Answer: Two species of wisteria are typically grown in home gardens: Wisteria sinensis or Chinese wisteria, and Wisteria floribunda or Japanese wisteria. The Chinese wisteria is the more popular plant due to its flowering habit. It grows to a height of 25 feet or more and has flower clusters six inches to a foot in length, which open before the foliage has expanded. Individual flowers in the clusters open all at once for a very showy display. Flowers are violet-blue and slightly fragrant. Plants are most showy from early to mid-May in most seasons. There is also a white flowering form of Chinese wisteria, W. sinensis 'Alba,' which is very fragrant. Two cultivars include: 'Black Dragon,' which has double dark purple flowers and 'Plena' with double, rosette-shaped, lilac flowers. Chinese wisteria may bloom within three to four years after planting; however, the juvenile period may be much longer.
In order to bloom well, wisteria require full sun (six or more hours of direct sun per day) and a deep, moderately fertile, moist soil that does not dry out excessively. They will adapt to most soils, though they prefer a neutral to slightly acid soil pH of 6.0-7.0 for best results. Some type of support will be necessary as mature plants can be quite heavy.
Good site preparation will help ensure plant establishment. Begin with a soil test to determine if the soil pH or the phosphorus level need correction. If so, make additions of materials as you are preparing the soil. Prepare soil in an area two to three feet in diameter and 18 to 24 inches deep. Mix into the native soil either peat moss, compost or well rotted manure, one-third by volume, to improve soil aeration and drainage.
Once you've planted your wisteria you'll want to stake it upright until it is 4-5' high. At that time you can attach it to the tree trunk by using fishing line (temporarily until you can twine the vines around the trunk and they stay upright on their own). Each winter, thin the vines and reduce their height to encourage new twining growth.
Best wishes with your wisteria!
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