Does Wisteria Need Full Sun?

Often depicted in a purple cascade falling over walls and stout arches, few plants evoke romance and fantasy as much as wisteria. Two types of Asian wisteria (Wisteria spp.) are most common in the landscape and are vigorous and rampant growers, while a native American species is better behaved. Regardless of type, all wisterias require full sun for best bloom. All young plants only flower sporadically, if at all, during a juvenile period that lasts several years.

All types of wisteria require at least six hours of sunlight daily to look their best; plants look scraggly and thin with less sunlight and flowering also noticeably suffers. Wisteria growing in full sun will have lush, thick vegetation and dense clusters of purple flowers each spring. As a plant found in lowland or streamside areas of its native ranges, wisteria prefers moist, rich soils that do not dry out regularly. Due to its membership in the legume family, it requires no fertilization. All types of wisteria will need a sturdy support, as over time the vines become very thick and heavy.

The Asian species of wisteria most frequently seen at nurseries are usually one of two types: Japanese wisteria (Wisteria floribunda), hardy from U.S. Department of Agriculture plant hardiness zones 5 through 9, and Chinese wisteria (Wisteria sinensis), which grows between USDA zones 6 through 8. Native wisteria (Wisteria frutescens) is also hardy from USDA zones 5 through 9. Japanese wisteria has a number of cultivars with differing flower colors; most bloom before the plant fully leafs out. Chinese and native wisteria have fewer cultivars and flower after the vine’s leaflets have opened. Most types of wisteria are highly fragrant, and flower color includes white, pink, mauve and dark purple in addition to the classic bright amethyst color.

The Asian wisterias are both rapid growers, often growing to between 30 and 50 feet. In reality, both of these plants will continue to grow upwards as long as there is a support to cling to, and can take root where the vine’s nodes touch the ground as well as resprout from portions of root remaining in the ground after removal. Mature vines readily girdle trees, and though homeowners need to put the plant in full sun for best flowering, wisteria will grow in any light condition. Annual pruning of vines is necessary to keep wisteria in check. Due to its invasive nature in many areas, never plant wisteria near a wooded or swampy area where it is more likely to escape cultivation.

American wisteria is also a vigorous grower, but will not continue to climb like its Asian cousins. Overall length is reliably limited to about 30 feet, and it reaches this extent somewhat more slowly than the Asian species. Native wisteria still needs ample light and moist soils for the best appearance. Flower clusters grow only to between 4 and 6 inches, compared to the 9- to 20-inch flower clusters of Asian wisteria types, but native wisteria flowers are usually more vivid in color. As an added bonus, unlike Asian wisteria, native wisteria is a dependable bloomer and often even flowers again sporadically throughout the summer. The foliage serves as food for the larvae of several colorful native butterflies.