Two tamer wisteria vines to try
Wisteria vines, for the most part, are not for the weak gardener. Most of the plants sold are Japanese wisteria (Flowering wisteria) and Chinese wisteria (Wisteria sinensis) – thuggish Asian imports that often escape managed parks. They climb the tallest trees and utility poles, spread at the speed of light, and their muscular, coiled legs can bend iron, crush a tree, or choke small trees to death. Vines sprout from the ground from thick, aggressive roots, forming thickets that choke out other plants. They both invaded the south, crawling their way along forest edges and roadsides. However, we grow it for its hanging chains of beautiful, fragrant spring flowers.
There is a smarter option for those who can’t resist their lilacs. There are two beautiful and gentle species of wisteria that are native to the United States. Both are deer resistant and will attract hummingbirds and butterflies to the garden.
wisteria kentucky (Large wisteria) is located in the south-central United States. It’s more cold-tolerant than the Asian species and is suitable for USDA zones 4 through 9. It also blooms later than it does — in May or June, depending on where you live — so the flowers are rarely exposed to late frosts. Fragrant, lavender-blue racemes up to 12 inches long cascade from its stems. The ‘Blue Moon’ selection (pictured above) blooms up to three times a year once established, with spring blooms being the heaviest. It can grow up to 25 feet tall very quickly, so don’t think you can plant it and then forget about it. Annual pruning keeps it under control.
American wisteria (Wisteria fruit) Another citizen worth watching. Think of it as a smaller, slower-growing version of Kentucky wisteria. They bloom at about the same time, but their flowers look completely different. Instead of being chain-shaped, the six-inch-long racemes are clustered, looking like purple corn kernels cut in half. It’s not quite as sweet-smelling as Kentucky wisteria. ‘Amethyst Falls,’ a popular choice, repeats blooms like ‘Blue Moon,’ but it is a less aggressive plant with thinner stems and will not damage wooden arbors or trellises. You can even grow it in a container. While it can eventually grow to 20 feet if left unchecked, ‘Amethyst Falls’ grows at about one-third the pace of the Asian species and needs little pruning. It is suitable for USDA zones 5 through 9.
For best blooms, plant either vine in full sun in moderately fertile, well-drained soil. They like moist soil but are drought tolerant once established. They will do their best if you give them some water when the weather is hot and dry.
Vines usually flower in the second or third year after planting. At some point, you will likely need to prune the vines to maintain the size and shape you want. This wisteria blooms on new wood, so do not prune new growth until after spring flowering (better yet, prune in winter before growth appears). Both wisteria set seeds, so remove the bean-like seed pods before they mature if you don’t want seedlings popping up around your garden.
Remove invasive wisteria
You’ve been warned not to plant Chinese or Japanese wisteria, but it may be too late. Or perhaps a neighbor’s ill-fated choice brought the plague to your garden. Removing this deep-rooted plant requires persistence. Start by cutting all the vines down to the base. You can also coat the end of each log with an herbicide such as Roundup (do this within five minutes of making each cut, otherwise the herbicide will not be absorbed). No matter what, expect more shoots to appear from the longer roots, sometimes over several seasons. But don’t despair: As long as you keep removing growth to starve the plant, it will eventually die, making room for other plants that will play well in the garden.