Taxonomy and Botany of Chinese Wisteria Plants
Taxonomy classifies Chinese wisteria as Wisteria sinensis. Botanists group it with the deciduous perennials. These vines are in the pea family. In fact, after the flowers fade, they produce velvety seed pods that do look like pea pods.
Plant Traits, Sun and Soil Needs, Planting Zones
All wisterias are stunning bloomers, bearing large, drooping clusters of fragrant flowers, most often bluish-purple, lavender, or mauve in color.
Bloom time is usually in mid-spring to early summer. A few kinds bear white blooms, such as silky wisteria (W. brachybotrys 'Shiro-kapitan'). W. sinensis 'Alba' also bears white flowers. The flowers are rabbit-proof (rabbits tend not to eat any part of the plant, in fact). This plant is deer-resistant, as well.
Chinese wisterias are twining climbers that can wind their way at least 25 feet up a support. Supports must be sturdy, because the mature vines are very heavy.
Some types need full sun to flower, but the Chinese kind is more shade-tolerant. All varieties of these flowering vines want a well-drained soil, made rich by adding compost. Keep the soil evenly moist. These vines can be grown in USDA plant hardiness zones 5-8.
Landscaping Uses, Warning About Growing This Vine
Chinese wisteria plants are vigorous growers. Experts advise against letting them climb up a porch or the side of your house.
Alternate Spelling: "Wistaria" Vines
For research purposes, note that, although the spelling used here is the more popular one, you will also find the spelling "wistaria" vines.
Indeed, the latter spelling is truer to the origin of the word, which comes from the name, "Caspar Wistar," a U.S. anatomist. For instance, Sierra Madre, California holds an annual "Wistaria Festival" every March, during which visitors can view a vine that is 111 years old, weighs approximately 250 tons and bears over 1 million lavender blossoms.
Care: Getting the Vines to Blossom
If you find yourself with the problem of getting the vines to flower (this plant's most common care problem), there are a number of methods you can use to encourage flowering. Briefly, you can begin by changing the fertilizer that you use (a high-phosphorus fertilizer may promote blooming). More importantly, change the way that you do your pruning.
Maybe you have heard the old expression, "Spare the rod and spoil the child"? Well, that approach may now be frowned upon when it comes to child rearing, but it is still good advice when it comes to wisteria care. Tough love (in the form of fearless pruning) may be the answer for getting your stubborn vine to flower.
Japanese and American Types
There are differences between Chinese wisteria vines (Wisteria sinensis) and Japanese wisteria vines (Wisteria floribunda), on the one hand, and American wisteria vines (Wisteria frutescens), on the other.
One problem with the Chinese and Japanese wisteria vines is waiting for a successful outcome with them (that is, their flowering). Waiting for them to finally flower can be just too long a wait for many folks. But some growers do report success in speeding up their flowering through pruning. Chinese wisteria plants respond well to pruning, so there is no need to get fussy with your pruning. Just do it!
An alternate solution to the long wait for flowering, if you can afford it, is to buy an older plant (which will be more expensive) from your nursery. If you shop for Chinese wisteria plants in late spring at garden centers, you can scout for vines already in bloom. Although Chinese wisteria plants tolerate shade, for best blooming, grow them in a sunny area.
Another problem with Japanese and Chinese wisteria vines has already been mentioned: namely, their invasiveness.
You had better be a hands-on gardener if you want to grow Chinese or Japanese wisteria. Be faithful about keeping their growth checked through pruning, or else, as powerful twining vines, they will girdle trees and kill them. In this respect, Chinese wisteria plants pose a danger similar to that of Oriental bittersweet vines.
Fortunately (or unfortunately, depending on how you look at it), you need to prune them anyhow to promote blooming. So you should not be tempted to let the vines grow beyond reasonable bounds. You have two reasons to be motivated to prune.
But here is another answer to the problem of the vines' not blooming. If you live in North America, you may want to buy American wisteria vines, instead. Not only are the latter not invasive in their homeland, but they also bloom faster, too. Japanese and Chinese wisteria plants are more frost-sensitive, as well. American wisteria vines flower in lavender or mauve, and they will sometimes bloom again in September.
Another native alternative for Americans is W. macrostachys ('Blue Moon' is a popular cultivar).