Question: Our spring-blooming clematis vine has grown tall and seems very healthy, but it blooms mainly at the top. The bottom six feet has very few blooms and not much foliage this spring. Can you tell me why?
Clematis flowers clambering over a sturdy trellis or other support are a lovely sight each spring. When this woody flowering vine gets too top-heavy, with all the flowers at the top and bare stems at the bottom, the problem has to do with pruning – or lack of it. Early-flowering clematis blooms in spring from buds formed last season. Plant experts recommend pruning it each year to help the plant produce the maximum number of flowers. The time to do that is as soon as you can after it finishes blooming to allow time for new growth to produce flower buds for next year.
Horticulturists writing for a fact sheet from Ohio StateUniversity say that sometimes you can cut back into older wood of old, neglected plants to encourage new buds to break. The vines are most likely tangled, so when you prune, make cuts carefully, and train the stems to cover the maximum are on their support.
Note also that there are other varieties of clematis that bloom a bit later, on new growth, and those varieties should be pruned in the winter.
In general, here is what clematis needs to thrive: Loose, fast-draining soil that is high in organic matter, and regular water. Gardeners like to say that clematis prefers to have its head in the sun and its feet in the shade, so provide a thick layer of mulch to keep the roots cool. You can also plant a ground cover such as mondo grass around the base of the clematis vine.