Characteristics of Wisteria

Wisteria flower clusters grow up to 12 to 18 inches long.

Native to Asia and the United States, wisterias add showy, colorful blossoms to yards or landscapes. These perennial vines received their name from University of Pennsylvania professor Caspar Wistar (1761-1818). Wisterias grow in U.S. Department of Agriculture Hardiness Zones 5 through 9. Exotic species, such as Chinese wisteria (Wisteria sinensis) can become invasive and overtake naturally occurring vegetation. Wisteria frutescens, which is native to the United States, is a non-invasive alternative, according to the North Carolina Forest Service.

Flowers

In the spring, wisteria produce large drooping flower clusters up to 12 to 18 inches long. Chinese wisteria (Wisteria sinensis) has purplish blue, pea-like flowers that bloom all at once in the spring. Wisteria sinensis "Alba" produces exceptionally fragrant white flowers. Other cultivars, such as "Black Dragon," produce double flowers. Japanese wisteria (Wisteria floribunda) blooms gradually, beginning at the base of the flower clusters. This type of wisteria offers many colors, including pale rose and reddish purple.

Stems and Foliage

The stems usually grow in clumps but will train to grow as a single thick trunk. Mature plants develop twisted woody stems up to 10 inches thick. Chinese wisteria stems wind counterclockwise around a structure, and Japanese wisteria stems wind clockwise, according to the North Carolina Forest Service. Wisteria vines produce deciduous leaves that expand after the flowers begin to bloom. The ovate, pinnately compound leaves grow alternately along the vine and turn yellow in the fall. Leaves measure up to 2 to 4 inches long.

Fruit

In the summer, wisteria plants produce flat green pods that contain seeds. The hard pod covers have a velvety texture. When the 4- to 6-inch-long pods dry and turn brown, the seeds are ready for harvest. If you propagate wisteria from seeds, be prepared to wait at least eight years for flowers to bloom. Wisteria seeds are poisonous and not edible.

Height

Wisteria vines spread quickly, and can climb 25 feet or more on trellises and other supports. These vigorous growers can damage trees and buildings, and need regular pruning. You can control the size of a wisteria by training it to grow as an upright, single-stemmed tree. The University of Illinois Extension recommends staking the stem and allowing it to grow to a suitable height for your environment. After you prune back the stem, side branches will grow.

References

• North Carolina Forest Service: Wisteria floribunda (Japanese wisteria), Wisteria sinensis (Chinese wisteria); Cherri Smith; 2008
• University of Illinois Extension: Wisteria; Jennifer Schultz Nelson; April 2010
• Ohio State University Extension: Growing Wisteria; Jane C. Martin
• University of Florida Extension: Wisteria Sinensis Chinese Wisteria; Edward F. Gilman; May 2007
• University of Arkansas Cooperative Extension Service: Vines -- Wisteria; Janet Carson
• New Mexico State University Extension: Wisteria Seed Planting and Peach Tree Seedlings; Dr. Curtis Smith; May 2009