A Guide to Wisterias: How to Plant, Prune, and Care for One
What Is a Wisteria?
Wisterias are one of the most spectacular spring-blooming perennials and are actually very large woody vines. They are a genus—with about ten species—of flowering plants in the pea family. Some species are native to the United States—including the American and Kentucky—but the two most popular wisterias are the Chinese and Japanese varieties. The Chinese wisteria was brought to the United States for horticultural purposes in 1816, while the Japanese wisteria was introduced around 1830.
With their abundance of foot-long panicles of flowers—most commonly in lilac blue—they are traffic stoppers. I once had an elderly woman with a carload of grandchildren stop in front of my house and ask if they could smell my wisteria. The beauty of these plants in full bloom has been immortalized in Tiffany stained glass, which often depicts irises blooming in the foreground—a nice combination in the garden. Plan for your wisteria to be around for a very long time—some of them live for over 100 years!
How Long Does it Take for One to Bloom for the First Time?
They usually bloom within three to five years of planting. However, some can take up to 15 years—this is especially true if you plant one from a seed (I discuss this more in-depth further down in the article). You can help speed up the blooming process by properly planting, pruning, and caring for it, which I'll show you how to do in this article.
What Are the Most Common Species?
Chinese (Wisteria Sinensis)
Japanese (Wisteria Floribunda)
American (Wisteria Frutescens)
Kentucky (Wisteria Macrostachya)
Silky Wisteria (Wisteria Brachybotrys)
How tall does it grow?
10-25 feet or higher
20-30 feet or higher
Does it produce a fragrant smell?
most noticeable pleasant smell
flowers are heavily scented
flowers are not as heavily scented
flowers are fairly scented
When is the flowering period?
early spring to early summer
mid-spring to early summer
Heaviest in late spring, repeating sporadically in summer
late spring through early summer
How long are the racemes that hold the flower clusters?
approx. 12 inches
approx. 12 inches long (some can have dramatic racemes up to four feet long)
approx. six inches
approx. eight inches
approx. four to six inches
What sets it apart?
not as cold hardy as the Japanese; flower clusters open all at once; flowers last the longest; vines twist counterclockwise
most color variety; great for gardeners in northern climates; vines twist clockwise; bright flower clusters
native to eastern U.S.; flowers are lilac-blue; doesn't grow as aggressively as the Asian varieties
native to the Midwest; most cold-hardy species; latest bloom time; re-blooms throughout the growing season
great choice for a house wall or large pergola; large pale lilac flowers with a conspicuous white spot; soft, hairy leaves;
Where Should You Plant a Wisteria?
These vines aren’t that difficult to control, especially if you’ve planted it in a good spot. Below are some tips on where and where not to plant one.
Locations Where Your Plant Will Thrive
- A sunny spot: Wisterias need to be planted in a location that gets at least six hours of sunlight on a daily basis.
- Easily accessible: It's a good idea to plant it in a place where you can easily mow around the base of the vine/tree and places that are frequented. By the latter, I mean that it is best not to plant it in an “out of sight, out of mind” location. It should be in a location where any rambunctious tendencies are noticed early.
- An island bed surrounded by other flowering plants: This is a good location since it's an area that will get regular maintenance. However, you want to make sure it doesn't overwhelm the other plants.
- Near a driveway: Planting a wisteria near a driveway also works to draw your attention to its pruning needs.
- Garden arch or small pergola: For most home gardeners, they are best planted either on a very strong support, such as a sturdy garden arch or small pergola, or trained in the form of a tree. Vertical supporting members for a vine should be four-by-fours (at least) and horizontal supports need to be made of strong framing lumber. These vines are very heavy when mature.
- Problem areas: Because of its exuberant growth habits, a wisteria is a good plant for problem areas, bearing in mind that it requires full sun if you want it to bloom.
- Well-drained soil: While the vine will tolerate most soil conditions, it does require deep, rich soil that is somewhat moist and allows water to percolate quickly.
Locations You'll Regret in a Year or Two
- Large and high arbor or pergola: Older gardeners—or any gardener who doesn’t want to be bothered with onerous maintenance chores—will probably not want to grow one on a large and high arbor or pergola since this would mean that pruning would have to be done on a stepladder. A wisteria grown on a small arbor would probably not be a serious maintenance problem, however.
- Next to the house: As with any vine, it should not be planted next to the house, with the idea of letting it clothe the exterior walls in glory. When vines of any kind are allowed to grow up the exterior walls of a house, they will work their way under the siding and eventually pull it loose. I understand that it’s okay to grow vines on stone or brick exteriors, but I would be afraid for the wooden shutters and window frames—and afraid of pruning on an extension ladder. But that’s just me. Maybe you have a gardening staff, a list of adventurous roofers, and great homeowner’s insurance.
- On a lightweight garden arch: While I’ve seen wisterias grow successfully on a simple lightweight garden arch, this is probably not a good long-term plan. As the vine matures, the weight will eventually overwhelm such a structure.
- Near spring bloomers: Spring bloomers—such as irises, English daisies, creeping phlox, and dianthus—that need to be fertilized in early spring to produce a good display should not be planted too close to wisterias because this could prevent the vine from flowering (I explain this more in detail further down in the article).
When I first moved into my present house (a fixer-upper), the entire front yard was a gravel driveway. There was no front yard in the traditional sense; the entire width of the house, from doorstep to street, was a gravel parking area. This setup was, of course, unattractive; I set about creating a large island bed, roughly in the middle of this barren stretch of gravel that allowed for parking on both sides. I used stackable blocks (like the ones used for retaining walls) two blocks high and shaped into a rough oval, and filled it in with bagged compost/manure. If I had it to do over, I would use natural stone since it has much more eye appeal, but for many island beds, you can’t beat these stackable blocks for ease of construction. In this island bed, I planted flowers, bulbs, and a single wisteria that was staked to train it into a tree form."
Should I Grow a Wisteria From Seed?
Inside the seed pods are large seeds that are easy to germinate. The germination rate is pretty close to 100%, but blooming may not occur for 10-15 years, if ever.
The temptation to grow this plant from seed to give away to friends and neighbors is hard to resist. One year, before I read that plants grown from seed are often slow to bloom, I planted quite a few seeds in pots, and I had many eager takers. I hope I did not doom those friends and neighbors to 15 years of frustration while waiting for the plants to bloom.
I also gave away seedlings that came up in neglected flowerbeds in my yard. One of these plants was sprawling on the ground in full bloom before I noticed it—so I guess it must have been two or three years old. So, clearly, some seed-grown plants bloom young, but it's best to avoid this method.
How Can I Use the Seeds?
You may find the seedpods useful for craft projects. Spraypainted gold or silver, they aren’t half bad as Christmas-tree ornaments.
Fun Piece of Trivia
There is a 100-year-old wisteria in Sierra Madre, California, that is so large that it has received a place in the Guinness Book of Records as the largest blossoming plant in the world. This amazing vine is more than one acre in size and weighs 250 tons.
How to Propagate Wisteria From Cuttings
If you’d like to give away one of these plants—or feel you’d like another plant or two for yourself—it is easy to grow them from cuttings. This approach will ensure a new tree or vine that will not take forever to bloom.
- Take cuttings from green softwood in late spring or summer. Cuttings should be six to eight inches long and have a few sets of leaves.
- Remove leaves from the lower half of the cutting, but keep two or three sets of leaves on the top half. The places where leaves were removed (leaf nodes) are where the roots will develop.
- Trim the bottom of the cutting so that the lowest node where leaves were removed is ½ to ¼ inch from the bottom end of the cutting. Make this bottom cut at an angle.
- Make a two-inch deep hole in a moist, soilless potting mixture. If you are using a six-inch pot, you can fit up to five cuttings in one pot—and taking several cuttings is good insurance. Separate pots for each cutting may be the best idea, since you may want to grow them in pots to avoid planting out in very hot or dry weather, or you may want to give some away.
- Put the bottom ends of the cuttings into the holes and firm the soil around them. Cover the pot with plastic. A two-liter plastic soda bottle with the bottom cut out will work to cover a six-inch pot, or you can use a plastic bag supported by sticks so that the plastic can’t come in contact with the leaves.
- Put the potted cutting in a sunny spot, but out of direct sunlight, and water regularly to make sure the soil doesn’t dry out. The cuttings should root in four to eight weeks.
Once the cuttings have rooted, it would be best to grow them in pots, gradually hardening them off (while making sure they have plenty of water). Usually, it is too hot, and sometimes too dry, for successful transplanting into the ground in mid and late summer. It’s best to wait for the heat to let up before planting them in the early fall. Make sure to water the newly planted cuttings regularly once they’re planted.
Plants grown from stem cuttings can be expected to bloom in two to three years, at which point you will be the envy of the neighborhood.
How to Take Care of Your Plant
In the early spring, you should apply a layer of compost under the plant along with a two-inch layer of mulch to help retain moisture and control weeds. Also, for the first year, if you live in an area that receives less than an inch of rain every week, be sure to water your wisteria. Once your vine is established, it can withstand surprise frost, garden pests, inclement water, and drought—so pruning will be your main concern.
How Do You Deal With Its Aggressive Growing Habits?
Wisterias grow easily. In fact, the usual complaint about them is that they grow too easily—and can be difficult to control.
- Remove unwanted shoots immediately: My wisteria—which I trained into a small tree—sends up unwanted shoots from the base, which must be removed as soon as they are noticed.
- Provide a sturdy support: It has also shown a certain predisposition to want to lean. Without support, it would probably just lie down on the ground. The solution to this difficulty is to provide a sturdy support to keep the trunk aimed in a generally upward direction.
- Cut back on overgrowth: My “small” wisteria has a tendency to produce an overabundance of top growth that, if not cut back, will eventually engulf everything in its immediate vicinity. Since it's planted next to a driveway, it often seems bent on engulfing my daughter’s car whenever I neglect the pruning for too long.
- Prune aggressively: You decide the size and shape. Don’t be afraid to prune them aggressively. You won’t hurt them. If you’re going to worry about them, worry that they’ll engulf the neighborhood.
Can You Prune and Train a Wisteria to Look Like a Small Tree?
I think the easiest way to grow this type of plant is to train it into a free-standing tree (you can even make it into a bonsai!). In three or four years, it will grow into a cute, little ornamental tree that is six to eight feet tall. In ten years or so, it should be eight to ten feet tall.
The chief advantage of training it to a tree form is that there is no need to build a sturdy and expensive structure to support it. Here's a simple way:
- Stake the main stem of the plant to a sturdy post set securely in the ground and remove all unwanted growth along the trunk, allowing only top growth.
- As the tree grows taller, growth along the trunk can be removed higher up on the plant, thus creating a taller trunk.
The key to doing this successfully is the sturdy post (such as a four-by-four) set securely in the ground. As the tree grows larger and heavier, it may lean so heavily on a less sturdy and secure post that it will push it over. This will result in your tree leaning sharply to one side, and it could even decide to lie flat on the ground.
Since I did not take the precaution of staking my wisteria to a sturdy enough post, I wound up having to prop it up. I wedged the heavy base of an old birdbath against the trunk. This is a two-person job: One person pulls the small tree so that the trunk is more or less vertical while a second person wedges the base of the old birdbath against it.
Also, if your tree begins to list a little to one side, there is no reason why you can’t just cut away any offending branches (even half the tree, if you feel like it) leaving behind those that are disposing of themselves more or less vertically. You can’t hurt a wisteria and the free-form wandering and general upward curves will look charming as the tree matures.
Pruning helps to encourage bloom, and both summer pruning and late winter/early spring pruning are recommended. For the first few years, as the tree puts on growth, pruning will mostly be a matter of controlling top growth and keeping the “trunk” free of unwanted growth.
There will be no mystery to summer pruning; just cut away overly exuberant growth to maintain a tidy shape. All you are trying to achieve is to make your wisteria look like a pretty little tree—and keep it from engulfing your car during the night.
How to Prune It in the Summer
Summer pruning will be an ongoing business unless you are okay with letting the top of the tree assume very large proportions. In this case, the top of the tree will be all over the place, including weeping to the ground and waving restless tentacles in all directions. You’d have something quite out of the ordinary there.
How to Prune It in the Winter/Early Spring
In addition to summer pruning, it’s best to prune your plant pretty hard in late winter/early spring. By this, I mean that dead wood should be removed and long, thin branches should be cut back quite a lot. It’s hard to be specific and say something like, “Cut back long, thin branches by one-half to two-thirds,” because I don’t know how much you pruned it in summer. Just cut them back so that the tree’s canopy is fairly small and tidy looking. You may also want to remove some smaller branches entirely, to reduce crowding.
You can also prune after the flower buds are clearly noticeable in spring—or prune both before and after buds have clearly formed. (Frankly, you can prune a wisteria any time you feel like it). Just be mindful of cutting away any buds unless it’s necessary to the tree’s shape, and be careful about knocking the buds off by accident. Late winter/early spring is also a good time to raise the tree’s canopy by removing branches from the upper part of the trunk.
Then it's time to primp your tree. This is so much fun! It's a great place for a hummingbird feeder—and a couple of brightly painted birdhouses—and other decorations, too, such as wind chimes or sun-catchers. It’s also a nice place to hang a winter birdfeeder.
How Do I Control My Vines?
If you're looking to have your vines climb a structure in a controlled manner, you'll first want to let your young wisteria shoot vines around the posts. Then you can secure these vines using either galvanized wire and eye hooks or gardening twine. Make sure you don't tie the twine too tight or it will injure your plants and put too much stress on your structure. Prune the tips to encourage the side branches to grow, and before you know it, you'll be able to remove the ties and you'll be left with a controlled vine. It's important to keep up with pruning and trimming though!
How Toxic Are These Vines?
All parts of the wisteria plant are toxic to humans, pets, and livestock because they contain two toxins: lectin and wisterin. These substances can cause nausea and diarrhea if consumed in large amounts. Always wear gloves when trimming and pruning, and wash your hands after handling a wisteria.
The most deadly parts of the plant are the seeds and seedpods—so if you have children or pets, it's a good idea to remove these parts after the plant has flowered. The seedpods don't taste bad or immediately cause symptoms, so a child or pet may inadvertently consume a large amount. Call your local poison control center in case of ingestion.
Why Isn't My Wisteria Blooming?
One of the most frequent complaints about these plants is that the darned things don't bloom for many years after planting—and sometimes mature ones never bloom.
Here are the usual causes of failure to bloom and suggested solutions:
- Wisterias grown from a seed are said to often take as long as 15 years to bloom, so most sources say you should only grow ones from grafted plants or cuttings of cultivated varieties of proven floriferousness and early bloom.
- Plants that are slow to bloom can often be coaxed into flowering by a fairly hard pruning. An old, neglected plant may need very hard pruning. You can also cut back the rampant shoots every two weeks during summer to increase blooming. As a desperation measure for old and stubborn non-bloomers, root pruning is often suggested—this is where you dig around the plant with a shovel to sever some of the roots. If you are able to damage about half of the roots, the bush will be shocked into flowering. Don't worry about hurting it—that's pretty hard to do that!
- They should not be fertilized with nitrogen, as this tends to produce heavy foliage growth and no flowers. The best fertilizer for this type of plant is phosphorus, in the form of bone meal. For this reason, if your wisteria is the centerpiece of a flowerbed, as mine is, give it a little space so that you can fertilize the flowers without giving the vine a dose. Alternatively, if you have flowers planted near yours, hold off fertilizing them until it's already blooming. Flowers that bloom later in the summer, such as hibiscus, balloon flower, portulaca, and daylilies, can be given their dose of fertilizer a little later in spring without harm.
- Remember that these plants need full sun. They won’t bloom in full or partial shade.
Questions & Answers
Can I grow wisteria in a house with a solar lamp?
I don't know for sure. I started some cuttings this spring, and they took hold and seemed quite happy for about a month in a sunny window until I moved them outdoors.
Wisteria is very resilient, but it really isn't an indoor plant, so I would not expect it to do well indoors, long-term.
Is wisteria deer resistant?
Both American wisteria and Japanese wisteria are deer resistant.
I live in Senegal, West Africa. We have a hot and dry season, plus a scorching and very humid season. Would I be able to grow wisteria in such a climate?
I honestly don't know if you could grow wisteria in West Africa. Wisteria can become rampant in some hot and humid climates. My guess is that it would do well if you gave it sufficient water during the dry season.