Clever tips for choosing and growing wisteria

Wisteria is a hardy vine that has it all: statuesque woody stems, feathery leaflets, and long clusters of fragrant lilac, pink, or white pea-shaped flowers in spring. Here are some clever tips to help you choose and grow wisteria.

• Japanese wisteria (Wisteria floribund.) produces the best show of flowers and is available with blue, pink, or white flowers. Once Japanese wisterias are old enough to bloom, pruning is needed to control their exuberant growth. Wait two to four weeks after flowering and then cut side branches back hard, to within three to six buds of the main trunk. A second pruning, in late winter, may also be necessary. If flowering is poor, give this winter pruning by shortening new shoots back to two to three buds.
• American wisteria (W. frutescen.) is less vigorous than Japanese wisteria and better suited to small gardens. Its cultivar 'Magnifica' has blue flowers; 'Nivea' has white flowers. Because this species flowers on new wood, prune established vines heavily in winter. The show begins in midspring and is followed by a growth spurt and a second flush of bloom in early summer, and possibly a third in late summer.
• Kentucky wisteria (W. macro stachy. [Z7]), an excellent alternative to American wisteria, produces lilac purple flowers on new growth in early summer and is best pruned in winter.
• Chinese wisteria (W. sinensi.) is a popular choice for gardens along the West Coast. It has shorter flower clusters than Japanese wisteria, and rather than opening gradually, the clusters pop open all at once, often with an explosion of fragrance. It blooms in late spring and can repeat in summer.

• Begin with wisteria grown from cuttings or grafted plants, which will flower in a couple of years.
• Plant in spring in deeply dug, well-drained soil enriched with organic matter.
• Beginning a year after planting, fertilize in spring with high-phosphorus fertilizer, such as a 5-10-5 formula.
• Wisterias are pest and disease free, and need little care other than irrigating as needed to keep the soil moist while vines are flowering.
• If your wisteria refuses to bloom and it's still small enough to handle, digging it up and replanting it can sometimes trigger the vine to flower.

Give this heavy vine something substantial to ramble over, such as a 2.5- metre-tall (eight-foot-tall) arbour held aloft on stout posts. Or let it scramble into large trees, as it does in the wild. Where space is limited, you can still enjoy wisteria by pruning it into an umbrella shape on a single tree-like trunk, a form called a standard. Keep these tips in mind and add wisteria to your outdoor space.