By Kim Wilson
Though they seem inseparable, in truth, they are not like love and marriage. You can have one without the other. There are scores of ways to use clematis in the landscape in all of its forms. And that purple jackmanii, introduced by Jackman and Sons Nursery more than 100 years ago, is only one of hundreds of varieties of clematis that come in a rainbow of colors and many different shapes and sizes.
Ask Bing Steffen. His company, Arthur H. Steffen, Inc., the largest clematis grower and hybridizer in the U.S., sold half a million or so clematis plants last year and 85% of them were not jackmanii. Steffen's decision to begin offering its 200 varieties directly to gardeners this year for the first time will effectively quadruple the number of cultivars readily available, making it easier than ever to discover the possibilities of clematis.
The range of flower shapes, sizes and colors is amazing for a single genus of plants, too. From the diminutive, delicate-looking bell-flowers of C. alpina or C. macropetala to the almost gaudy blooms of the hybrids (a large group of cultivars resulting from the crosses of several species), the selections go far beyond shades of purple to cover, minus orange, almost the entire color spectrum.
Among the dozens of handsome and useful vines available to American gardeners, Steffen feels that none comes close to having the combination of characteristics that makes clematis a desirable plant for almost any garden. "I think clematis is a very forgiving vine," he says. It doesn't grow rampantly (with the possible exception of the sweet autumn clematis), and it climbs by twisting petioles, rather than by structure-damaging holdfasts or by twining, plant-choking stems. By choosing several cultivars, "you can plant a display that would start in May and go right through until frost. There aren't many plants that will do that," Steffen asserts.
Most clematis species and cultivars are hardy to at least -35 degrees F (USDA zone 4) and will grow almost anywhere in the country. Reliable perennials, they have been known to live for 50, even 100, years or more. Most, however, with the exception of several tender evergreen species, will be short-lived in the Deep South (zones 9 and 10). Steffen says that he has some customers in southern California who grow them as bedding plants by the pool and simply replace them when they have bloomed themselves to exhaustion.
Growing Tips
Clematis has a reputation for being difficult to grow, but it's actually easier than you might think. "Usually the biggest problem is not giving them enough water the first year," says Steffen. Initially, new vines should receive the equivalent of half a gallon of water per week throughout the growing season. Once plants are established, you only need to water them weekly during dry spells.
As with most garden plants, clematis appreciates a soil as close to the loamy, friable ideal as you can get it. The soil pH should fall within a range of 6.0 to 6.5.
To plant, (spring is the prefered season), prepare a hole at least one foot deep and wide and mix in some compost or well-rotted manure, peat and two handfulls of bonemeal. Set the clematis so that the crown is slightly below the soil surface to encourages the growth of multiple shoots. As Steffen explains, "It will give you a fuller plant down the road." The first winter after planting, prune all clematis varieties six to 12 inches from the ground.
Steffen doesn't recommend mixing any fertilizer into the hole. But beginning when the plant is 18 to 24 inches tall, water with a liquid chemical or fish emulsion fertilizer every two to three weeks.
The adage, "warm top, cool roots" applies to clematis, so keep the base of the plant shaded with a two-inch-thick organic or pebble mulch. English gardeners traditionally use shrubs or paving stones to shade the root zone.
Planting and training to encourage multiple shoots is good insurance against clematis wilt. Steffen, like several other clematis experts, believes that it's primarily a physiological problem. "The plant grows so vigorously in warm weather that the roots can't supply the nutrients to the top," he explains. He has also frequently found cases of so-called wilt that were a result of the wind or an animal breaking the somewhat brittle stem.
Should a young plant wilt, water frequently with a liquid fertilizer to encourage new shoots to develop from buried nodes. Clematis is otherwise generally free of serious disease or pest problems.
Landscaping and Training Ideas
"There are so many ways to use clematis, it's just a matter of using your imagination," says Steffen. Posts and trellises are obvious choices, but he would like to see these vines used more often in a natural setting, rambling through shrubs and trees. A thoughtful pairing can nicely extend the attraction of both. "We've got Exbury azaleas that bloom brilliantly in the early spring," he says. "Then, a little later, the clematis will grow up and bloom, using the azaleas for support."
These adaptable vines also make an attractive specimen in a large tub equipped with a trellis, provided the tub is shaded and the plant is out of direct sunlight. On a patio or deck, one can view the magnificent flowers up close, where they're most appreciated.
Since the vines climb by twisting leaf petioles, they won't hug a post, wall or trellis without help. Steffen has hit upon what seems like the perfect solution: clear, nylon fishing line. Simply peg a strand or two into the soil near the base of the plant, tie the other end to the support, and, with a little encouragement, up the line the stem will go.
The dozens of small-flowering clematis varieties, with their bell-, lantern- and saucer-shaped blossoms, offer even more creative options for the landscape.
For scent near a patio or an open window, Steffin recommends three: C. maximowicziana (formerly C. paniculata), the sweet autumn clematis, a vigorous grower that bears small cream-colored blooms from September through October; C. montana 'Wilsonii', with creamy- white flowers in early summer; and C. davidiana, a nonvining, herbaceous perennial with clusters of late summer-blooming, hyacinth-like flowers that hummingbirds love.
A heavily scented species for southern gardeners (zones 7 to 10) is the evergreen C. armandii, with handsome rhododendron-like foliage, excellent for covering walls and fences.
You might try the early-blooming C. alpina or selections 'Ruby' or 'Willy' which grow no taller than six to eight feet, in a rock garden setting. C. macropetala 'Snowbird', with white flowers and fluffy seedheads, is even more diminutive at three to five feet.
To cover a wall, fence or other structure, plant one of the heavy growers like sweet autumn clematis or C. spooneri, which easily attain 20 feet or more. The lemon-yellow lantern-shaped flowers of C. tangutica, another large plant, would be quite a sight in late summer festooning a fieldstone wall and perhaps reaching into the branches of a Japanese maple.
'Betty Corning' is covered with a multitude of azure-blue bell-shaped blooms for almost three months from late spring through midsummer and deserves a prominent place on a deck railing, a patio trellis or even a high stump.
Once you get started with clematis, it's easy to get hooked. A wholeheartedly blooming clematis vine in all its glory is an unforgettable sight. 'Henryi,' with its huge, elegant flowers, satiny white with blood-red stamens, put on a stunning show on my front porch this past spring, with continuous bloom for over two months. I was fairly impressed with its several dozen blossoms, but, according to Steffen, a mature 'Henryi' at his home last spring was covered with literally hundreds of flowers -- you couldn't see its foliage or the post it was trained to. Now that's something to look forward to!
Special Handling
Late spring flowering clematis cultivars bloom in spring on last year's growth and most of them often bloom again later in the season on new growth. They don't need regular pruning. If, after several years of unbridled growth, the plant is starting to get a little out of hand, you can selectively trim some of the vegetative shoots back in early spring, after the flower buds have formed.
If you want to get fancy, there are a couple of neat techniques you can try. Prune the entire plant back to within two to four feet of the ground and you'll sacrifice the spring show, but you'll be rewarded later in the season with a heavier summer bloom than you would normally get. With the second technique, called relay pruning, you cut half the plant down and leave the other half intact. The unpruned half provides the big early blooms, while the other half shoots up and produces summer flowers. The following winter, reverse the procedure. This technique gives a fuller-looking plant with less bare stem showing.
Summer-flowering cultivars flower throughout the summer on new wood only and may be pruned back hard to a height of four to six inches in midwinter, as the buds start to swell. You'll have a vine covered with blooms from top to bottom. If you don't prune, or prune back to three or four feet, the vine will resume growing where it left off (or where you cut it off), and the flowers will appear higher up on the new growth. It does no harm to the plant to leave it unpruned.
Clematis Shortage
Arthur H. Steffen, Inc. supplies about 50% of the nation's clematis to retailers and mail order companies. And has just put the finishing touches on their first retail catalog for spring sales. But this spring, Steffens has no clematis for sale. The culprit was contaminated Benlate fungicide. Steffens' has taken measures to rescue the affected plants. Though they look promising, Bing decided to do the right thing. He's holding them back to make sure there's no aftereffects of the poisoning. They're still sending out catalogs this spring, and will be filling orders in the fall. There are, of course, other clematis available. Though it can be assumed that foreign plants are free from contamination. Those grown domestically may or may not have been affected. Let the buyer beware.
Kim Wilson gardens in Emmaus, Pennsylvania.
Provided by NGA
A Fine Vine: Clematis
The two seem to be inextricably linked in every neighborhood in America. Bold, grape-purple, propeller-shaped flowers twining over a front-yard lamp post. The flower is Clematis x jackmanii, the lighting fixture is classic suburbia.
Reprinted with permission HouseNet, Inc.