Clematis

Fundamental Facts

HARDINESS: Zones 4 to 8
PREFERRED SOIL pH: Near neutral
PREFERRED SOIL TYPE: Moist, fertile, well-drained
PREFERRED LIGHT: Foliage in sun, roots in shade
ATTRIBUTES: Blue, purple, red, pink, yellow, or white flowers; tor trellises, thin supports
SEASON OF INTEREST: Spring through fall
TYPE OF VINE: Deciduous perennial; climbs by clinging with twining tendrils
FAVORITES: C. x jackmanii, 'Henryi', 'Nelly Moser", 'Betty Corning', C. terniflora
QUIRKS: Grows best with foliage in sun and roots in shade
GOOD NEIGHBORS: Azaleas, hydrangeas, bulbs, evergreen shrubs, roses, small trees
WHERE IT GROWS BEST: In sunny sites with moist, organically rich soil
POTENTIAL PROBLEMS: Clematis wilt, a soil-borne disease that enters plants through injuries
RENEWING PLANTS: Vines live many years; prune in summer or winter, depending on variety
CRITTER RESISTANCE: Good
SOURCE: Bedding plants, cuttings
DIMENSIONS: 6-25 ft (1.8-7.6 m); flowers to 8 in (20.3 cm)

Clematis in the Landscape

Boasting some of the most beautiful flowers of any vine, clematis produces abundant blossoms in a range of colors, including blue, purple, red, pink, yellow, and white. The most commonly grown types are the large-flowered types of clematis, which have showy star-shaped flowers up to 8 in (20.3 cm) in diameter.

Clematis vines climb by looping little leaf stalks, or tendrils, around a neighboring branch, wire, stake, trellis, or other thin support.The plants can also be trained to drape over a fence, porch railing, or lamppost. You can even grow clematis in a large container outfitted with a willow-pole tepee. When the plant is not in flower, the leaves make a lovely screen.

Choosing Clematis

With more than 100 clematis in cultivation varying in size, color, and bloom time, choosing one can be confusing. But there are a number of reliable old favorites. For abundant purple flowers from summer to fall, Clematis x jackmanii is a time-tested vine that always performs well. 'Henryi' lights up the garden with snow white flowers ribbed in cream. Other large-flowered classics include the pink-and-white-striped 'Nelly Moser' and the striking, ruby flowered 'Niobe'.

The small, nodding, smoky blue blossoms of 'Betty Corning' work especially well in tight spaces. For early-spring flowers, grow the pink-flowered species C. montana. For fall color and fragrance, try sweet autumn clematis (C. terniflora). Its frothy mass of small white flowers can transform a fence into a breathtaking sight.

Growing Clematis

Clematis like to have their leaves in sun and roots in shade. So select a site where the roots will stay cool and moist, such as behind a shrub, or plan to mulch roots well with organic matter or surround them with a thick groundcover, such as ajuga. In early spring, prepare an 18 in (45.7 cm) square planting hole and amend the soil generously with compost or rotted manure. Set the vine 2 in (5.1 cm) deeper than it grew in its container and be careful not to break any of the brittle stems. Shallow planting or injured stems can invite clematis wilt, which is an incurable, soil-borne fungal disease that causes the vine to die back to the soil each season without blooming. Keep the soil moist until the vine is actively growing. As new stems emerge, tie them loosely to a thin support until the tendrils grab hold. Every spring, mulch vines with 2 in (5.1 cm) of aged manure or compost along with a light dusting of garden lime if your soil is acidic.

Clematis are usually pest free, but new growth may attract sap-sucking insect aphids. Knock them off with a strong spray of water from a hose. Black blister beetles may chew holes in leaves. The larvae are beneficial predators that control grasshoppers. If damage is slight, tolerate adults for the short time they feed. If damage is severe, apply a commercial insecticide registered for use on clematis according to package directions.

Pruning Simplified

Pruning methods for clematis vary depending on the species or cultivar. The goal is to remove old, dead lengths of vine, and to prune to control size. Clematis vines that flower in spring do so on the previous year's growth, and should be pruned in summer, after the flowers fade. Those that bloom in summer on the new growth should be pruned in late winter to within 12 in (30.5 cm) of the ground. Autumn-flowering clematis that is cut back nearly to the ground in winter will come back strong in spring and bloom in the fall.