Wisteria

Wisteria frutescens (American wisteria, incl. Kentucky wisteria, var. macrostachya); W. sinensis (Chinese) and W. floribunda (Japanese) · Pea family (Fabaceae)

At a glance
Hardiness zones	3 to 9
Sun	full sun
Water	moderate
Life cycle	perennial
Frost	Hardy: takes frost

About Wisteria

Wisteria is a long-lived woody vine with hanging clusters of pea-like flowers in purple, lavender, blue, pink or white. Chinese and Japanese wisteria are invasive in much of the East and South: they climb over trees, can break limbs and form dense thickets, and Connecticut now prohibits planting or selling them (NC State; Clemson; Connecticut invasive plant list). Native American and Kentucky wisteria are the better-behaved choice, with shorter clusters that open after the leaves. Every wisteria grows heavy and needs a very sturdy support.

American wisteria is hardy in zones 5-9, Japanese in 4-9 and Chinese in 5-8 (NC State); Kentucky wisteria such as 'Blue Moon' is hardy to about zone 3 (USU). Chinese and Japanese wisteria are invasive: prohibited in Connecticut and listed in Florida, Maryland, Virginia and New York.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Plant a grafted or cutting-grown plant of a named variety: seedlings can take up to 15 years to bloom (USU). Build the support first, with 6x6 posts or steel, because wisteria hates being moved and can crush lattice and damage gutters and siding (USU, NC State). Keep the soil moist while it blooms and when next year's buds form in August and September (USU).

Soil

Moist, well-drained, moderately fertile soil that's slightly acidic; high-pH soil can cause yellow leaves from iron chlorosis (NC State, USU).

Moderately fertile, well-drained, slightly acidic soil; test first, since high pH can cause iron chlorosis (NC State, USU).

Feeding

Early spring, only if a soil test shows a need: a light feeding low in nitrogen; phosphorus only if the soil lacks it. NC State notes an early-spring feeding can help flowering but overfeeding prevents it; USU says added nitrogen usually isn't needed.

Too much nitrogen gives leafy vines and few flowers (USU, NC State).

Harvest

Blooms in spring: Asian wisterias in April-May as the leaves open, American wisteria in April-May after leaf-out, and Kentucky wisteria around June with some later rebloom (NC State, Illinois Extension). Prune twice a year: right after bloom cut the long new shoots back by about half, and in late winter before leaf-out shorten the side shoots to 6-12 inches (USU).

Varieties (19)

Variety	Type	Notes
Alba	American wisteria (W. frutescens), native	White, mildly fragrant flowers.
Amethyst Falls	American wisteria (W. frutescens), native	Lightly fragrant lavender-purple flowers in short clusters; the most common American wisteria in the trade.
Dam B	American wisteria (W. frutescens), native	A Texas selection with bright blue flowers.
Magnifica	American wisteria (W. frutescens), native	Denser and showier, with deeper lavender-purple flowers in often slightly larger clusters.
Nivea	American wisteria (W. frutescens), native	Snow-white flowers on shorter clusters.
Swantly Purple	American wisteria (W. frutescens), native	Fragrant, deep purple-violet flowers.
Chinese wisteria (W. sinensis)	Chinese wisteria (W. sinensis), invasive	Mildly fragrant blue-violet flowers in 6-12 inch clusters that open almost all at once before the leaves; fuzzy pods; very vigorous.
Jako	Chinese wisteria (W. sinensis), invasive	White flowers.
Prolific	Chinese wisteria (W. sinensis), invasive	Starts flowering at a younger age than most.
Carnea (Kuchibeni)	Japanese wisteria (W. floribunda), invasive	White flowers with pink tips.
Issai	Japanese wisteria (W. floribunda), invasive	Violet to blue-violet flowers in 12-inch clusters.
Japanese wisteria (W. floribunda)	Japanese wisteria (W. floribunda), invasive	Very fragrant pink to purple flowers in 12-18 inch clusters that open from the base outward as the leaves emerge; longer bloom period than Chinese wisteria.
Longissima Alba	Japanese wisteria (W. floribunda), invasive	Very fragrant white flowers in clusters up to 2 ft.
Macrobotrys	Japanese wisteria (W. floribunda), invasive	Fragrant red-violet flowers in clusters 2-4 ft long.
Rosea	Japanese wisteria (W. floribunda), invasive	Fragrant rose-pink flowers.
Violacea Plena	Japanese wisteria (W. floribunda), invasive	Very fragrant double violet-blue flowers in clusters under 1 ft.
Aunt Dee	Kentucky wisteria (W. frutescens var. macrostachya), native	Light purple flowers; blooms reliably in Iowa.
Blue Moon	Kentucky wisteria (W. frutescens var. macrostachya), native	Fragrant light blue flowers on 8-12 inch clusters; a Minnesota selection known for extreme cold hardiness.
Clara Mack	Kentucky wisteria (W. frutescens var. macrostachya), native	White flowers; blooms reliably in Iowa.

Diseases and problems

Root rot, Iron chlorosis, Armillaria root rot

In the kitchen

Safety: Seeds and pods are poisonous: eating even one or two pods can cause nausea, vomiting, stomach pain and diarrhea, and the roots, bark and stems are listed as toxic too (NC State). Keep children away from the pods.

Pets: Toxic to dogs, cats and horses (NC State lists all three as at risk): wisterin (a saponin) and lectin, mainly in the seeds and pods, can cause nausea, vomiting, belly pain, depression and diarrhea.

Sources

Photo: Photo: David J. Stang / Wikimedia Commons, CC BY-SA 4.0 (CC BY-SA 4.0). Photo resized for the web.

Planting dates and advice are general guidance; check with your local Cooperative Extension office for your area.