Invasive plants are a menace. Here’s how to avoid them in your garden.

If you walk through your yard, what do you see? Are there vines dripping with long clusters of light purple flowers?

Are there yellow or white snapdragon-like flowers sprouting from the ground?

What about a towering tree covered in dainty white blossoms during the spring?

These common ornamental plants might be pretty additions to your home landscaping, but they are invasive — nonnative plants that can aggressively spread into the natural environment and harm other species.

Still, you can find these plants in many nurseries, garden centers and online retailers in the United States. A 2021 study conducted by researchers at the University of Massachusetts Amherst found that 1,330 vendors in the Lower 48 states offered hundreds of invasives as ornamental garden plants, including 20 species that are illegal to grow or sell nationwide.

“People think, ‘Green is green, what’s the problem?’” said Alex Dencker, a horticulturalist at the Smithsonian Institution. “People need to know the damage that invasives do. … All green plants should not be created equal.”

Here’s what you need to know to avoid buying invasive plants and how to manage them if you have them already.

Invasives vs. nonnatives

Not all nonnative plants are invasive, Dencker and other experts said. There are many nonnative plants that don’t wreak havoc on the surrounding environment. But when invasive plants are introduced to areas where they didn’t evolve and don’t have any natural checks and balances in place, they will outcompete native species. Diverse forests and grasslands can be transformed into monocultures, ruining the soil and eliminating critical habitats for native insects and wildlife.

“Plants are the foundation of the food web,” said David Mizejewski, a naturalist at the National Wildlife Federation. “If you want healthy wildlife populations, you need healthy plant populations and we know that native plants and native wildlife species in any ecosystem are absolutely intertwined. You can’t have one without the other.”

It can be easy for an invasive plant in your yard to escape to your neighbors or into open land.

In many cases, it starts with a nursery plant. In a study published last year, researchers identified nearly 90 invasive plants species sold at more than 600 nurseries across the country. They found over half of the species taking root and spreading in areas within 13 miles of those nurseries - the median distance people in the U.S. travel to buy landscaping plants.

How to avoid invasives at the nursery

Before you go plant shopping, familiarize yourself with the species that are invasive to your area. Beyond looking at official lists available online, call experts with your local university’s extension program or contact your area’s invasive species group.

Once at the store, pay attention to a plant’s characteristics. Be wary if you see anything advertised as “self-sowing,” meaning it will spread its own seeds, “low maintenance,” or “fast growing,” Mizejewski said. But remember that not all plants with these features, which are highly sought after by many gardeners, are invasive.

One way to really be sure that you don’t buy an invasive is to choose native plants, experts said. There are likely native alternatives to invasive plants that will do the same job in your landscape. There are also lists of native plants online, based on region.

“At the same time as doing that job, [native plants] are also supporting wildlife because they’ve co-evolved with the birds and with the butterflies and with the bees and other pollinators and the kinds of wildlife that could actually coexist with us that are rapidly disappearing right before our eyes,” Mizejewski said.

Rooting out invasives

If you think you have invasive plants in your yard or garden, the first step is to identify them. Experts recommend using free plant identification apps that are managed by scientists, such as iNaturalist and Pl@ntNet.

If you find them, remove them before they start flowering or seeding, said Susan Carpenter, native plant garden curator at the University of Wisconsin-Madison Arboretum. Native plants should be your first choice to replace invasives, but you can also opt for noninvasive ornamentals, Carpenter said.

Be mindful of composting any plants you remove that have rhizome roots or seeds, which could end up back in your yard.

If you can’t remove invasive plants, there are ways to reduce their chances of spreading. For fruiting plants, you can remove the fruit, said Rebekah Wallace, EDDMapS coordinator and Bugwood images coordinator at the University of Georgia’s Center for Invasive Species and Ecosystem Health.

“In some cases, it’s do the best you can,” Wallace said.