The Gardener Within: Joe Lamp'l, a master gardener and author, offers planting tips for clematis.
When folks think of clematis, most imagine the big pinwheel flowers of hybrids like Jackman. These bold, deep-purple summer beauties are one of the most popular and widely planted clematis on the market, with dozens of cultivars. But there are countless other garden-worthy candidates.
Some sport dense clusters of little, starry blossoms, others show off bell-shaped or freckled flowers. One even features a rough-textured, yellow bloom that looks like a freshly peeled orange. With a good combination of vines, clematis can be enjoyed from spring to well beyond frost.
Here are some favorite seasonal blooming species:
• Spring bloomers. The early bloomers are tough vines that are smothered with flowers in April and May. Indian virgin’s bower is hardy to Zone 6, and Alpine virgin’s bower to Zone 5, and feature apple-blossomlike flowers in white and pinks. C. armandii has vanilla-scented white flowers and is evergreen in Zone 7 and above.
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• Summer bloomers. These are the popular, large-flowered cultivars that bloom in June and July. Properly pruned, some varieties, like “Lord Nevill,” Zone 4, can have a second flush of flowers in September and October. Lord Nevill is great in containers because of its compact habit and tolerance for part shade. “Belle of Woking” produces silver-mauve double flowers. It’s hardy to Zone 5.
• Early fall bloomers. These clematis come into their own when most of the garden has stopped blooming in the summer heat. Sweet autumn clematis, Zone 6, shows a mass of white flowers with a spicy scent in September and October. Orange-peel clematis, Zone 6, produces bumpy, somewhat ragged flowers that look like a peeled orange. Fall bloomers also create silky, shimmering tasseled seed heads that provide interest long after the flowers fade.
There’s an old saying that instructs you to grow clematis “with its head in the sun and its feet in the shade.” Plant it where it will receive six hours of sun a day, with the base shaded by a fence, shrubs or lower-growing perennials. Dig the hole at least 18 inches deep and wide, allowing the two lowest sets of buds to be buried when you backfill with soil. This is an insurance policy for young plants. If it suffers a freeze, insect damage or gets broken, the vine can grow again from the protected underground leaf buds.
Cover the base with a 2-inch-thick layer of mulch and water frequently and deeply, especially the first summer while the plant in getting established. In northern climates, apply a balanced 10-10-10 granular fertilizer to the soil in spring, followed in summer by liquid fish emulsion according to package directions. Stop feeding completely in September so the plant can rest during winter dormancy.
Be patient with young plants; clematis takes a while to establish and start flowering: “First year sleeps, second year creeps and third year leaps,” the saying goes.
Clematis climbs by wrapping flat tendrils around objects, so they need support made from screening, nylon netting or wooden lath. Build trellises at least a foot from walls and structures to promote air circulation and prevent fungal infections.
For small-flowered spring bloomers, prune immediately after the flowers fade, but only to control the size of the vine and remove dead or damaged wood. Cut back to the second pair of leaf buds on a branch. For large-flowered summer bloomers, prune twice a season to encourage fall flowering. Cut one side of the plant back to pairs of leaf buds in the desired shape in January. Two months later, cut the other side. Remove dead and damaged wood. The vines will twine together and distribute flowers throughout the plant.
Small-flowered, late-summer bloomers blossom on new shoots, so you can prune as much as needed to control size in late February. Make pruning cuts just above a set of green leaf buds, and remove all dead wood.
Clematis makes a terrific companion plant, extending the season for spring flowers and adding color to hedges, deciduous trees and plain green plants like evergreen juniper and spruce. Use their fast-growing foliage to cover homely objects or draw attention to special garden features like gates or pergolas.
Joe Lamp’l, host of “Growing a Greener World” on PBS, is a master gardener and author. For more information visit www.joegardener.com.
Some plant may be considered noxious weeds in your area. If you’re not sure what plants may be invasive in your area, check with your local garden, horticultural center or noxious weed control board.