We all have at least one plant in our garden that threatens to take over. It spreads out like a carpet or pops up in random places all over the garden, and no matter how much time we dedicate to pulling it up, it still persists. In addition to how to get rid of it, we should be asking ourselves, Is this plant invasive? Is it spreading into wild areas and choking out native plants?
What is an invasive plant, anyway? This invasive plants guide provides a definition of invasive plants, explains what makes a species invasive, discusses the negative impacts of invasive plants, and offers suggestions for how to get rid of invasive plants. Scroll to the bottom to find a list of links to articles on invasive plants by state, so you can learn which plants are invasive in your area.
Invasive Plants Guide
What is an invasive plant species?
An invasive plant, according to Invasive.org, is a nonnative plant that causes or will likely cause harm to the environment, economic interests, or human health. A plant is labeled “invasive” when it becomes overly aggressive, growing and reproducing rapidly and significantly disturbing the area around it.
Not all exotic species are invasive. But while only a small percentage of nonnative species eventually become invasive, it is difficult to predict whether a species will become invasive when it is first introduced. Those that do earn the “invasive” label wreak havoc in many ways and are difficult to remove.
Why are invasive plants bad?
In the garden, you likely have observed an exceptionally aggressive plant take over a bed, possibly outcompeting other plants for space and resources. Where you once had a nice variety, you now have a dense population of one plant, perhaps peppered with a few sickly specimens of other species struggling to hang in there. When you try digging it out, you find it nearly impossible to remove every piece of living root, or it reseeds so readily that it pops back every year despite your best efforts.
You can begin to see why invasive plants are such a problem in the wild. When introduced to a new area, invasive plants lack the competitors, parasites, diseases, etc. that keep them in check in their natural habitat. As a result, these plants grow and spread unchecked, outcompeting and displacing native species. A once diverse patch of wildflowers becomes a carpet of a single invasive plant species.
Not only do invasive plants cause environmental harm, but they can also negatively impact agricultural crops, aquatic environments (and thus the fishing industry), and even human-made structures. Some invasive plants are toxic to livestock or people.
Threats to native wildlife
When an invasive plant species takes over an area, it outcompetes the native plants that provide food and habitat for native wildlife. It might even cause harm more directly by disrupting vital functions of the ecosystem like nutrient cycling, water flow, and soil decomposition.
Some invasive plants are toxic to wildlife, but since the plants are not native, the animals do not know they should avoid eating those plants.
How invasive species spread
Many invasive plant species are introduced intentionally, such as for ornamental or agricultural purposes. The people who initially introduce them do not realize that the plants will become invasive, but the plants eventually escape cultivation and spread in the wild. Other species may be introduced accidentally, such as when seeds “hitchhike” in freight or even on travelers’ clothing.
Depending on the type of plant, invasive plants spread in different ways. Some spread via rhizomes, and others through airborne seeds.
Birds eat the berries of fruiting invasive plants and deposit the seeds miles away. People, too, spread invasive plants, whether knowingly or not.
Some invasive species are still sold as ornamental garden plants, and well-intentioned gardeners thus plant a noxious weed in their garden.
What can gardeners do in curbing the spread?
As gardeners, we have the privilege and responsibility to steward plants, both native and introduced. While we thrill in watching an exotic plant thrive in our garden, we must take care that our hobby does not harm the world around us. How can we enjoy gardening without guilt? First, do no harm:
1. Avoid planting invasive species
When considering introducing a new plant to your garden, whether through a purchase or through cuttings or seeds from a friend, do a bit of research first. A quick search online will reveal whether the plant in question is considered invasive in your region. To make things even simpler, bookmark a list of invasive species in your state, such as the ones listed below or the handy map provided by the University of Georgia’s Center for Invasive Species and Ecosystem Health.
2. Remove invasive plants
This action is a bit more involved but hugely important. If you haven’t already, make a list of all the plants in your garden, then look up each one to see if it is considered invasive in your area. Alternatively, you might read through a list of invasive plants in your state and see if you have any of them in your garden. This might be a good activity for a rainy day or during the winter.
If you discover that you do have invasive plants, take steps to remove them. Depending on the specific plant, you might pull or dig it up or cut it down and paint the stump with herbicide. Particularly stubborn species can require multiple purgings before they finally stop popping up in your garden.
3. Choose native plants
While many introduced plants can be safely planted in your garden without aggressively spreading, the best options are native plants. Plants endemic to your region are well adapted to your growing conditions and thus will thrive in your garden with little care. They also provide food and habitat for native pollinators and other wildlife.
If you have discovered that a beloved plant is invasive, consider its qualities that you most appreciate and look for a similar native replacement. For example, American bittersweet might replace nandina with its crimson berries, or American wisteria the fragrant flowers and vining habit of Japanese wisteria.
Invasive plant disposal
A quick note on disposing of invasive plants that you remove from the garden: It is important to dispose of invasive plants properly, as doing so incorrectly can result in the plants spreading and undoing all of your hard work. Different species will have different removal and disposal methods, so make sure to do your research.
In general, though, most invasive plants should be burned or securely bagged and taken to the landfill. Those that only spread through seed may be composted if they are removed before they flower.
Invasive plants in Maryland
Invasive plants in Massachusetts
Invasive plants in Michigan
Invasive plants in Minnesota
Invasive plants in Mississippi
Invasive plants in Missouri
Invasive plants in Montana
Invasive plants in Nebraska
Invasive plants in Nevada
Invasive plants in New Hampshire
Invasive plants in New Jersey
Invasive plants in New Mexico
Invasive plants in New York
Invasive plants in North Carolina
Invasive plants in North Dakota
Invasive plants in Ohio
Invasive plants in Oklahoma
Invasive plants in Oregon
Invasive plants in Pennsylvania
Invasive plants in Rhode Island
Invasive plants in South Carolina
Invasive plants in South Dakota
Invasive plants in Tennessee
Invasive plants in Texas
Invasive plants in Utah
Invasive plants in Vermont
Invasive plants in Virginia
Invasive plants in Washington
Invasive plants in West Virginia
Invasive plants in Wisconsin
Invasive plants in Wyoming
Invasive plants are a major problem, posing major threats to native wildlife and ecosystems. But knowledge is power, and the first step toward eradicating noxious weeds is educating yourself and others. Learn about invasive plants in your state, identify any in your garden, and finally, take action to remove and replace invasive species with native plants.