Possibly the toughest part of growing Clematis is the pronunciation of its name – CLEM-uh-tis.
Also known to gardeners as “vase vine,” “leather flower,” “traveler’s joy” and “virgin’s bower,” clematis made its original debut in American gardens back in the early 1800s. Today nearly 300 species of clematis exist worldwide.
Believe it or not, clematis is a cousin to both the peony and buttercup; all belong to the family Ranunculacea. Depending on the species and hybrid, the plants’ hardiness can extend as far north as a zone 3 and their life expectancy is long.
Clematis are masters at using their “twining petioles” or “tendrils” – numerous threadlike stem protrusions that twist and curl around their chosen mode of support. They’re perfect when planted at the base of a trellis, piece of lattice or when allowed to petitely weave throughout a climbing rose or cascading wisteria.
Try adding vertical interest to your yard by coaxing a clematis up an otherwise drab lamppost, retaining wall or split rail fence.
Clematis prefers a sunny location where the soil is well drained, enriched with organic matter and a pH near 7.0. Once the location is chosen, you’ll want to plant so the crown is a good 2-3 inches below the surface of the soil.
For healthiest plants, prune all varieties back to a 12-inch height at planting time. If you plant deep and prune rigorously, development of new shots and a thickening of existing ones will be encouraged. A stronger start means a longer life.
Clematis are heavy feeders; upon planting, mix in a complete fertilizer that is high in phosphorus (second number) to promote stem and flower development; water deeply and water again once a week until late fall. Come fall, fertilize with bone meal or super-phosphate for a slow winter feed and reapply a complete high phosphorus fertilizer in spring.
Diseases and insect problems are minimal; most threatening is the disease wilt. If you get it, remove infected stems at ground level. If the vine was pruned back when planted there’ll be plenty of stems to carry on. Discourage mildew from forming by providing good air circulation and purchasing resistant varieties.
Prune only when it’s time
Here’s where folks get antsy: pruning. But, like shrubs, once you acknowledge the plant’s bloom time its pruning schedule falls neatly into place.
Clematis are classified in three groups based on their bloom time, and are pruned accordingly.
Group A: Early-flowering; April and May. Blooms on previous year’s growth.
Prune immediately after flowering, only to remove dead stems and occasionally thin to rejuvenate old plants. These are an excellent choice for covering large areas and growing into trees.
Group B: Large-flowering, early summer and again late summer.
Blooms on side-shoots of previous year’s growth. Prune in late winter, removing weak/dead stems at ground level. Trim all remaining stems back to the uppermost pair of plump buds. Doing so will encourage side growth and more flowers for the following year. Don’t prune below the top buds because you’ll be pruning “old” growth where flower buds set. Prune below the buds only if rejuvenation is necessary due to vine legginess.
“Jackmanii,” “Henryi,” “Rubra” and “President” are commonly grown examples.
Group C: Late-flowering, summer and fall. Blooms on new growth. Prune in late winter, removing dead stems, careful not to damage newly emerging shoots. Cut all remaining stems to around 12 inches above soil line, leaving two sets of vigorous buds/stem. This will encourage new shoots and bushier growth from remaining stems to develop. The more new growth, the more flowers.
Try C.paniculata, also known as Sweet Autumn.
