Clematis

(Ranunculaceae - Buttercup Family)

Form

• small, semi-woody, ornamental vine
• maturing at 5' to 20' in length, depending upon type
• twining vine growth habit (climbing by petiole twining much more than by stem twining)
• rapid growth rate

Culture

• full sun to partial shade; often best placed in partial sun, especially in more Southern climates
• prefers moist, well-drained, moderately fertile soils that have a cool (mulched) root zone, but is rather adaptable to average soils and soils of various pH
• propagated by rooted stem cuttings, seed, or crown division in the Spring
• Buttercup Family, with several disease and pest problems, including stem rot, clematis borer, and root-knot nematodes
• abundantly available in containers, with many species, hybrids, and cultivars
• roots must be kept cool in a well-drained soil for establishment and optimum growth (mix organic matter into the soil upon transplanting, then mulch)
• in Northern climates, most Clematis need to be pruned rather severely by late March (they emerge early) due to Winter dieback, but in both Northern and Southern climates, annual thinning and pruning should be done to promote vigor, large floral size, and to control rampant growth
• with few exceptions, Clematis needs some type of continuous, thin, lattice-type support (such as chain-link fencing, heavy gauge chicken wire, thin wood lattice, or snow fencing [toned down by brown paint, if it is orange]) around which the petioles can twine and/or the stems can run through, if it is to effectively climb a structure; smooth or flat structures such as porch columns and mailbox posts do not provide holdfasts (by themselves) to support Clematis
• most Clematis can be pruned hard every late Autumn or late Winter, since most Clematis flower on new growth; however, a few species or cultivars flower exclusively on old wood (that is, from floral buds developed on the previous year's growth); unfortunately, the gardener must know on an individual basis the few which cannot be pruned before bloom without sacrificing the current year's flowers, or possibly delaying them to a late Summer or early Autumn bloom period

Foliage

• medium green to dark green
• opposite leaves may be simple, ternate, or compound, depending upon type and position on the stem, with their 1" to 2" long twining petioles (which are analagous to twining tendrils on other types of vines) being the main method by which Clematis climbs and anchors itself to a supportive structure
• ovate leaflets, with acute to acuminate apices and palmate veination
• fall color green to chartreuse and ornamentally ineffective

Flowers

• many floral choices of size and color, depending upon type and cultivar
• sepals are usually white, yellow, pink, red, violet, purple, or blue, or sometimes bicolored or with bars (a stripe along the central axis of each sepal)
• either solitary or with several flowers per inflorescence
• individual flowers have sepals (they are the showy portions, instead of petals) that total from 0.5" to 7" across, depending upon type and cultural conditions
• bloom period of late May through mid-October for all types of Clematis, with Spring, Summer, or Autumn flowering periods for individual cultivars; many late Spring and early Summer flowering cultivars will sporadically rebloom in late Summer and early Autumn
• prominent central styles may also contribute to the floral "eye" quality, especially if they are of a different color

Fruits

• fruits are semi-showy on some cultivars, due to their persistent curving styles that are attached to the central cluster of hidden seeds

Twigs

• stems may be ribbed or grooved, becoming slightly exfoliating and semi-woody with age
• on very young plants, the stem is fragile at the juncture of the roots and stem, being subject to complete separation or bending during transplant handling; on established plants that have be rejuvenated by hard pruning, new stems are also fragile at the junctures with the old wood, until they develop a woody consistency during the growing season

Trunk

• not applicable

ID Summary

• multi-stemmed vine that climbs primarily on supportive structures by its twining leaf petioles, having ovate leaflets on the generally compound leaves, and having extremely showy flowers that bloom in Summer, often from 4" to 6" wide, in a broad range of mostly solid cooler colors, with the sepals as the primary attractive portion of the flower, sometimes in combination with the central styles

USAGE

Function

• structural cover for trellises, fences, arbors, mailboxes, rock walls, columns, or other upright structures; some gardeners like to train a Clematis up a shrub or tree to create an unusual "pseudo-flowering" of the supportive plant

Texture

• medium texture in foliage and when bare (many are bold- or fine-textured when in flower)
• open, average, or thick density in foliage and when bare (variable due to maturity, as well as how close or far apart the stems are to each other as the vine climbs a structure)

Assets

• very showy prolonged flowering
• many Spring- or early Summer-flowering types have sporadic flowering later in the season

Liabilities

• many Clematis are very slow to establish
• stem rot or stem borers may destroy individual stems back to the base of the vine during Summer, leaving behind a "trail" of dead foliage clinging to the dead stem that weaves throughout the living stems
• dead leaves often remain on the plant throughout Winter, if autumn pruning is not performed
• Winter dieback or overall vigorous growth often necessitates late Autumn or late Winter pruning
• vines can get moderately out of control once established

Habitat

• zones 4 to 8 for most species and hybrids
• native to various parts of the world, depending upon species

SELECTIONS

Alternates

• other perennial flowering vines (Campsis radicans, Hydrangea anomala petiolaris, Wisteria floribunda, etc.)

Variants

• many species and many more hybrids (sometimes organized into hybrid groups) exist, primarily selected for floral color(s), bloom period, and/or mature plant size; several of the most popular are listed below:
  • Clematis 'Ernest Markham' - light red-violet 4" wide flowers, flowering on new wood in June
  • Clematis 'Henryi' - white 5" wide flowers with purple stamens, flowering on old wood in June and later in the season on new growth
  • Clematis x jackmanii - deep purple-blue 5" wide flowers with subtle yellow stamens cover this vigorous old-fashioned hybrid in June, quite possibly the standard by which all other Clematis are judged
  • Clematis 'Lady Betty Balfour' - blue-violet 4" wide flowers, flowering on new wood in July
  • Clematis maximowicziana (previously classified as Clematis paniculata) - Sweet Autumn Clematis - creamy white, 0.5" wide, four-sepaled, mildly fragrant miniature flowers cover this quick-establishing and vigorous species in September; foliage is semi-evergreen to evergreen; vines may reach 30' or more in length at maturity, but can be rejuvenated and kept under control by pruning back to the base in late Winter or early Spring
  • Clematis 'Nelly Moser' - pale mauve 5" wide flowers with a deep pink bar in the center of each sepal, flowering on old wood in June and later in the season on new growth
  • Clematis 'Niobe' - velvety dark crimson-violet 5" wide flowers with red stamens, flowering on new wood in June
  • Clematis tangutica - Golden Clematis - golden-yellow 2" long flowers hang like bells from the stems in July, with the sepals partially folded together

Translation

• Clematis translates as "vine branch".
• many of the cultivars are named after people.

Purpose

• Clematis is probably the most popular of the perennial flowering vines.

Summary

• Clematis is a genus that, although it contains perennials and shrubs, is known for its numerous species, varieties, groups, hybrids, and cultivars of flowering vines, many of which have an abundance of large, colorful, showy flowers that bloom for several weeks in Summer.