HARDINESS: Zones 5 to 9
PREFERRED SOIL pH: Slightly acid
PREFERRED SOIL TYPE: Average
PREFERRED LIGHT: Sun
ATTRIBUTES: Fragrant, drooping flower clusters; tor trellises, arbors
SEASON OF INTEREST: Late spring to early summer
TYPE OF VINE: Hardy woody perennial; climbs by twining around a support
FAVORITES: W. floribunda, W. frutescens, W. sinensis
QUIRKS: Vines on some species twine clockwise, others twine counterclockwise
GOOD NEIGHBORS: Wisteria is best grown as a specimen plant
WHERE IT GROWS BEST: In sun and slightly acid, well-drained soil
POTENTIAL PROBLEMS: Vines can grow out of control or bloom poorly if not pruned regularly
RENEWING PLANTS: Lives for decades; prune back overgrown vines with a saw
CRITTER RESISTANCE: Excellent
SOURCE: Nursery plants
DIMENSIONS: Vines 30 ft (9.1 m) long; clusters 2 ft (0.6m) long
Wisteria in the Landscape
This hardy vine has it all: statuesque woody stems, feathery leaflets, and long clusters of fragrant lilac, pink, or white pea-shaped flowers in spring. Give this heavy vine something substantial to ramble over, such as an 8 ft (2.4 m) tall arbor 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 treelike trunk, a form called a standard.
All in the Family
Japanese wisteria (Wisteria floribunda) 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 2-4 weeks after flowering and then cut side branches back hard, to within 3-6 buds of the main trunk. A second pruning, in late winter, may also be necessary.
American wisteria (W frutescens) 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. It is hardy in Zones 6 to 9.
An excellent alternative for cold climates, Kentucky wisteria (W. macro-stachya) is capable of flowering even in Zone 4. This lilac purple bloomer produces flowers on new growth in early summer and is best pruned in winter.
Chinese wisteria (W. sinensis) is grown from Zones 5 to 8 and 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 cut-rings 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.