17 Of The Worst Invasive Plants To Avoid At All Costs

I became a professional gardener because I love plants. But some plants can be very hard to love. Specifically, dealing with invasive plants can make my job difficult, unpleasant, and even potentially dangerous (especially when I encounter plants I am allergic to, like Oriental bittersweet). Some of my clients have invasive plants that were already on their properties when they moved in, while others have planted things that they didn't know were invasive at the time. I've compiled a list of some of the worst invasive plants I have dealt with, that you should avoid planting at all costs.

Some of the most invasive plants are vines, which can grow very quickly and climb high onto structures and trees. Most vines have a twining nature that can entangle structures (like fences or buildings), trees, or shrubs, causing serious damage over time. Some gardeners like to grow vining plants to create privacy, and there are some non-invasive vines that can create a cozy backyard oasis that won't cause the problems that invasive growers can. 

Removing invasive plants by the roots is the best technique for eradication; cutting them back only stimulates the root systems to grow stronger. While some plants with invasive tendencies can be controlled with frequent pruning or other techniques, it can be hard to eradicate invasive plants from your yard once the growth gets out of control. This can happen quickly if maintenance is not constant — some fast-growing invasive trees or vines can cover over a garden in one season if left to their own devices.

This plant is my worst enemy as a professional gardener. Why? Because it's not only super invasive, it emits a toxic sap that can cause severe allergic reactions, including an itchy rash similar to that caused by poison ivy. Oriental bittersweet (Celastrus orbiculatus) is a woody vine that produces colorful berries in autumn. I'm here to tell you, do not plant this. Ever. It is easily confused with the less-invasive "American bittersweet" (Celastrus scandens L.) sold in nurseries, but horticulture experts in Massachusetts believe the two species are hybridizing and the aggressive version is dominating.

I had a client who asked me to plant peppermint in her beds — that was the only plant she wanted there. I asked her to reconsider, because if she changed her mind, it would be difficult if not impossible to remove. Can you see where this story is going? Sigh. Most gardeners know to only plant peppermint (Mentha x piperita L.) in containers, but if you don't, here's a professional gardener telling you: You should never grow mint in the ground in your garden! It will take over and become a nightmare to get rid of. 

Though English ivy (Hedera helix) is loved for its deep green color and evergreen beauty, it's a fast and aggressive grower with a very invasive root system. Gardeners who think, "Oh, I'll just plant this and keep it trimmed and it won't spread" have lived to regret their decision to plant it. Though sometimes considered a ground cover, this vigorous ivy loves to climb trees and buildings, can cause structural damage to homes, fences, and brick walls over time. I've had clients who've tried unsuccessfully to eradicate it for years and it's determined to stay.

Sometimes called American bamboo due to its hollow, bamboo-like stems, Japanese knotweed is a plant native to East Asia that has become an invasive nuisance in North America. These fast-spreading deciduous shrubs crowd out other vegetation, disrupting ecosystems in woodlands and meadows. Japanese knotweed (Reynoutria japonica) also worsens urban blight when it spreads in vacant lots or city parks. Its aggressive root systems spread via rhizomes, and even a small piece of root can generate large patches of growth quickly, so it's crucial to remove them completely to control its spread.  

Native wild roses (Rosa blanda) have fragrant five-petaled flowers of pink or white, and produce abundant tiny rose hips that attract a diverse variety of birds in autumn. However, these fast-growing roses tend to grow very large, and can be invasive and hard to eradicate from the landscape. While they can be a good addition to a large wildflower meadow, improving biodiversity and providing shelter and food for wildlife, they're not really suitable for a small area or for a contained flower bed. 

Although loved for their vivid autumnal color, these deciduous shrubs reseed and spread invasively in North America. Also known as winged euonymus, the burning bush (Euonymus alatus) can be trimmed into a tree form, and there are dwarf cultivars available in nurseries. However, its tendency to spread in woodland areas has given it a reputation as a problematic invasive (spread by birds who eat the berries) that crowds out indigenous plant species. Consider replacing it with other shrubs that have colorful autumn foliage, such as common ninebark, pagoda dogwood, or American witch hazel. 

Wild grapevines grow fast, have a seemingly limitless spread (I've seen them scramble to the tops of fifty foot trees), and are difficult to eradicate. In areas where backyard grape arbors are common (like New York state), these were often planted as cheap alternatives to other grapes to provide shady patio coverage. But they can easily spread out and cover structures rapidly. It is imperative to keep them trimmed to stop them from entangling power lines. Use copper nails or horticultural vinegar on the cut roots to help weaken them so they can be dug out.

Though some homeowners like the brilliant autumn colors of Virginia creeper, this fast-spreading vine can be invasive and hard to eradicate once it takes hold. Birds eat the small berries, but they're toxic to humans. The roots of Virginia creeper (Parthenocissus quinquefolia) may spread into difficult spots such as foundations and cracks in stone walls. If you already have it on your property, keep it well-pruned. To kill the roots, try copper nails (if the woody stem is more than an inch in circumference), or paint the cut edge with horticultural vinegar and repeat as needed.

The small shoots of this invasive deciduous tree are easy to identify by their lance-shaped leaves, that grow large even on small saplings. The tree of heaven (Ailanthus altissima) is also sometimes called false sumac, and has a pungent odor when pulled or cut. These must be pulled out by the roots. If they're cut or weed-whacked, the roots will grow larger and form an unruly underground web that will spread throughout your lawn or beds and become nearly impossible to get rid of. Ask me how I know. Avoid planting this one!

Though some admire the colorful spiky flowers of purple loosestrife, it has caused many a gardener to regret digging up a roadside plant to add to their garden. The root system of this plant is very vigorous and difficult to remove once established. Purple loosestrife (Lythrum salicaria) has become a danger to wetland ecosystems throughout the Northeast U.S., where it has invaded aggressively by reseeding rapidly. Though it likes to grow in moist areas, it can reseed itself almost anywhere, so keep an eye out and remove it from your garden if it appears.

This floriferous, late-blooming clematis is popular for its abundant white, fragrant flowers. While the vines can be trimmed to control size and spread, this plant has an unfortunate tendency to reseed itself. It can be very invasive in the garden, where new plants tend to wrap around the base of perennials, or in woodland areas, where the vines may strangle shrubs that birds rely on for food. Once a common clematis choice, planting sweet autumn clematis (Clematis terniflora) is now discouraged due to its invasive tendencies.

The variegated version of wintercreeper (Euonymus fortunei), also called fortune's spindle, is often admired in nurseries where it is purchased in containers, looking like a small shrub. However, it actually has a vine-like growth habit. Planted by a fence or trellis, it's an attractive evergreen plant, but in flower beds it tends to spread aggressively. The thick, woody roots are also hard to remove. Plant this one where it has a sturdy structure to climb on and keep it trimmed. Don't plant it in beds, where it will crowd out other plants.

Also called gout weed or ground elder, Bishop's weed (Aegopodium podagraria) is a leafy perennial ground cover with tiny white flowers. It also comes in a variegated variety, sometimes called "snow-in-summer" and grown for its attractive foliage. I've had plenty of experience with this one, and it is one of the most annoying invasives I've encountered! The small white roots are easy to see when digging, but if you don't get every bit of the roots, they will continue to grow and spread, crowding into sidewalk and foundation cracks.

Creeping jenny (Lysimachia nummularia) is often included in container arrangements. Well-meaning gardeners who like its lime-green tendrils transplant it to their flower beds, only to find that it spreads agressively throughout the garden. The root system of creeping jenny is fairly shallow and not too tough to pull out, but it can take some time and effort to get rid of it. I've been able to remove it from beds by pulling out clumps and combing with a fork tool to remove the tiny roots. Then, I continue to remove any stray shoots that pop up.

I love the incomparably lovely scent of these spring blooming flowers, and often cut a few for vases in my home when I see them. However, this plant is a real no-no for flower beds, where it will spread and strangle out other plants. The tiny fragrant flowers of lily of the valley (Convallaria majalis) are the source for a famous perfume (Muguets des bois). This plant can make a good ground cover for shade in an out of the way spot, or a woodland area where it won't interfere with other perennials.

The tawny day lily is a popular perennial often seen growing by roadsides. Also known as ditch lilies or native day lilies, tawny day lilies (Hemerocallis fulva) are often confused with the non-invasive species of day lilies (Hemerocallis spp.) that come in a wide range of colors. Though it's a reliable bloomer, it spreads aggressively via long roots and also reseeds itself. It can be hard to get rid of and tends to rob nutrients from garden soil. Put this one in hard-to-fill spots like driveway edges, and keep it out of your flower beds.

This is one of those plants that has some desirable qualities, and yet is still horribly invasive. Trumpet vine (Campsis radicans) has lovely trumpet-shaped flowers in coral red or bright yellow that attract hummingbirds. But this fast-growing vine not only gets very long and can entangle shrubs, trees, and structures, it also reseeds itself very aggressively and is very hard to eradicate from the garden. Definitely avoid planting this one, especially if you live near woodlands, where it can damage trees and undergrowth.