf nodes to reduce plant size or tidy the plant in its space. Allow regrowth to mature across summer and fall. Flower buds begin to form on the stems in late summer, so pruning too late in the year removes the flowers expected later in late winter to spring.
Before growth begins in spring, prune away any dead or damaged branches from the winter. Trim back all other healthy, alive stems and branches back to where you see plump dormant buds. Make the pruning cut 1/2 inch above a bud so that one to three buds remain on the length of vine stem. These buds sprout in spring to produce flowers by early summer. Do not prune back vines or branches the rest of the year,as you risk removing flowers that may open in autumn.
Fall-blooming clematis vines entail the most straight-forward, simple pruning approach. In early spring before leaves appear, cut back all vines to only two plump buds. After proper pruning of these clematis plants, vine stubs about 6 to 10 inches tall remain above the ground. Do not prune back the new growth the rest of the year, as you will remove buds and flowers that open from summer onwards.
Use a clean, sharp-bladed hand pruners to trim clematis vines. If any branches die, break, or become riddled with disease, you can prune to remove it any time of year. Once fall frost kills herbaceous stems, don’t prune anything away as the dried plant material helps insulate tissue over winter. For example, extreme cold will damage outermost branch tips first, but lower buds and tissues are buffered. Pruning exposes lower buds and tissues to cold, making them the new outermost branch tips with increased exposure.