Shrub · Fabaceae
Wisteria
Wisteria sinensis
Give it full sun, a heavy support, and two hard prunings a year, and wisteria drips with flowers each spring.
Full sun
Every 5–10 days
1095–2555 days
USDA 5–9
Overview
Few climbers put on a show like wisteria in full bloom, when long racemes of blue-violet flowers hang in curtains over an arbor. It is a woody, twining member of the pea family, and the same vigor that makes the display so heavy also makes the plant a handful. A mature vine is closer to a small tree than a delicate climber.
Two Asian species dominate gardens. Chinese wisteria twines counterclockwise and opens its flowers almost all at once, while Japanese wisteria twines the other way and unfurls its racemes slowly from base to tip. Both are beautiful but invasive across much of the eastern US, which is why native American and Kentucky wisteria are worth a serious look.
Wisteria asks for patience and a strong hand. A young plant can sulk for years before it flowers, and once it starts growing it will strangle trees and pull down gutters if you let it. Give it full sun, a sturdy dedicated support, and hard pruning twice a year, and it rewards the effort for decades.
Care
The short version: full sun, a very strong support set well away from trees and the house, and lean soil with little or no feeding. Water deeply while it establishes, then prune hard in both summer and winter to keep it in bounds and bring on the flowers.
Light
Wisteria flowers best in full sun, and a site that gets direct light all day is what fills the vine with blooms. It will tolerate partial shade, but shade is one of the main reasons a healthy-looking plant never flowers.
Water
Keep the soil moist but well drained while the plant is settling in, watering deeply during dry spells. Once established it shrugs off drought fairly well, so let the top inch or so dry between waterings rather than keeping it soggy.
Soil
Wisteria is not fussy about soil and adapts to clay, loam, or sand as well as wet or dry ground. Aim for moist, well-drained loam with a pH between 6.0 and 7.0 and it will do the rest.
Temperature
This is a tough, cold-hardy vine that handles a wide range, roughly -20°F to 100°F (-29°C to 38°C). The main weather risk is a late spring frost, which can wipe out the flower buds just before they open.
Humidity
Ordinary outdoor humidity suits wisteria fine, so there is no level to manage. What matters far more is air and light reaching the vine, which means keeping its rampant growth thinned out.
Feeding
Go very light here, or skip feeding altogether. Wisteria needs little, and excess nitrogen pushes out leaves instead of flowers, so use only a low-nitrogen feed in spring if you feed at all.
Pruning
Prune hard twice a year to keep the vine in check and bring on bloom. In summer cut the long whippy shoots back to five or six leaves, and in winter shorten those same shoots to two or three buds, cutting away anything girdling its support.
Repotting
Wisteria belongs in the ground rather than a pot, so it isn't really repotted. On an established plant, root pruning can push a stubborn vine into flowering, and few or no blooms despite leafy growth is the sign it may help.
Size & spacing
Give wisteria serious room, because it climbs 10 to 25 feet (3 to 7.5 m) tall and spreads anywhere from 4 to 30 feet (1.2 to 9 m) across. Set it on its own heavy support well clear of trees, walls, and other plants.
When to plant
Wisteria is a long-lived woody vine, so the timing that matters is planting, not a yearly sowing. Set new plants out in spring or fall, then wait, because flowers can take several years to arrive and arrive in mid-to-late spring once they do.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall
- Harvest: Mid-to-late spring (April-May)
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Most wisteria problems come down to a plant that won't bloom or one that grows too well for its own good. Read the symptom, check the plant's age and where it sits, then act before the vine takes over. The fixes below cover the three issues gardeners hit most.
Heavy stems strangling trees and crushing structures
Wisteria is a massive woody twiner that can reach over 60 feet and outgrow almost any support you give it. Left to its own devices it wraps tight around tree trunks and chokes them, and its weight bows or snaps trellises, gutters, and downspouts. Give it a heavy, dedicated arbor well away from the house, prune hard twice a year, and cut free anything it tries to climb that you didn't intend.
Fix:
- Provide a very strong, sturdy dedicated support (heavy arbor or metal structure)
- Prune hard twice a year and cut away any stems twining around trees, gutters, or downspouts
- Remove the plant entirely if it is engulfing trees or buildings
Vines escaping into the woods and killing native trees
The Asian species are invasive across the eastern and southeastern US, spreading by seed, runners, and stems that root wherever they touch the ground. Once loose they form dense thickets and shade out or pull down native trees. Cut escaped vines back to the root and keep removing the resprouts, and plant native American wisteria instead where natural areas are nearby.
Fix:
- Cut vines close to the root and repeatedly remove resprouts through the season
- Apply an appropriate systemic herbicide to cut stems in spring or summer where permitted
- Replace with a native, non-invasive alternative such as American wisteria (Wisteria frutescens)
Lush leafy vine that won't bloom
A wisteria that climbs hard but never flowers is usually just too young. Seedlings often take 3 to 7 years or more before the first racemes appear. Too much nitrogen, deep shade, or a late spring frost on the buds can all hold it back as well, so move it into full sun, stop feeding it, and prune twice a year to build flowering spurs.
Fix:
- Be patient and let the plant mature; grafted or already-blooming nursery plants flower sooner than seedlings
- Stop applying nitrogen fertilizer
- Move or train the vine into a full-sun position
- Prune correctly twice a year (summer and winter) to build flowering spurs
Toxicity
Every part of wisteria is toxic, and the velvety seed pods and bean-like seeds are the most dangerous of all. They hold a lectin called wisterin along with toxic glycosides, and because the pods look like edible beans they have repeatedly poisoned children. Keep the seeds and pods away from pets, livestock, and kids, and clear fallen pods from the ground.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Moderate
A cat that chews the pods or seeds tends to vomit, sometimes with blood, and then comes the diarrhea, low energy, and dehydration. The seeds and pods are the usual culprits.
Dogs Moderate
Dogs are drawn to the bean-like pods and pay for it with heavy vomiting that may be bloody, loose stools, drooling, and a flat, dull mood. Watch for dehydration as the upset stomach drags on.
Horses Moderate
Eating any part leaves a horse off its feed and dull, with vomiting, diarrhea, and drooling. The toxin runs through the whole plant, not just the seeds.
Rabbits Toxic
Wisterin and the plant's glycosides make every part unsafe for rabbits. Even a small nibble can bring on drooling, a painful gut, and runny droppings, so keep them away from it entirely.
Livestock Toxic
Cattle, goats, and sheep that graze the foliage, pods, or seeds can suffer severe stomach upset, drooling, and dehydration. Fence the plant off from any pasture.
Birds Toxic
The seeds and pods are toxic to birds, and the pods look just like the beans they would normally peck at. Expect vomiting, weakness, and dehydration if any is eaten.
People Caution
The velvety pods look like edible bean pods and have poisoned children who ate the seeds. Even a couple of seeds can bring on severe vomiting, belly pain, bloody diarrhea, drooling, and dehydration, so keep kids well clear of them.
The pods resemble edible beans and have poisoned children; keep seeds and pods away from kids and pets.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Wisteria comes down to a choice between the showy but invasive Asian species and the better-behaved natives. These four cover the plants you are most likely to find.
Wisteria sinensis (Chinese wisteria)
This twines counterclockwise and opens fragrant blue-violet to purple, pink, or white racemes 6 to 12 inches long almost all at once before the leaves appear, but it is invasive across the eastern US.
Wisteria floribunda 'Macrobotrys' (Japanese wisteria)
It twines clockwise and carries exceptionally long red-violet racemes, reported up to 2 to 4 feet, that open gradually from base to tip, and while it is cold hardy it is also invasive in the eastern US.
Wisteria frutescens 'Amethyst Falls' (American wisteria)
A native, far less aggressive choice with compact 4 to 6 inch lavender-purple racemes in May that bloom on new wood, so it often flowers while still young.
Wisteria macrostachya 'Blue Moon' (Kentucky wisteria)
A very cold-hardy native selection whose silvery-blue racemes can rebloom through the season, making it a non-invasive pick for northern gardens.
How to propagate
You can multiply wisteria from a pegged stem, a summer cutting, or seed, though only the first two give you a plant that flowers like its parent.
LayeringEasy
Spring to summer · Several months to a year to root
Layering is the most reliable way to copy a wisteria. Peg a low, flexible stem down into the soil in spring or summer and wait, since it can take several months to a full year to root. The new plant keeps the exact flowering traits of its parent.
Stem cuttingsModerate
Summer (softwood/semi-ripe) · Several weeks to root
Take softwood or semi-ripe cuttings from the current season's growth in summer and they root in a few weeks. This route also preserves the cultivar, so the plant you raise blooms just like the one you took it from.
SeedModerate
Spring · Many years to first bloom
Seed is easy to germinate in spring but the worst route for impatient gardeners, since seedlings are variable and often take 7 or more years to flower. The seeds are also toxic, so handle them with care and keep them away from children and pets.
Myths
Feeding wisteria plenty of fertilizer makes it bloom.
High-nitrogen fertilizer does the opposite, pushing out leaves at the expense of flowers. Most wisteria blooms better when it is left unfed. Full sun, correct twice-yearly pruning, and a little maturity are what actually bring the flowers.
All wisterias are invasive, so none are worth planting.
Only the Asian species, W. sinensis and W. floribunda, run wild in the eastern US. Native American wisteria (W. frutescens) and Kentucky wisteria (W. macrostachya) are far better behaved and give you the same draping flowers without the threat to surrounding woodland.