In spring, wisteria’s showy flowers cascade from twining vines, which can grow to the size of a small tree trunk. This plant needs support, and is often grown on arbors or pergolas. Wisteria can grow up a wall very nicely, as well. Although there are lots of cultivars available, most are produced from two species -- Wisteria sinensis, or Chinese Wisteria, and Wisteria floribunda, or Japanese Wisteria -- and grow in USDA Hardiness Zones 4 through 9, depending on the cultivar.
1. Where to Plant
A wisteria’s heavy frame will require significant support. It’s a good idea to choose a sturdy wall, such as brick or rock, otherwise the plant's weight will overcome its base. Also choose an area to commit to the wisteria – a plant you don’t want to try to transplant later. In addition, pick an area that will allow you to easily prune the plant, as wisterias require regular pruning to encourage flowering and keep vines under control.
2. Establishing Vines
A little handy work is involved when training or establishing vines on a wall. Begin by screwing a row of 6- to 8-inch L-brackets to a wall. The first row of brackets should travel vertically up the center of the wall while other rows run horizontally with brackets in horizontal rows spaced 2 to 3 feet apart. Attach the very top brackets 3 feet below any eaves, tree branches, or other structures to keep vines from spreading. Run galvanized wire between the brackets and attach young vines to the wire with string. The vines will twirl around the wire as they grow, and the 6- to 8-inch L-brackets will establish some space between the plant and the wall for air circulation and growth.
Throughout the first year of growth, water your wisteria regularly to encourage healthy root establishment. Once roots develop and establish, your plant should only need the occasional watering during dry spells. Growers can apply a high potash (or potassium) feed in the spring to encourage flower production. Just don’t overdo it on the potash, as it could possibly cause more foliage than flowers.
Wisteria needs to be pruned twice a year. Prune in late winter to prepare the flowering spurs for spring. Prune again in mid-summer to prevent long, whippy shoots from heading astray and finding a path off the wall. In addition, this will encourage the shoots to flower instead of vine. During the first couple of years, the goal of pruning is to create a framework of permanent vines that will establish the plant's "home" on your wall. Select and tie specific main shoots to the support wires and cut away any unwanted growth. After a couple of years, these vines will build up as the framework, or skeleton, of your wisteria. After the framework’s development, you can prune to create flowering spurs and to keep the plant within its designated home.