STYLE : GARDENS : Cutting Back

Pick a wisteria, any wisteria, and versatility is sure to be its middle name. Though Wisteria floribunda , Wisteria sinensis and Wisteria venusta are known as flowering vines, they can be grown as trees and shrubs. It just depends on how they’re pruned.

In their Northridge garden, Paul Kirk and Mary Finley have pruned a white silky wisteria ( W. venusta ) into an elegant little tree and trained a violet Japanese wisteria ( W. floribunda ) into a canopy for their patio. Both kinds are considered more difficult bloomers than others, but the Kirks say maintenance was a snap. Even easier to grow, says Frank Burkard Jr. at Burkard Nurseries in Pasadena, are the purple Chinese wisteria ( W. sinensis ) and the cultivar ‘Cooke’s Special.’

To begin, buy grafted plants that are bare root at this time of year, or in cans later on, and water and fertilize them often. When the wisterias reach the desired size and shape, decrease water and fertilizer and start pruning to encourage blooms. After a couple of years, the plants will become less thirsty. Too much water, in fact, will prevent pink or white varieties from flowering.

Because wisterias have heavy vines that can crush a trellis or drag gutters from eaves, they must be cut back. Winter is the best time for removing what isn’t wanted and saving the fat flower buds from the summer. In spring and summer, pinch back long twining stems. To shape a tree, keep the trunk free of sprouts and prune more severely. The payoff comes in early spring--a plant that’s dripping with flowers.