Wisteria

Plant Characteristics
Habit		vine-climber
Lifespan:	⌛	perennial
Bloom:	❀	early spring

Cultivation

Features:	✓	deciduous, flowers, fragrance

Scientific Names
Fabaceae >	Wisteria >				Nutt. >

Wisteria (also spelled Wistaria) is a genus of about ten species of woody climbing vines native to the eastern United States and the East Asian states of China, Korea, and Japan. Aquarists refer to the species Hygrophila difformis, in the genus Hygrophila, as water Wisteria.

Wisteria vines climb by twining their stems either clockwise or counter-clockwise round any available support. They can climb as high as 20 m above ground and spread out 10 m laterally. The world's largest known Wisteria vine is located in Sierra Madre, California, measuring more than an acre in size and weighing 250 tons.

The leaves are alternate, 15 to 35 cm long, pinnate, with 9 to 19 leaflets. The flowers are produced in pendulous racemes 10 to 80 cm long, similar to those of the genus Laburnum, but are purple, violet, pink or white, not yellow. Flowering is in the spring (just before or as the leaves open) in some Asian species, and in mid to late summer in the American species and W. japonica. The flowers of some species are fragrant, most notably Chinese Wisteria. The seeds are produced in pods similar to those of laburnum, and, like that genus, are poisonous.

Read about Wisteria in the Standard Cyclopedia of Horticulture
Wisteria (named for Caspar Wistar, 1761-1818, Professor of Anatomy in the University of Pennsylvania, but spelled Wisteria by Nuttall, author of the genus, the spelling Wistaria being a later adaptation). Leguminosae. Wisteria. Wistaria. Attractive large twiners with pea-shaped flowers, planted for covering porches, arbors, and buildings; the noblest of the woody vines for temperate regions. Stout vines, often attaining great age and with woody trunks reaching several inches in diam.: lvs. odd-pinnate, alternate, with 9-13 lfts.: fls. blue, lilac, purplish, or white, in long drooping racemes, in late spring and early summer; calyx bell-shaped, somewhat 2-lipped from the 3 lower teeth being longer than the 2 upper ones; standard large, reflexed, narrowed below and typically with 2 callosities or appendages at base; wings falcate, auricled at base; keel obtuse, scythe-shaped; stamens diadelphous: fr. an elongated 2- valved torulose pod.—The recognized species are 2 in the eastern U. S., and 4 in eastern Asia. Under the American Code, the genus takes the name Kraunhia; the name Bradleia has also been applied. The so-called "evergreen wisteria" is Millettia megasperma, described on page 2706, Vol. V. The species of Wisteria are so much confused in domestication that few portraits of them are cited in the following account. Wisterias will live in rather dry and sandy soil, but they prefer a deep and rich earth. The roots are long and few and go down deep, making few fibers. They resemble licorice root. They are hard to transplant, unless they have been pot-grown for the purpose or frequently transplanted in the nursery row. Unless manured heavily when transplanted, they are very slow in starting into vigorous growth. The most satisfactory method of propagation for the amateur is layering in summer; the following year the layers may be detached. Seeds grow readily, but do not reproduce the horticultural forms; such forms may be grafted on seedlings of W. frutescens or other available stock, the union being made at the crown; sometimes root-grafting is employed. Cuttings of roots, an inch or two long, are also frequently used. Cuttings of ripened wood may be struck under glass. Those who wish to give a young wisteria an extra-good start may sink a bottomless tub in the ground and fill it with good soil. If a wisteria is to be trained to a tree, choose an old tree, if possible, which is past the height of its vigor; but good results are to be expected only when sunlight and opportunity are ample, and these can rarely be secured under a living tree-head. The Japanese wisteria (W. floribunda) is one of the best and commonest of hardy climbers. It has pale green pinnate foliage and bears profusely of dense drooping clusters of purplish pea-shaped flowers. The clusters are about a foot long. This is the commonest and best form. The variations furnish the connoisseur with variety in habit, color, and season of bloom, but they are not as prolific, and doubling adds nothing to the beauty of the flowers. Moreover, the double flowers decay quickly in wet weather. The wisterias bloom in May and usually give a smaller crop of flowers in August or September. The spring crop is borne on spurs, while the autumn crop is borne on terminal shoots of the season. There are several ideas about training a wisteria. A good way is to let it alone. This produces rugged twisted and picturesque branches and gives a certain oriental effect, but it is not the best method for covering a wall-space solidly or for making the best display of bloom. To cover a wall completely it is necessary to keep the leaders taut and to train outside branches wherever they are needed. If quantity of bloom is the first consideration, the vines should be pruned back every year to spurs, a common method in Japan. The low one-storied Japanese building will have a wisteria so trained that the vine follows the eaves all around the house. The foliage is all above, and the yard-long clusters of purple blossoms depend therefrom in solid unbroken linear masses two or three ranks deep. When trained as a standard, the wisteria requires much care. "When young plants of wisteria are cut back to a height of 6 or 8 feet and pruned in for some years, the stem will stiffen until it is able to stand alone, and the top will spread out into a broad head." The above text is from the Standard Cyclopedia of Horticulture. It may be out of date, but still contains valuable and interesting information which can be incorporated into the remainder of the article. Click on "Collapse" in the header to hide this text.

Cultivation

Wisteria, especially Wisteria sinensis, is very hardy and fast-growing. It is considered an invasive species in certain areas. It can grow in fairly poor-quality soils, but prefers fertile, moist, well-drained ones. It thrives in full sun to partial shade.

Wisteria can be propagated via hardwood cutting, softwood cuttings, or seed. However, seeded specimens can take decades to bloom; for that reason, gardeners usually grow plants that have been started from rooted cuttings or grafted cultivars known to flower well. Another reason for failure to bloom can be excessive fertilizer (particularly nitrogen). Wisteria has nitrogen fixing capability (provided by Rhizobia bacteria in root nodules), and thus mature plants may benefit from added potassium and phosphate, but not nitrogen. Finally, wisteria can be reluctant to bloom because it has not reached maturity. Maturation may require only a few years, as in Kentucky Wisteria, or nearly twenty, as in Chinese Wisteria. Maturation can be forced by physically abusing the main trunk, root pruning, or drought stress.

Wisteria can grow into a mound when unsupported, but is at its best when allowed to clamber up a tree, pergola, wall, or other supporting structure. Whatever the case, the support must be very sturdy, because old wisteria can grow into immensely strong and heavy wrist-thick trunks and stems. These will certainly rend latticework, crush thin wooden posts, and can even strangle large trees. Wisteria allowed to grow on houses can cause damage to gutters, downspouts, and similar structures. Its pendulous racemes are best viewed from below.

Wisteria flowers develop in buds near the base of the previous year's growth, so pruning back side shoots to the basal few buds in early spring can enhance the visibility of the flowers. If it is desired to control the size of the plant, the side shoots can be shortened to between 20 and 40 cm long in mid summer, and back to 10 to 20 cm in the fall. The flowers of some varieties are edible, and can even be used to make wine. Others are said to be toxic. Careful identification by an expert is strongly recommended before consuming this or any wild plant.

Propagation

Pests and diseases

Species

Wisteria brachybotrys
Wisteria floribunda - Japanese Wisteria
Wisteria frutescens - American Wisteria
Wisteria japonica
Wisteria macrostachya - Kentucky Wisteria
Wisteria sinensis - Chinese Wisteria
Wisteria venusta - Silky Wisteria
Wisteria villosa

Non-Wisteria species:

Hygrophila difformis - Water Wisteria

Gallery

Wisteria against ruined house
Great wisteria - Aged approx. 140 years and branch spreads to size of approx. 1,990 Square metre
Wisteria sinensis trained to grow up and along a building wall.
Wisteria floribunda
Wisteria floribunda
Wisteria floribunda
Ozark Wisteria
Ozark Wisteria
Wisteria in flower climbing up a spruce tree
Wisteria Japonica
The oldest Wisteria in Britain at Fuller's Brewery Chiswick
Wisteria frutescens
Wisteria frutescens
Season-impression animation of a free standing Wisteria sinensis at the Tsubo-en Zen garden