Is Wisteria Invasive?

Aug 18, 2024

Wisterias symbolize romance and beauty in most cultures. However, there is a rumor that wisteria is invasive. Is wisteria invasive? Yes, wisteria can be invasive, particularly in specific regions and climates.

Those varieties are invasive for their vigorous growth and ability to spread rapidly. This article will discuss those varieties and also those varieties which are not invasive. Let’s take a look.

Is Wisteria Invasive?

Wisteria has amazed gardeners for generations with its charming series of pink, purple, or white flowers. But behind its magical beauty lies a question that has sparked debate among gardeners and ecologists alike: Is wisteria an invasive plant?

Wisteria is a genus of blooming plants that includes several species. Which Wisteria is invasive? Notably Japanese wisteria and Chinese wisteria.

Both of these wisteria species are invasive. They are native to Japan and China. They were brought to the United States in the early 1800s as gardening plants. Both are considered invasive in some parts of the United States and elsewhere.

These days, wisteria is a widespread species in the US. These climbing vines are known for their remarkable flower displays and dynamic growth. However, their very dynamic growth can be a reason for concern.

Their ability to spread quickly with hardiness allows them to thrive in various soils and conditions. It makes them a threat to native plants. Wisteria can grow so vigorously that it can strangle trees, engulf structures, and invade natural habitats.

The Environmental Impact of Invasive Wisteria

Now the question is: how invasive is wisteria? What are the environmental impacts of invasive wisteria? The environmental impact of invasive wisteria species can be massive and damage ecosystems.

Invasive wisteria species, especially Japanese and Chinese wisteria, are known for their aggressive growth. When they escape cultivation, they can cause several environmental problems.

Here are some of the notable effects of wisteria that denote how wisteria is invasive.

Surpassing Native Plants

Wisteria can form dense thickets and climb over other plants. It can quickly outcompete native plants, trees, and shrubs. This maximizes the competition for water, sunlight, and nutrients and reduces native plant populations.

This way, it can reduce biodiversity. Also, it shades out and strangles native vegetation. Wisteria can twine around their branches, cutting off the bark and killing the plant.

Increased Sunlight

When wisteria vines uproot large trees, they create gaps in the canopy. It allows more sunlight to reach the forest floor. This encourages the growth of wisteria seedlings and other colonizing species.

Disrupting the Habitants

In addition to displacing native plants, wisteria also disrupts the habitat of several wildlife species. Those species depend on native plants for food, shelter, and breeding grounds.

Girdling and Choking Trees

Invasive wisteria wraps tightly around tree branches, which is called girdling. Over time, this can limit the plant’s ability to deliver water and nutrients. This eventually leads to the death of the plant.

Increased Risk of Falling Trees

Wisteria weight tends to increase over time. This added weight can weaken trees. This gradually makes them more susceptible to collapse during storms or high winds. It can further disrupt the surrounding ecosystem.

Changing Soil Structure

Wisteria has a dense root system, which can change the soil structure. It makes it difficult for other plants to establish themselves. Also, it can affect the local ecosystems in the long term.

How to Identify Invasive Wisteria in Your Garden?

So, how do you determine which wisteria is invasive in your garden? You can manage the spread of wisteria and protect your local ecosystem by identifying invasive wisteria. Here are some signs you can look into the wisteria in your garden.

If you notice any of these symptoms on wisteria leaves, you probably have an invasive one. These are –

1. Look into Seed Pods

Invasive wisteria produces long, bean-like seed pods after flowering. Invasive wisteria spreads by these seed pods. They can be 4 to 6 inches long. They are greenish-brown when young.

They turn golden brown as they mature. These seed pods can split and release the seeds. It can shoot several feet around the plant. Later, it contributes to the spread of plants over a wide area.

2. Examine the Leaves

Wisteria leaves usually consist of a central stem with multiple leaflets. Both Japanese and Chinese wisteria have 7 to 13 leaflets per leaf. Also, the leaflets are over-shaped with smooth edges and pointed tips.

The leaflet’s size can be from 1 to 4 inches long. Besides, the leaves may have a somewhat glossy appearance. They are bright green when they first appear in Spring. Gradually, they become darker through the summer.

3. Check the Flowers

Wisteria flowers typically form striking, cascading clusters that can range from 6 inches to over a foot in length. The smell of wisteria is often as enchanting as its appearance, with some varieties exuding a sweet fragrance that complements their beauty. Invasive wisteria may produce flowers in lavender to bluish-purple hues, while other varieties showcase white or pink blooms.

Chinese wisteria often blooms in late spring before the leaves fully emerge. On the other hand, the Japanese one blooms a bit later after the leaves appear. You should take a note when they are blooming.

4. Check the Vines

A key difference between Japanese and Chinese wisteria is their twining vine direction. Japanese wisteria vines twist right to left (clockwise), while Chinese wisteria vines twist left to right (counterclockwise).

Looking at the direction of vines, you can decide whether it’s invasive or not. Moreover, wisteria vines become pretty thick and woody with time. Older branches can be several inches in diameter and become rugged over time.

Also, the vines grow rapidly. They can reach up to 10-30 feet or longer. The vines grow so long that they can climb trees, fences, and other structures. They can cover anything and make it grey.

5. Observe Growth Habits

Certain varieties of wisteria are called invasive due to their aggressive growth. They are more aggressive than native wisteria. They can spread through underground roots.

This results in new shoots developing some distance from the original plant. Moreover, invasive wisteria grows so vigorously that it can damage nearby structures.

Effective Strategies for Controlling Invasive Wisteria

Controlling invasive wisteria can be challenging but not impossible. There are two ways you can control invasive wisteria: chemically and manually. Let’s shade lights into these methods.

Chemical Control

Cut-Stump Treatment

Cut-stump is an effective treatment to control invasive wisteria growth. Apply a concentrated herbicide (a 25% solution of glyphosate or triclopyr in water) to the cut surface of the stem immediately after cutting the wisteria vine.

This method is most effective on large vines with a larger surface area. Also, this method can be used efficiently during the second half of the growing season (late summer and early fall).

Foliar Spraying

Foliar spraying is most effective on Chinese wisteria. Also, this method can be used in areas where cut-stump treatment would be impossible. It works mostly for smaller infections. Spray the foliage with a diluted herbicide solution.

Herbicide Application

Apply a systemic herbicide (such as glyphosate or triclopyr) directly to the cut stems and leaves of wisteria. The plant absorbs the herbicides and transports them to the roots. Gradually, it kills the entire plant.

Manual Control

Cut back wisteria vines regularly at the soil level. Cut them several times during the growing season to weaken the plant over time. Dig up as much of the root system as possible after harvesting the vine. Also, you can girdle the vine by cutting a ring around the circumference of the stem.

Alternatives to Invasive Wisteria Species

So, is there a non-invasive wisteria? Yes. There are several native, beautiful alternatives to invasive wisteria. They offer similar aesthetic appeal without the environmental risks. So, which wisteria is not invasive?

Here are some non-invasive alternatives to invasive wisteria.

American Wisteria (Wisteria frutescens)
Kentucky Wisteria (Wisteria macrostachya)
Climbing Hydrangea (Hydrangea anomala petiolaris)
Trumpet honeysuckle (Lonicera sempervirens)
Trumpet creeper (Campsis radicans)
Dutchman’s pipevine (Aristolochia macrophylla)

Real-World Examples: The Impact of Invasive Wisteria

Asian wisteria species, particularly Japanese and Chinese wisteria, significantly impact ecosystems and human-made environments. Here are some real-world examples showing the consequences of invasive wisteria.

Invasive wisteria has spread widely in forests and natural areas in the southeastern United States. This results in the loss of native plants, which affects the entire ecosystem.
In urban areas in the Mid-Atlantic States, wisteria causes significant damage to buildings, trees, fences and other structures. Property owners often have to face costly repairs due to this damage.
Public parks and botanical gardens often have to invest significant resources to manage and control invasive wisteria.
In parts of Tennessee, invasive wisteria threatens Tennessee’s yellow-eyed grass habitat.
In Southeastern forests, the dense mats of wisteria vines can change the natural fire regimes.

Final Thoughts

Thus far, you have learned “Is wisteria invasive?”. Wisteria is undoubtedly cherished for its stunningly beautiful flowers and ability to add aesthetic charm to any garden or landscape. It is also essential to know which wisteria is invasive.

Asian varieties are mostly invasive. They can pose substantial risks to local ecosystems by outcompeting native plants and damaging structures with their vigorous growth. Thankfully, now you know how to stop them from having further impact on the environment.

FAQs

1. Is wisteria invasive in the US?

Chinese and Japanese wisteria has been reported as the most invasive in at least 19 states in the US. They are founded mostly in the eastern US.

2. Is American wisteria invasive?

No, American wisteria (Wisteria frutescens) is not invasive. In fact, it can be a native alternative to invasive wisteria.

3. Does wisteria have invasive roots?

Yes, wisteria has invasive roots, particularly in Japanese and Chinese wisteria. The root system of these species is large and powerful. They can dig deep and spread wide around.