Clematis, the Cadillac of vines

Warsaw Nike  vjs

Warsaw Nike  vjs

You say clem-MAT-tis and I say clem-MAH-tis.

Don’t call the whole thing off, since we’re both talking about a most worthy subject, the aristocratic Queen of Vines. A relative newcomer to American gardens, clematis wasn’t widely cultivated here until the last decades of the 20th century, when international and national societies were founded to promote its virtues. (And by the way, these societies say the correct pronunciation is CLEM-a-tis.)

The vine first came to notice in Britain and Europe in the mid-1800s, when plant hunters spurred an enthusiastic round of hybridization with species collected in the Far East, the New World, Australia and New Zealand. Today, there are well in excess of 3,000 species and cultivars from which to choose, and modern hybridizers are constantly introducing still more selections.

True, the plant has a reputation for being finicky. Interest fell precipitously in 1880 when growers encountered one of its chief faults, a fungus disease now known as clematis wilt that can cause sudden die-back of flower-bearing stems. The disease decimated commercial British stock, which wasn’t rebuilt until after World War II. Wilt still can occur, but certain species are immune, and breeders have been working on greater resistance to this scourge.

Clematis belongs to the same family as buttercups and peonies, but shows a greater variation in habit and flower form than either of these familiar species. There are small flowered clematis, large flowered kinds and even some that are more bushy and upright than vine-like. Flowers can be wide-open, tubular or bell-shaped, and while there are a few exceptions, like the yellow ‘Orange Peel’ clematis, the color range generally runs from white, pink, rose and red through blue and purple.

For the gardener who meets their sometimes exacting requirements, there is no more spectacular sight than a clematis in luxuriant flower. The vine can get big — 12 feet is not uncommon in the large-flowered types, and some of the species, including the spring blooming Clematis montana and the frothy, fragrant sweet autumn clematis, can easily engulf a small outbuilding.

Hunda/Flickr

Hunda/Flickr

Unlike some vines, which glue themselves to supports with holdfasts or twine themselves through any available support, clematis hangs on with curling leaf stems, much in the way of sweet pea vines. Some gardeners use wire mesh, or allow vines to clamber through trees and shrubs, where branches provide the slender supports around which tendrils might wrap themselves.

Once you’ve chosen a vine — and this may be the hardest part, given the vast number of options — spring and fall are ideal times to get a clematis settled in the ground. Most want a site with at least six hours of full sun, but pastel varieties will hold their color better in filtered light. The ideal would be bright sun during the morning hours and light shade through the afternoon.

Clematis, like some lilies, thrive with their heads in the sun and their feet in the shade, which is another way of saying that despite their need for sunshine, they want a cool, moist root run. This can be accomplished by planting a shallow-rooted perennial or annual at their base, situating them behind shrubbery or mulching with three or four inches of organic material.

Even if the new and diminutive plant seems hardly to call for it, experts advise gardeners to excavate a sizable hole — no smaller than 18 inches deep and wide, and 24 inches would be even better. Smart gardeners get them off to a good start by providing a loosened soil, liberally amended with compost, dehydrated manure, peat or rich topsoil.

A soil test is not a bad idea — if your soil is quite acid, you may need to add lime to keep the soil on the slightly alkaline side. And bear in mind that clematis are heavy feeders, benefitting from weekly fertilization.

It isn’t the initial pruning that stumps many clematis growers, but maintenance pruning in subsequent years. To accomplish this properly, establish to which of three groups your clematis belongs. (Hanging onto plant tags and labeling your collection are very good ideas.)

Group I, which includes vigorous spring bloomers, should be pruned lightly after they flower to remove weak or dead stems and to keep them in bounds. Group II, encompassing early and mid-season large flowered types (generally blooming before June 30), should be pruned in late winter or early spring; working down from the tips, prune just above the first pair of live buds. Group III, including late-flowering species and hybrids, will eventually become bare at the base and flower only at the tips. That’s okay if they are trained into a tree or shrub, but otherwise these should be pruned in early spring to about 12 inches from the ground.

If clematis wilt strikes, all you can do is prune away and dispose of affected stems and hope new shoots appear at or below the soil line. Wilt rarely affects the species clematis or hybrids derived from Clematis viticella, and it seldom kills the plants outright. Slugs, which chew leaves and flowers, and earwigs, which attack blossoms only, can be pests.

Clematis are adaptable even if you couldn’t call them truly low maintenance. Keeping them happy requires no more than we’re willing to go through for other plants that captivate us with a big payoff of garden-enhancing blossoms. Grow them well and you’ll understand why clematis is the most coveted vine the in the garden.