In the spring, wisteria blooms ferociously, producing clusters of lilac-colored flowers on fresh growth that develops from spurs off the main stalks. Check out our Wisteria Growing Guide for more information on wisteria maintenance, including planting and pruning.
Wisteria is a long-living vining shrub with cascades of blue to purple blossoms that, in the spring and early summer, look stunning hanging from a pergola or archway. However, this vine is known to grow fairly heavy and to grow quickly and aggressively, frequently reaching lengths of more than 30 feet. It’s advised not to put wisteria vines too close to your home since they will squirm their way into any crack or crevice they can find.
Beautifully fragrant wisteria flowers offer a feast for the senses. A brown, bean-like pod remains on the plant during the winter after flowering. There are only blooms on fresh growth.
Note: Be careful when planting wisteria! The wisteria plant contains lectin and wisterin, which are poisonous to people, animals, and even pets. If taken in significant quantities, these poisons can result in anything from nausea and diarrhea to death.
Is Wisteria an Invasive Plant?
The wisteria species Wisteria sinensis and Wisteria floribunda, which are not native to North America, are regarded as invasive in several areas. If you want to add a new wisteria to your garden, we advise choosing one of the native North American varieties, such as American wisteria (Wisteria frutescens) or Kentucky wisteria (Wisteria macrostachya), which are excellent alternatives to the Asian species.
Do you want to know how to distinguish between North American and Asian species?
While North American wisteria is not quite as aggressive in its growing tendencies and has smooth seed pods and fruits in addition to more-or-less cylindrical, bean-shaped seeds, Asian wisteria is an aggressive grower with fuzzy seed pods. Another distinction is that the flowers of American and Kentucky wisterias appear in the late spring after the plant has begun to leaf out, whereas those of Chinese wisteria do not.
When to Plant Wisteria
- Plant during the plant’s dormant season in the spring or fall.
- Wisteria can be grown from seed, although plants from seeds frequently take many years to mature and begin to bloom. It is advised to buy wisteria plants that are already established or to begin with a cutting.
Where to Plant Wisteria
- Put a plant in full sun. Even while wisteria will grow in some shade, it won’t likely bloom. Sunlight is necessary.
- Wisteria should be grown in fertile, wet, but well-draining soil.
- Wisteria will grow in most soils unless it is in bad condition, in which case you need add compost. Find out more about soil improvements and getting the soil ready for planting.
- Because wisteria grows swiftly and can easily engulf its neighbors, pick a location apart from other plants.
- Additionally, wisteria is renowned for encroaching on and infiltrating surrounding buildings like homes, garages, sheds, and so on. We highly advise against growing wisteria too near your house!
- Wisteria vines need a very strong support, like a metal or wooden trellis or pergola, to climb on. Plan carefully and use substantial materials to construct your structure because mature plants have been known to become so heavy that they destroy their supports.
Wisteria looks gorgeous growing up the side of a house, but use caution when planting it because it is a very strong vine that will get into any crack or gap!
Caring for Wisteria
- Apply a 2-inch layer of mulch and a layer of compost under the plant each spring to keep moisture in and keep weeds at bay.
- Phosphorus is often used by gardeners to promote flowering. In the spring, work a few cups of bone meal into the soil. Then, in the fall, add some rock phosphate. Study up on soil amendments.
- If you get less than an inch of rain each week, water your plants. (To determine how much rain you are receiving, set an empty food can outside and use a measuring stick to gauge the depth of the water.)
- During the summer, try pruning the out-of-control shoots every two weeks for more blooms.
- In the late winter, prune wisteria. Remove at least half of the growth from the previous year, leaving only a few buds on each stem.
- Also prune in the summer after customary flowering if you prefer a more formal appearance. On fresh growth, spurs from the main shoots of the wisteria develop its blossoms. Trim back every new shoot from this year to a spur, leaving no more than 6 inches of growth. So that there are no free, trailing shoots, the entire plant can be trained, roped in, and otherwise organized throughout this procedure.
- Mature plants that have been cultivated informally require little to no more pruning. However, for a plant that has been formally trained, side branches should be pruned back in the summer to 6 inches, then again in the winter to 3 buds.
- Possess you a fresh wisteria? After planting, aggressively prune the vine. Then, the next year, trim the main stem or stems to a height of 3 feet from the growth of the previous year. After the framework has grown to its full size, midsummer extension growth should be cut back to where it started that season.
Where shouldn’t wisteria be grown?
In order to support the massive vine, the wisteria’s root system extends out widely and dives deep. Do wisteria roots exhibit aggression? Yes, wisteria’s root system is highly aggressive. Avoid planting wisteria next to walls or walkways because of its extensive and strong root system. These are easily harmed by a wisteria’s root system.
Experts advise inserting a corrugated panel about 6 feet (1.8 m) long and several feet (1 m) broad beside the plant to redirect the roots if you find a wisteria close to a building or pathway.
Which month is ideal for wisteria planting?
The best seasons to plant wisteria are spring or fall, and you should put it in full sunlight to ensure that you get to view its lovely blossoms. A wet, well-draining soil is ideal for wisteria.
Types of wisteria:
There are two varieties of wisteria: Asian and American. Although aggressive growers, Asian wisterias are well-known for their stunning blossoms. American wisterias are less aggressive and still produce beautiful blossoms. Compare the most popular wisteria varieties.
Wisteria comes in a range of colors, such as white, pink, and blue tones, in addition to the well-known purple blossoms. If you believe you have seen a yellow wisteria flower, it was probably a golden chain tree (Laburnum).
Wisterias are deciduous, which means that when the weather becomes chilly in the fall, they lose their leaves. The misunderstanding is occasionally brought on by a different vine known as evergreen wisteria (Millettia reticulata).
Avoid planting aggressive wisterias close to your home as they can cause damage and have even been known to destroy buildings.
Wisterias can be grown in full sun or partial shade, but to promote healthy bloom development, make sure the vines get at least six hours of direct sunlight everyday. If you reside in a colder area, pick a planting location that is protected because a heavy spring frost can harm the flower buds.
Create a planting hole that is the same depth as the plant and twice as wide, then level the plant with the soil surface. Because the vines will soon fill in, you should space your plants at least 10 to 15 feet apart along the support structure.
Wisterias don’t need much care once they are planted to promote healthy growth. Water frequently over the first year until the roots take hold.
After planting, wisterias could take some time to come out of dormancy and might not start to leaf until early summer. They will leaf out at the regular time the following spring, but don’t be surprised if they don’t bloom. Wisterias take three to five years to reach full maturity and may not start blooming until then.
Wisterias grow quickly and can reach heights of up to 10 feet in in one growing season. That works out well if you need to quickly cover a fence or pergola but don’t want the vines to take over your landscape. Regular pruning (once in the summer and once in the winter) not only controls wisteria’s growth but also encourages more robust flowering by creating a framework of horizontal branches and causing spurs to grow at regular intervals.
Cut back the current year’s growth to five or six leaves in July or August, or roughly two months after the plant flowers, to get rid of stray shoots and make short branches that will produce flowers the following year. Summer pruning needs to be done more frequently. Re-prune the plant in January or February while it is dormant by removing two or three buds from the growth from the previous year.
The first few years of wisteria’s growth are crucial for creating the desired framework for the plant’s development. As soon as your wisteria begins to grow, start connecting particular lateral shoots to its support structure. You should also cut down any extra growth. An aggressive pruning may be required on elder plants to promote the growth of new branches. Cut down aging branches to the main primary stem to accomplish this. The spaces will soon be filled with new side branches that can be connected back into the support structure.
Visit the Royal Horticultural Society to view a video on how to prune wisteria vines properly.
How is a wisteria vine trained?
My initial apartment search in Brooklyn led me to a one bedroom on a peaceful, tree-lined street. The apartment wasn’t particularly noteworthy, but the structure was: The entire brownstone, windows and all, was covered in an impenetrable mass of wisteria. Some strong wisteria vines, which may grow 10 feet or more in a single season, can easily cover a three-story building. Despite its rambunctious nature, a wisteria in full blossom is one of the most beautiful views.
Wisteria may happily twine, climb, and sprawl over anything in its path for a very long time without any pruning. But a trimming routine becomes an essential task for the gardener who has a small yard and wants to enjoy more obvious and many wisteria flowers. Plan on pruning at least twice a year (once in the summer and once in the winter) for best results. Understanding how the vine develops will also help you succeed.
Not everyone prefers to live without windows, but no one needs to if they plan ahead and make a commitment to routine pruning.
Summer: Cut the long shoots after flowers fade
Since wisteria flowers grow on the growth from the previous year, pruning wisterias twice a year not only keeps them in controllable proportions but also develops a network of short branches close to the building so you can more readily enjoy the blooms. Simply cut the long branches from the current year’s growth back to 6 inches in length in the early summer after the vines have flowered to achieve this. Pruning away root suckers, especially on grafted kinds, and totally removing any branches not required for the main framework of the plant should also be done at this time. Depending on how much time you have and how tidy you want your vine to look, you could choose to prune this way once or more regularly during the summer. Remember that wisteria seedpods are ornamental to many gardeners, so you might wish to leave some wasted blossoms remain.
For winter interest, some seedpods may be left on the vine, but if you bring them inside, high temperatures will force them to explode. The pea-shaped fruit was once utilized by a friend as part of a winter arrangement. The following morning, she discovered her cat hiding in a corner from the flying seeds.
Winter: Prune long shoots down to three or five buds
Trim the long stems that have sprouted after the summer trimming to three to five buds in the late winter. Remove any undesired long shoots from the previous season as well; they will be easier to spot now that the framework is leafless.
To focus energy on flower production rather than vegetative development, even short branches should be pruned to three to five buds.
Why your wisteria may not bloom
Wisterias are infamous for not blooming. Make sure these fundamental cultural prerequisites are satisfied before attempting severe measures.
The decision to go with a seed-grown plant rather than a grafted plant is the most frequent cause of a lack of flowers. While seed-grown vines may take up to seven years before flowering, grafted plants normally blossom within three years.
High winds and late frosts can harm flower buds, particularly those of Wisteria sinensis. Wisteria, on the other hand, blooms best following years with hot summers.
Avoid fertilizer with a high nitrogen content. Wisteria fixes nitrogen in the soil like other legumes do. A surplus of nitrogen might result in poor flowering and excessive leaf growth.
Training a new wisteria on a pergola
The plant’s strength allows it to adapt to various forms. Wisteria can be trained against a structure or lattice, molded into a shrub or standard, or planted on a pergola or arbor. Because of its long blossoms, which dangle dramatically through the top of pergolas and arbors, wisteria floribunda is a popular choice. Since it grows so quickly, like other wisteria species, only one plant is typically required to completely cover a structure. However, placing two vines at the opposite ends of a structure provides it aesthetic balance and allows a gardener to showcase two different cultivars on the same structure.
Planning is essential when training wisteria to grow on a pergola or arbor. These constructions must be fashioned of a sturdy, weather-resistant material, such as cedar, and properly anchored in the ground with concrete footings in order to be used effectively. Don’t be scared to overbuild a pergola or arbor because wisteria is notorious for tearing down its supports. I suggest using at least 24 lumber for the crosspieces and 44 lumber for the posts.
Allow two or three young shoots to knot loosely around each other and the post as they grow to start training a new plant onto a pergola or arbor. Since the woody stems grow gnarled and attractive as they mature, this will help give interest to the plant’s structure. As they climb, the young shoots need to be fastened to the post. To do this, fasten a 14-gauge galvanized (or comparable) wire to the post using eye hooks spaced roughly 18 inches apart (or on all four sides for extra support). Use gardening twine to secure the shoots to the wire as they develop. As they develop, give them some breathing room to develop a more attractive habit and avoid having them mature and put a lot of stress on the framework.
The shoots should be headed back (their tips should be pruned) once they have reached the top of the arbor to encourage side shoots that will spread across the tops of the supports and bear flowers. The training ties on the post will no longer be required as the plant matures and becomes more stable across the top of the structure. In order to keep the plant from becoming girdled as it grows, it is a good idea to remove them.