So far, it has been a spectacular year for clematis. The flowers have been stunning with many more to follow.
Clematis is a vine that can be grown on walls, on pergolas or in containers. Or it can be left to ramble through trees and shrubs. There are more than 600 named varieties of clematis and many more seedlings. Flower colors include pinks, purples, blues, reds, whites and even a few yellows, with bi-colored and double options as well. With so many choices, it is hard to know what to pick.
Clematis characteristics, categories
Most varieties are deciduous, but there are a few evergreen clematis, including armandii and cartmanii. There is a lot of diversity in flowers’ shapes, sizes, colors and forms. Flower shapes can resemble bells, lanterns, tulips, stars or
saucers. Flower size may be no larger than 1 inch up to 8 inches across. Some produce single blooms while others produce doubles. The flowers are definitely the showiest part of the plant, but many varieties have beautiful seedheads after bloom. While most clematis plants are vines, a few non-climbing varieties are grown as clump-forming perennials or small shrubs.
Not only do clematis vary in flower color and size, they vary by bloom time. Some bloom only in the spring; some bloom all summer; and some bloom in the fall. Clematis varieties are categorized into three groups: Group 1 (spring bloomers, which bloom on old wood only); Group 2 (repeat bloomers, which bloom on both old and new wood); and Group 3 (summer or fall bloomers, which bloom on new growth only).
There are many options, but here are some of the most popular:
Group 1— Armand clematis, which is evergreen and has white flowers; pink ‘Apple Blossom’; Clematis x cartmanii ‘Avalanche’; and white Clematis montana ‘Grandiflora.’
Group 2 — ‘Henryii’ with large white flowers and ‘Nelly Moser’ with pink-and-white striped blooms.
Group 3 — ‘Ernest Markham’ with magenta blooms and ‘Jackmanii’ with purple flowers. There are two fall-blooming clematis, commonly called sweet autumn clematis, which bloom in late summer to fall with hundreds of fragrant small white blooms. The native Clematis virginiana is well-behaved, but the non-native Clematis terniflora is quite invasive, so make sure you know which plant you are getting.
These are just some of the more common varieties, but there are many more, with new choices annually. Check local nurseries to see what they have available.
When planting clematis, choose a site with full morning sun or filtered sun. Most clematis, especially the summer-flowering ones, like bright light on their tops and a cool, rather moist area for their roots. To help keep the base of the plant and the roots cool and shaded, plant them where other plants can shade them; put a layer of mulch at the base; or plant on the north side of a trellis, and pull the vine to the sunny side. Although clematis can grow in full sun, the blooms fade quickly in strong afternoon sun. The plants tend to have more intense color if given some protection from the hot afternoon sun, but they will not flower well in the shade.
Clematis need a well-drained, neutral to slightly acidic soil. For strongly acidic soil, adding a little lime will help. Clematis vines are not too keen on having their root systems disturbed after planting. Don’t plant a lot of seasonal color around them where you are digging every year; clematis have feeder roots close to the surface. Some gardeners plant them at the base of other shrubs, letting the vine grow within the other shrubs for support; they bloom fine while adding a new dimension to the shrubs.
Fertilize clematis as they begin growing using a well-balanced fertilizer. Repeat again a month later. Clematis are not drought-tolerant, requiring regular watering through the growing season. Clematis climb by twisting their leaf stalks around supports, so it is necessary to provide some form of support when growing against walls and solid fences. Use a trellis or mesh for the clematis to twine around; lightly attach the vine with a soft twist tie. Clematis vines are not as flexible as many other vining plants, so use care not to break off a vine while getting it attached.
Proper, well-timed pruning of clematis vines stimulates growth, which increases the number of flowers and makes the plants more attractive. For Group 1, the spring-only bloomers, prune after they finish blooming. For Group 2, those that bloom repeatedly on both old and new wood, remove dead or weak wood in the spring as new growth begins. For Group 3, those that bloom on the new growth, prune fairly hard before new growth begins. Staggering the pruning heights can give a fuller vine with flowers from top to bottom. Don’t know which group your clematis falls in? Let it grow for a year, and time the flowering.
This may be the year of the clematis. If you haven’t grown any, try some. There are plenty to choose from.