Wisteria, one of the most beautiful plants on earth, can last for 50 years and more. It can also, and has a reputation for doing so, drive you and your heirs nuts.
To begin with, after you plant wisteria, years and years may go by before you see a first bloom.
Also, unless you’re prepared to watch closely and prune ruthlessly, wisteria vines will take over whatever they cling to. If it’s the side of your house or a porch railing, beware. In some settings, wisteria gets treated as an environmental pest requiring rigorous measures of eradication.
If you’re lucky to own a fieldstone fence, that’s a good place to grow wisteria because you don’t have to worry about it getting into woodwork.
All this aside, a gardener with patience, determination and the skills to erect trellises, arbors or pergolas, can get to enjoy one of springtime’s loveliest sights — vines bearing large, hanging flower clusters that come in white and shades of pink, lilac blue and purple, and smell sweet. Lengths of rust-free copper or aluminum wire attached four inches from the wall make good supports.
I bought a 5-foot-tall wisteria this spring planning to raise it as a small tree near a shed. I chose the site because I wanted to try a free-standing wisteria variety, needing no supports, that would still serve as an ornamental plant to hide the shed. The plant was healthy, not to say bursting with potential energy, and its sunny and sheltered location looked good.
After planting, I noticed that some of the tendrils were really too close to the side of the shed. That prompted a vision of tentacles reaching out and strangling the shed. So I dug it up and planted it farther away.
Growing it as a tree doesn’t mean I won’t have work to train it. The plant came already staked upright and with its top cut off. I must now allow side shoots to develop on the upper part but remove any lower down. Then I have to follow strict regimes of winter and summer pruning.
At the end of all this I hope the tree will live up to the nursery tag on my plant which promises 8- to 12-inch grapelike bunches of white flowers in mid-May.
I won’t be holding my breath for it to bloom next spring. That would be phenomenally fast for it to happen, and I’m resigned to waiting longer. Many reasons are given for delay or failure to bloom. To begin with, wisterias have a longer than average period of acclimatization. Plants that have been grown from seed may take as long as 15 years. Grafts or plants grown from cuttings will usually bloom earlier.
Also, the site may not be sunny enough. Or, the nursery where you bought it may have given it too much nitrogen fertilizer, stimulating leafy growth but not blooms. Poor pruning is another factor. A harsh winter may have injured or killed flower buds.
My daughter, who gardens in Maryland, says the only way she can get her wisteria to flower is to dig a trench near the roots each spring and fertilize with phosphate.
Clearly, there are a lot of “ifs” to wisteria, but the plant is so good-looking that many gardeners are tempted at one time or another to try their luck with it.
Two renowned kinds for the garden are Japanese (Wisteria floribunda) and Chinese (Wisteria sinensis). There is also a native American (Wisteria frutescens) once known as Kentucky kidney bean.
For what it may be worth, vines of the Japanese variety twine clockwise around their host while the Chinese twine counterclockwise. Both varieties can reach heights of 25 feet and more. The Chinese flowers bloom before the foliage expands while the Japanese bloom and leaf out simultaneously.
A Chinese cultivar named Alba produces fragrant white bloom. Two other featured Chinese cultivars are Black Dragon, with dark purple flowers, and Plena with rosette-shaped lilac flowers. A lovely Japanese cultivar is Longissima Alba with clusters of white flowers 15 inches long. Pale rose Rosea has purple tips and grows 18 inches long.
Wisteria was named in honor of Caspar Wistar, a distinguished 18th century botanist who was a professor at the University of Pennsylvania, president of the Philosophical Society and a friend of Thomas Jefferson. The plant had flourished earlier in England.