Heavy Pruning of Wisteria

Why Prune

• Wisteria is an aggressively growing vine that often reaches lengths of 25 feet. It has a tendency to destroy roof tiles and siding when given an opportunity, and has been known to clog or pull down gutters. Pruning is advisable for these reasons alone, but the added benefit to pruning wisteria is that it encourages blooms by forcing the plant's energy into building flowers instead of supporting lots of foliage.

Training and Pruning

• Wisteria should be trained into either a tree form or on to a sturdy freestanding trellis. Maintain your chosen shape by pruning the wisteria immediately after blooms are spent and then in late winter before spring growth begins again. Wisteria should only be allowed to develop a single stem and a few leaders. Training your wisteria will help keep it within reach for a lifetime of pruning.

How to Prune

• When pruning wisteria, cut back as much as you dare; it is a hardy vine. In the summer, cut off all new side shoots beyond the seventh leaf when the leaf appears. Go back over the plant in a few weeks and remove any new shoots that have grown from that cut. In winter, cut leaders back by up to one-half, and cut side shoots back to no more than 2 inches in length.

Rejuvenation Pruning

• Occasionally, wisteria is left to its own devices and has to be wrangled back into shape. Prune these vines back dramatically in the winter, when the plant is dormant. Remove all but the main framework of the plant. Take out any excess leaders or crowded sections that are near the main stem. It may take the wisteria two to three years to recover from dramatic pruning, but the plant that reemerges will be stronger and have much more beautiful blooms than the one that was out of control.

Root Pruning

• Root pruning is another method used in combination with vine pruning to encourage blooms and keep the massive growth of wisteria in check. In late fall, use a sharp spade to cut about 18 inches down into the soil, in a circle 4 feet away from the main trunk of the plant. This action severs root growth outside of the 4-foot circle.