Identify Invasive Plants in Gardens and Lawns: An invasive plant is any plant growing in places you don’t want it to and it grows so in a way making it quite difficult to control. An invasive plant doesn’t necessarily have to be a common garden weed and also remember that invasive species aren’t always ugly.
Remember that invasive plant species aren’t necessarily ugly and unattractive. Many were introduced because they were beautiful or because of their rapid growth and effectiveness as groundcovers. Identification of invasive species is further challenged by the fact that many plants that are invasive in some regions are completely well-behaved in other regions.
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How to Tell if a Plant Species is Invasive?
A lot depends on the garden that we are looking at. Bittersweet vines, for example, may look extremely attractive and desirable in some situations, but if they start dominating over your home garden, they can be quite a problem. And other plants, like the obedient plant (Physostegia), begin as perfectly attractive landscape species that you intentionally plant, only to prove their invasive character after a few months when you realize their uncontrolled growth qualities.
Some of the invasive species on the list are extremely attractive to look at. Consider the flaming bush (Euonymus alatus), an exotic (or “foreign”) plant native to Asia. Few bushes put on a greater fall leaf show than this one. The vine, delicious autumn clematis, is another fall standout (Clematis terniflora). Scotch broom is a summertime favorite (Cytisus scoparius).
Most Common Invasive Plants Species in Gardens
Here is a list of the most commonly occurring invasive plants and weeds in lawns and gardens.
Purple loosestrife is an invasive weed that has taken over marshes, swamps, and wetlands. Many individuals who have no idea what the plant’s name is have seen it numerous times and commented on its beauty. In reality, it is a gorgeous plant, but when massed together, they propagate and grow rapidly.
Purple loosestrife is supposed to have arrived in North America in the early nineteenth century as its seeds in soil used for ballast in sailing ships. It is now present in almost every region of the United States, with the exception of Hawaii and Alaska. These plants colonize wetlands by producing thick root mats which suffocate native plants, thus reducing animal habitat.
The Japanese spirea is a tiny shrub that is endemic to Japan, Korea, as well as China. This invasive plant has naturalized most of the North American region. Its spread has grown so out of control in certain areas that it is deemed invasive, and many are questioning how to control its spread. Managing Japanese spirea and other techniques of spirea control rely on understanding how this plant spreads and propagates.
If you wanted to drive out weeds in your garden, you’d be thrilled to learn about English ivy, a strong, beautiful ground cover which tolerates shade. That exactly describes English ivy. But there’s a catch, English ivy is overly aggressive, earning it a position on the list of the worst invasive species. It can easily escape from landscape cultivation and therefore is recognized as a severe invader, particularly in the Pacific Northwest region of the USA.
There are three “bittersweets” species to be aware of: the Bittersweet Nightshade (Solanum dulcamara), the American bittersweet (Celastrus scandens), and the Oriental bittersweet (Celastrus orbiculatus). The Oriental bittersweet vine is certain to appear on most lists of the worst invasive plant species in North America. The other varieties can be invasive as well, although not as much as oriental bittersweet. American bittersweet has beautiful red or orange berries which are frequently used in ornamental arrangements.
Wisteria is similar to bittersweet in this regard: The gardener in North America must differentiate amongst the American wisteria vines (Wisteria frutescens) versus their Chinese equivalents (Wisteria sinensis var.). While both varieties of wisteria are vigorous plants, he Chinese wisteria is highly invasive down the USDA hardiness zone 4 regions.
Sweet Autumn Clematis
Sweet autumn clematis, like the previous three vines, is one of those “good-looking” species that may overpower a landscape. It is particularly troublesome in the East as well as lower Midwest. While this plant has a really lovely odor, it is the only thing it has going for it. Clematis paniculata is also known as sweet autumn clematis, however it is a less invasive vine native to New Zealand. You must use caution while dealing with Clematis terniflora.
Another beautiful, sweet-smelling plant which turns out to be a dangerous adversary is Japanese honeysuckle. This aggressive, fast-growing twining vine grows to 30 feet and has fragrant yellow blooms that bloom from June to October. It is utilized as ground cover when planted intentionally, although it is regarded as an exotic invasive species throughout the USA Midwest.
If you plant it in the garden, take special care to keep this plant in control, including vigorously pruning it back on a regular basis. When this plant escapes, its enormous weight can break tree limbs and destroy trees and shrubs by weighing them down with its thick vines.
Kudzu vine belongs to the pea family. For a long time, K udzu has been used as animal fodder. However, this Asian perennial vine is among the worst invasive plants of all time, and therefore is frequently referred to as “the vine which ate the South.” It is a massive issue in the Southern states of the USA.
Originally planted to provide shade to porches on Southern plantations, this plant soon expanded to adjacent area, where it now consumes virtually anything it comes into contact with. It thrives in both sun and shade and is severely invasive throughout the South, Southeast, as well as up and along the Atlantic coastline. A recent weed management attempt involves introducing goats into kudzu-infested regions and releasing them to graze their fill.
Another common ground cover that may become invasive is the mat-forming ajuga, commonly known as bugleweed. Because of its attractive purple flowers and capacity to suppress weeds, ajuga is frequently used as a ground cover in gloomy regions. However, as it starts to take over the garden or lawn, many homeowners learn to detest it. Ajuga is particularly troublesome in warmer and hotter regions where there is little to no winter frost each year.
Barberry bushes have attacked North America in two directions. Berberis thunbergii is from Far East Asia, while Berberis vulgaris is from Europe. These invasive plants are armed with thorns which have made them so valuable in many a hedge. Barberry thunbergii, sometimes known as the Japanese barberry, is really invasive that it has been placed on a list of critically invasive species throughout most of the Midwest, implying that it shouldn’t be planted at all!
Burning bush offers a beautiful sight in fall, with its crimson or pinkish-red foliage. The beautiful foliage is complemented by reddish-orange berries. So, why is the burning bush regarded as one of the most despised alien plants by gardeners? This shrub is regarded as severely invasive over most of the northern United States, from Maine through Minnesota, and in the Southeast.
Lantana is a broadleaf annual shrub native to the tropical regions that has become a significant invasive in Florida, Georgia, and California. However, it is not a threat in cooler areas north of zone 9, in which it is commonly used in hanging baskets in gardens. However, in warm climates, it may readily leave gardens and naturalise in hazardous numbers.
Butterfly bush is one of the most troublesome invasive plant in the Pacific Northwest region, where the growing conditions are similar to those found in its natural environment. It is also an invasive issue in the Southeast. It is less of an issue in regions colder than zone 6, because the plant dies down to ground level every winter. Butterfly weed (Asclepias tuberosa) is another plant that may be grown to attract butterflies. Butterfly bush is so named because it attracts butterflies and other pollinators, yet the plant has an unpleasant odor to humans.
Privets, just like the Barberry are a common sight and this familiarity might make it difficult for some people to write them off as invasive plants. But the fact that common privet is on the government’s list of most invasive plant species is something to think about. Privet is considered outright invasive in much of the USA Midwest and Northeast from Pennsylvania to Maine. Privet’s appeal comes from the fact that it can be trimmed well and can withstand the pollution that often afflicts plants in urban areas. However, because privet bushes grow so quickly, they may readily escape cultivation and become naturalized in the wild.
Japanese knotweed is a clustering perennial plant with little landscaping value. Probably the best that can be stated about its looks is that it blooms in early fall with a fluffy-looking blossom (thus its alternate name, the “fleece flower”). Regardless of the views of 19th-century plant collectors, many 21st-century Westerners agree on one thing: Japanese knotweed is an unsightly annoyance and an easy selection as one of the worst invasive species. It is regarded invasive in all states, but especially so in its native hardiness zones of 5 to 9.
Full-grown trees can also be invasive, as in the case of Norway maple, which is deemed invasive in most of the Northeast and potentially harmful in Maine, Vermont, New Hampshire, as well as Massachusetts. Initially introduced as landscape trees, its seeds are easily dispersed by wind and have naturalized in different habitats.
Unlike the other invasive plants mentioned in the above list, Tansy is a herb and it’s quite harmful. Tansy is a toxic herb but it has a long history of being used as a medicinal plant. Apart from being toxic, these Tansy plants are also highly invasive and can spread through their seeds as well as rhizomes.
Resources for Identifying Invasive Plant Species
Using your own gardening experience is one of the best ways to recognize common invasive garden plants. If you are unsure about recognizing an invasive species, take a photo and contact specialists at the local cooperative extension office to assist you.
You can also refer to the resources from,
- Invasive Plant Atlas of the United States
- EU Commission: Environment (in Europe)
- U.S. Department of Agriculture
- U.S. Forest Service
- Center for Invasive Species and Ecosystem Health
Experts may also be found in organizations like the Soil and Water Conservation, as well as Wildlife Departments, Forestry, and Agriculture Agencies. Most counties, particularly in agricultural areas, have weed control offices.