Wisteria is often confused for a tree, especially when encountered as a solitary, upright specimen. Although it can be shaped to look like a small, flowering tree, this designation is purely horticultural, not botanical. The plant is fundamentally a vine that has been carefully manipulated and trained to maintain an upright, self-supporting form.
Wisteria is Botanically a Vine
The genus Wisteria consists of species classified as lianas—woody, perennial climbing vines common in forest settings. In its natural state, the plant’s long, flexible stems twine tightly around any available support structure, such as tree trunks, pergolas, or arbors. Its vigorous nature allows it to quickly cover large vertical and horizontal spaces, sometimes reaching lengths exceeding 30 feet.
Wisteria stems develop a thick, woody structure over time, giving the mature plant strength. This climbing habit helps the plant seek sunlight and gain height above competing foliage. Without intervention, the plant will never naturally form a self-supporting trunk and canopy like a true tree, remaining instead a dense, multi-stemmed climber.
Training Wisteria into a Standard Form
The “wisteria tree” is formally known as a wisteria standard, requiring several years of focused training and pruning. The process begins by selecting the most vigorous single shoot on a young plant to serve as the main leader, which becomes the future trunk. This leader must be immediately and rigidly staked to a strong, permanent support, such as a metal post, to force a straight vertical position.
As the main stem grows, all side shoots must be removed completely from the ground up to the desired trunk height. Removing this lower foliage directs the plant’s energy into developing a single, thick, woody stem capable of supporting the canopy. Once the leader reaches the target height, its tip is pruned to encourage lateral buds to form the rounded head, or crown, of the standard.
Common Wisteria Species
The two most widely recognized Asian species are Wisteria sinensis (Chinese Wisteria) and Wisteria floribunda (Japanese Wisteria). Both are known for their aggressive growth and fragrant blooms. Chinese wisteria is typically the more vigorous grower, with stems that twine counterclockwise. Japanese wisteria is characterized by longer, pendulous flower clusters, sometimes exceeding 3 feet in length, and its stems twine clockwise.
A less aggressive alternative is the native American species, Wisteria frutescens, which includes the cultivar ‘Amethyst Falls’. This species has a more restrained growth habit, making it easier to manage in smaller gardens. Its flower clusters are shorter, typically 2 to 6 inches long. The native species also tends to be hardier in colder climates and is less likely to become invasive in North American landscapes.
Maintaining the Wisteria Standard
Maintaining the tree-like shape and encouraging prolific flowering demands a rigorous, two-stage annual pruning schedule. The first prune occurs in summer, usually in July or August, after the flowering period has ended. During this time, the long, whippy new shoots that have grown off the canopy are cut back to about five to six leaves.
The second pruning takes place during the dormant season, typically between January and February. The shoots shortened in the summer are cut back further, leaving only two or three buds, or about 1 to 2 inches of growth, on the woody framework. This winter pruning concentrates the plant’s energy into developing short, stubby growths called flower spurs, which produce the spring display. Without this consistent maintenance, the plant’s natural tendency to climb will quickly reassert itself, causing the trained standard to revert to a dense, sprawling vine.