Wisteria is a climbing, deciduous vine that produces long, drooping clusters of fragrant flowers. When growing wisteria, it is important to get new plants well established at planting time, but once in the ground, wisteria is easy to grow and very low maintenance. Regular pruning is the primary care task, and it improves flowering and helps maintain a tidy shape. Two of the best tips for encouraging abundant flowering is to limit watering and abstain from applying fertilizers. When it comes to wisteria, too much care can do more harm than good.
When growing wisteria, taking time to select the planting site and prepare the planting hole will contribute to the long-term health and success of the shrub. Wisteria blooms best in full sun, at least six hours a day — but the more the better. A spot that gets good drainage and has a loamy humus-rich soil texture is ideal. Wisteria thrives in slightly acidic soil with a pH level between 6.0 and 7.0. This climbing vine also requires a trellis structure to support its growth.
Once the planting site is determined, a hole 18 to 24 inches (about 45 to 60 cm) wide and with the same depth as the nursery pot should be prepared. The soil from the hole can be mixed with peat moss or manure to create a mixture of two-thirds garden soil and one-third organic soil matter. The additional material improves the soil texture. In alkaline soil, peat moss can increase the acidity of the soil slightly.
One of the primary reasons for growing wisteria is the fragrant flowers, and when a wisteria produces abundant foliage but only a few flower clusters, it can be troubling and frustrating. When growing wisteria, over watering and over fertilizing are the two primary reasons for limited bloom production. Fertilizer, particularly nitrogen rich formulas, and excess water encourage abundant leafy green growth and stem production, but limited blooms. In very poor soils, wisteria may require a light application of fertilizer. Watering should be limited to very hot, dry weather when the leaves begin to wilt.
Regular pruning is important maintenance when growing wisteria. Pruning encourages flower production. This task should be performed in late winter before the plant emerges from dormancy. During the first few years while the vine is getting established, the branches should be cut back by half their length and encouraged to grow into the trellis or structure. Ongoing maintenance pruning for established wisteria should be performed in winter.