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
Not many climbers can match a wisteria in full bloom, when those long racemes of blue-violet flowers hang down like curtains over an arbor. It's a woody, twining member of the pea family, and the same energy that makes the show so heavy is what turns the plant into a bit of a handful. Think small tree, not delicate little climber.
Two Asian species run the show in most gardens. Chinese wisteria twines counterclockwise and opens nearly all its flowers at once, while Japanese wisteria goes the other way and unrolls its racemes slowly from base to tip. Both are gorgeous but invasive across a lot of the eastern US, so why not give the native American and Kentucky wisterias a real look?
Wisteria asks for two things: patience and a firm hand. A young plant can sulk for years before it flowers, and once it gets going it'll strangle trees and pull down gutters if you let it. Give it full sun, a sturdy support of its own, and a hard prune twice a year, though, and it'll pay you back for decades.
Care
The short version: wisteria wants full sun, a really strong support set well away from trees and the house, and lean soil with little or no feeding. Water it deeply while it's settling in, then prune it 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 spot that catches direct light all day is really what packs the vine with blooms. It'll put up with partial shade, but shade is one of the big reasons a healthy-looking plant just never flowers.
Water
Keep the soil moist but well drained while the plant's getting established, and water it deeply whenever things dry out. Once it's settled it handles drought pretty well, so let the top inch or so dry out between waterings instead of keeping it soggy.
Soil
Wisteria isn't picky about soil and takes clay, loam, or sand, wet ground or dry, all in stride. Shoot for moist, well-drained loam with a pH between 6.0 and 7.0 and it'll take care of the rest.
Temperature
This is a tough, cold-hardy vine that handles a big range, roughly -20°F to 100°F (-29°C to 38°C). The one weather worry is a late spring frost, which can knock out the flower buds right before they open.
Humidity
Regular outdoor humidity suits wisteria just fine, so there's no level to fuss with. What matters way more is air and light getting to the vine, which just means keeping that rampant growth thinned out.
Feeding
Go easy here, or honestly just skip feeding altogether. Wisteria needs very little, and too much nitrogen pushes out leaves instead of flowers, so if you feed at all, stick to a low-nitrogen one in spring.
Pruning
Prune it hard twice a year to keep the vine in line and bring on bloom. In summer, cut the long whippy shoots back to five or six leaves, then in winter shorten those same shoots to two or three buds, snipping away anything girdling its support.
Repotting
Wisteria lives in the ground, not a pot, so it isn't really repotted. On an established plant, root pruning can nudge a stubborn vine into flowering, and few or no blooms despite loads of leaves is your hint it might help.
Size & spacing
Give wisteria some serious elbow 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's a long-lived woody vine, so what matters is planting, not some yearly sowing. Set new plants out in spring or fall, then be ready to wait, because the flowers can take a few years and they'll show up 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 headaches boil down to a plant that won't bloom or one that grows a little too well for its own good. Read the symptom, check how old the plant is and where it's sitting, then step in before the vine takes over. The three fixes below cover what gardeners run into most.
Stems that choke trees and wreck structures
Here's the thing about wisteria: it's a big woody twiner that can top 60 feet and outgrow just about any support you hand it. Left alone, it winds tight around tree trunks and chokes them, and all that weight bows or snaps trellises, gutters, and downspouts. So give it a heavy, dedicated arbor well away from the house, prune it hard twice a year, and cut loose anything it tries to climb that you didn't mean it to.
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 sneaking off into the woods
The Asian species are invasive all over the eastern and southeastern US, and they get around three ways at once: by seed, by runners, and by stems that root wherever they touch the ground. Once they're loose they pile up into dense thickets and shade out or drag down native trees. Cut escaped vines back to the root and keep pulling the resprouts, and if there's wild woodland nearby, go with native American wisteria instead.
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)
Lots of leaves, still no flowers
Got a wisteria that climbs like crazy but won't bloom? Nine times out of ten it's just too young, and a seedling can need 3 to 7 years or more before those first racemes turn up. Too much nitrogen, heavy shade, or a late spring frost on the buds can hold it back too, so move it into full sun, quit feeding it, and prune twice a year to build up the 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 riskiest of the lot. They carry a lectin called wisterin plus some toxic glycosides, and since the pods look like edible beans, they've poisoned kids more than once. Keep the seeds and pods away from pets, livestock, and children, and clear any fallen pods off the ground.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Moderate
If a cat chews the pods or seeds, which are the usual troublemakers, it'll usually throw up, sometimes with a bit of blood, and then come the diarrhea, low energy, and dehydration.
Dogs Moderate
Dogs can't seem to resist those bean-like pods, and they pay for it with heavy vomiting that might be bloody, loose stools, drooling, and a flat, dull mood. Keep an eye out for dehydration if the tummy trouble hangs around.
Horses Moderate
The toxin's in the whole plant, not just the seeds, so a horse that eats any of it goes off its feed and turns dull, with vomiting, diarrhea, and drooling.
Rabbits Toxic
Wisterin and the plant's glycosides make every part off-limits for rabbits. Even a little nibble can bring on drooling, a sore belly, and runny droppings, so it's best to keep them away from it completely.
Livestock Toxic
Cattle, goats, and sheep that graze the leaves, pods, or seeds can end up with serious stomach upset, drooling, and dehydration, so fencing the plant off from any pasture is the way to go.
Birds Toxic
The seeds and pods are toxic to birds, and here's the catch: the pods look just like the beans a bird would normally peck at. Expect vomiting, weakness, and dehydration if any gets eaten.
People Caution
Those velvety pods look a lot like edible bean pods, and they've poisoned kids who ate the seeds. Even a couple of seeds can trigger severe vomiting, belly pain, bloody diarrhea, drooling, and dehydration, so keep little ones well away from 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
Picking a wisteria really comes down to the showy but invasive Asian species or the better-behaved natives. These four cover the ones you're most likely to run across.
Wisteria sinensis (Chinese wisteria)
This one twines counterclockwise and pops open fragrant blue-violet to purple, pink, or white racemes 6 to 12 inches long almost all at once before the leaves show up, though it's invasive across the eastern US.
Wisteria floribunda 'Macrobotrys' (Japanese wisteria)
It twines clockwise and hangs really long red-violet racemes, said to reach 2 to 4 feet, that open bit by bit from base to tip, and while it's plenty cold hardy it's also invasive in the eastern US.
Wisteria frutescens 'Amethyst Falls' (American wisteria)
A native that's way less pushy, with tidy 4 to 6 inch lavender-purple racemes in May that bloom on new wood, so it often flowers while it's still young.
Wisteria macrostachya 'Blue Moon' (Kentucky wisteria)
A super cold-hardy native whose silvery-blue racemes can rebloom through the season, which makes it a nice non-invasive pick for northern gardens.
How to propagate
Want more wisteria? You can raise it from a pegged stem, a summer cutting, or seed, though only the first two hand you a plant that flowers just like its parent.
LayeringEasy
Spring to summer · Several months to a year to root
Layering's the most reliable way to make a copy of a wisteria you like. Just peg a low, bendy stem down into the soil in spring or summer and hang tight, because it can take several months to a full year to root. The upside? The new plant flowers exactly like its parent.
Stem cuttingsModerate
Summer (softwood/semi-ripe) · Several weeks to root
Grab softwood or semi-ripe cuttings from this year's growth in summer and they'll root in a few weeks. This way keeps the cultivar too, so whatever you raise blooms just like the plant it came from.
SeedModerate
Spring · Many years to first bloom
Seed sprouts easily enough in spring, but it's the slow lane if you're impatient, since seedlings are all over the place and often need 7 or more years to flower. The seeds are toxic too, so handle them carefully and keep them away from kids and pets.
Myths
Feeding wisteria plenty of fertilizer makes it bloom.
It's actually the opposite, since high-nitrogen fertilizer just pushes out more leaves instead of flowers, and most wisteria blooms better when you leave it unfed. Full sun, the right twice-a-year pruning, and a little maturity are what really bring on 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) behave a whole lot better, and they give you the same draping flowers without putting nearby woodland at risk.