Most invasive plants were originally introduced as ornamentals in the landscape. But as they naturalize at such a rapid rate, they have destroyed habitat and displaced native species throughout the Northeast. They pose an ever-evolving environmental challenge, with new species emerging and expanding their ranges as the climate changes and disruption of native habitats continues. It is important to become familiar with the invasive species common in your area and stay up to date on your state’s invasive species list so you can recognize and remove these pests when they appear on your property. It is perhaps even more important to review plants on your state’s watch list. These are plants that are not banned for sale but are locally invasive or have the potential to cause environmental problems. Staying informed about additions to this list will help gardeners stay ahead of the curve in preventing the spread of invasive species.
Below are some species that are on the watch list in many Northeastern states but are still commonly sold or clearly labeled as invasive. Gardeners tend to leave these species alone or plant them, so I have included native alternatives. These species behave in the same way as invasive species and can help preserve the environment rather than destroy it.
Invasive plants: Burning Bush (Winged Euonymus)
By October, it’s easy to see why burning bush was, and still is, sold in some states for its ornamental value. But it’s equally clear from the ocean of brilliant red and pink leaves lining the roadside that it’s a terrible invasive species, effectively smothering any native vegetation. In addition to avoiding it, gardeners should remove older specimens from their yards.
Alternatives to bush burning: Consider highbush blueberries (Vaccinium corymbosumZones 3–7) or native honeysuckle (Honeysuckle spp. and cvs., Zones 3–9) for beautiful fall color.
Invasive plants: Lady’s Rocket (Hesperis matronalis)
It’s hard not to admire grandma’s rocket plant when it blooms in a myriad of pinks and purples in late spring, but this beautiful phlox (Phlox paniculataZones 4–8) like this one are on the banned plant list in many states. I often see homeowners mowing the lawn around dame’s rocket to preserve it. I also see gardeners transplanting it into their gardens, mistaking it for phlox.
Alternative to Dame’s Missile: Since they look so similar, garden phlox is a perfect substitute.
Invasive plants: Valerian (Valeriana officinalis)
Valerian is a popular herbal plant for sleep and relaxation, but in recent years it has become an invasive problem in the Northeastern states and has been added to several banned plant lists. It remains a popular herbal addition to the garden but should be avoided due to its tendency to spread seeds extensively, both in the garden and beyond.
Substitute for valerian: For a native perennial that looks similar to valerian, try the common valerian cactus (Eupatorium perfoliataZones 4–8). If you are growing valerian as an herb rather than an ornamental, be sure to pull the plant before it flowers.
Invasive plants: Wine berries (Rubus phoenicolasius)
Wineberries are delicious! For this reason, I often encounter resistance when I advise homeowners to remove this shrub, but wineberries are very aggressive, fast-growing plants that spread both by stem and bird spread. They can be distinguished from other caneberries by their hairy red stems.
Substitute for strawberries: Wineberries often grow alongside our wild Northeast blackberries (western bushZones 3–7), are ideal native choices when one wants to preserve the mulberry.
Invasive plants: Le Callery (Pyrus calleryana)
This popular spring-flowering tree has begun to escape cultivation and has the potential to cause environmental havoc. Even without its invasive tendencies, it is not an ideal tree choice because it has a weak branching structure and branches that break easily in storms, disfiguring the tree. If your Callery tree has been damaged this winter, now is the perfect time to consider replacing it!
Alternatives to Callery pears: Native serviceberry (Amelanchier canadensisZones 4–8) and thornless hawthorn (Hawthorn chicken feet used to be. no weaponsZones 3–7) also have delicate white spring flowers. For other native alternatives to Callery pears, read here.
Invasive plants: Japanese Tamarind Tree (Berberis thunbergii)
Although many cultivars of this plant have been banned for sale, potentially invasive varieties are still common in our Northeast landscape. Gardeners should consider removing older varieties and replacing them with newer varieties that are marked as non-invasive or non-concerning.
Alternatives to Japanese Tamarind: Native shrubs such as Virginia sweetspire (Itea virginicaZones 5–9), New Jersey tea (American CeanothusZones 4–8), leucothoe (Leucothoe spp. and cvs., Zones 5–9), and ninebark (ConifersZones 3–7) are all great alternatives to Japanese tamarind.
Invasive plants: Japanese and Chinese Wisteria (Floribunda wisteria And Wisteria sinensis)
Japanese and Chinese Wisteria can strangle and shade even the largest trees. But unlike its vine invaders, bittersweet (Celastrus orbiculatus), they travel by means of a vast network of stems, making them potentially more difficult to eradicate. Despite their beauty, many gardeners regret growing these overly vigorous vines.
Alternatives to Japanese and Chinese wisteria: Native Southeast Wisteria, American Wisteria (Wisteria frutescensZones 5–9), is a good hardy alternative, as is our native honeysuckle (Lonicera sempervirensRegions 4–9).
To see a complete list of banned and watchlisted plants where you live, visit your state’s department of agriculture website. Some states invite the public to help identify problem plants, and you can report a non-native plant you see growing naturally in wild areas. Gardeners are in a unique position to observe potentially invasive plants, and there are also many ways to get involved in local efforts to remove and control these invasive populations. Contacting your local parks or forestry association is a good place to start, whether you want to help out on public lands or simply learn how to effectively identify and control your own pests.
To discuss these plants or ask gardening questions, chat with the author on the Gardening Answers forum.
Read on here for more recommendations on alternatives to invasive species.
For more Northeast region reports, click here.
Chloë Bowers is a landscape designer based in Newtown, Connecticut.
