The Green Invasion
Invasive plant species threaten to take over the county’s spaces, endangering birds, bees and butterflies. But homeowners can fight back by incorporating native plants in their gardens.
There’s a beautiful invader stalking the Hackensack River Greenway, a lush tract of land running along the river’s edge for 3.5 miles through the township of Teaneck. Its name is multiflora rose, and its gracefully arching branches bear delicate white blossoms in late spring, followed by seeds that spread profusely, allowing it to crowd out the native plants that have populated the woods and meadows of Bergen County for hundreds, if not thousands, of years. Its spread isn’t limited to the Greenway, and it’s far from the only alien invader plaguing the county.
Other interlopers include plants you’ve likely seen, even if you don’t know their names, among them Japanese knotweed, a bushy groundcover that leafs out earlier in spring than most native plants and thereby robs them of light and air; Canadian thistle, whose pretty purple flowers belie the tough underground root system that makes it frustratingly difficult to remove; and Japanese honeysuckle, a rapidly spreading vine that threatens native trees and shrubs, sometimes crushing them with its weight.
Invasive plants—defined as nonnative plants whose spread poses a danger to the environment—have made themselves at home in nearly every expanse of open land in the county: in parks and wooded areas, along rivers and streams, and in and around lakes and ponds. “Bergen County and the area surrounding New York City are very heavily invaded with many species,” says Linda Rohleder, director of land stewardship for the New York–New Jersey Trail Conference, headquartered in Mahwah. She attributes that, in part, to our diverse population and our immigrant forebears, many of whom wanted to grow a little bit of home in their new backyards. We prize our gardens and the expats that inhabit them, from Norway maples to Korean dogwoods.
On their home turf, invasive plants are just plants; they become invasive when we take them out of the niche in which they evolved and introduce them into areas where they have a survival advantage. “Different species have different mechanisms that allow them to outcompete native plants,” says Rohleder. “They grow quickly, or reproduce quickly, or better tolerate stresses like deer or pollution or trampling or temperature changes or drought.” Or, like many invasives, they face fewer challenges in their new homes. “By taking a plant out of where it evolved,” Rohleder explains, “you’re taking it away from the controls that kept its population in check, whether pathogens, pests or competition from other species.”
Not all nonnative plants are invasive, but all pose potential problems for our ecosystem. “Nonnative plants,” says Elaine Silverstein, a horticulturist and leader of the Bergen/Passaic chapter of the Native Plant Society of New Jersey, “don’t support the insects that are the basis of the food chain,” including beneficial pollinators such as bees, moths and butterflies. Conversely, notes Don Torino, president of the Bergen County Audubon Society, “native plants are the foundation of any wildlife habitat.” Consider the millions of migratory birds that make their way up from Central and South America in spring. “They’re looking for food,” says Torino, “and if they stop in an area that’s full of invasive plants, it’s basically a wasteland for them.” He compares the situation to walking into a supermarket and finding that all the produce is plastic.
The problem appears to be getting worse, thanks to increasing globalization and what Rohleder calls “the quicker movement of plants and animals around the world.” Climate change is playing a role as well. “As we change the climate, we make it suitable for invasives from warmer climates to migrate northward,” says Joel Flagler, agriculture agent for the Rutgers Cooperative Extension of Bergen County. As a prime example, he cites kudzu vine, that invasive scourge of the Southern states that’s increasingly finding a home in the Mid-Atlantic region.
But as the problem has grown, so has the response. Organizations such as the Native Plant Society of New Jersey and the National Audubon Society offer educational programs and online advice on mitigating invasives and encouraging the planting of natives. And a decade ago, the New York–New Jersey Trail Conference formed the Invasives Strike Force to survey and remove invasive plants from public lands in northern New Jersey and areas of lower New York State. Volunteer members of the strike force have gone into virtually every area of Bergen containing trails—including the Celery Farm in Allendale, the Flat Rock Brook Nature Center in Englewood, Rockleigh Woods Sanctuary and the Palisades Interstate Park—to determine which invasives have taken root, where and to what extent.
Armed with that knowledge, they then work to uproot them. Recently, the group has enlisted the aid of service dogs trained to sniff out invasives. And for the past year, volunteers have been collecting seeds from native plants and cultivating them for replanting.
As critical as their work is to addressing the problem, the average homeowner can play an equally important role. Torino notes that “there are a lot of scientists who believe the only way we’re going to save migratory birds”—whose numbers in the U.S. have dropped by 30 percent since 1970—“is to change the way we garden.” He’s talking about incorporating native plants, which attract the insects that are an essential food source for many avian species and which also offer fruits, nuts and seeds that co-evolved with the birds to provide the perfect food at the perfect time. Spicebush, for example, is a native shrub that develops large red berries just before the fall migration, allowing birds to fatten up for the demanding flight ahead. (Spicebush has other attractive traits, including its appealing fragrance and lacy yellow flowers and the fact that it’s a magnet for swallowtail butterflies.)
You can start small, suggests Silverstein, incorporating a few natives and adding more as the need arises. If you’re having trouble growing grass under a large shade tree, she says, “mulch around it and plant some shade-loving natives in the mulch— you’ll have a beautiful bed where you formerly had ugly lawn that was driving you nuts.” If your garden includes a few square feet in a sunny location, she suggests planting one aster, one milkweed and one native grass, like Indian grass or blue grama. “You’ll have a butterfly magnet and flowers from May to October,” she says. Silverstein’s recommendations aren’t just professional; they’re also personal. Her own garden in Ridgewood is filled with native plants, including two of her favorites: golden groundsel and New Jersey tea. The former will spread to become a striking groundcover, with evergreen leaves and daisy-like yellow flowers in spring. The latter is a small shrub whose tiny white June-blooming flowers attract swarms of diminutive pollinators.
One advantage of using native plants in the garden is, in fact, the bounty of birds and pollinators they attract. A native oak tree, for instance, supports more than 500 species of moths and butterflies, making it a beacon for the birds that feast on them. In comparison, the nonnative Bradford pear, whose white spring flowers have made it a favorite on city and suburban sidewalks as well as in private landscapes, supports not a single species. And that pear, which was originally considered noninvasive, is now finding its way into woodlands and other wild places. Ridgewood resident Anne Wolf has been growing native plants in her garden for the past decade. She’s entranced by the summer-long show the pollinators put on for her, attracted by such plants as native strawberry, thoroughwort and goldenrod. But even more, she’s heartened by the difference she’s been able to make in the health of the local environment, simply by choosing the right plants. “As I began to realize that I could be helpful to wildlife while I was having fun gardening,” she says, “I started putting in a lot more native plants.”
It’s easy enough to figure out which natives you’d like to incorporate into your garden. The Native Plant Society of New Jersey, for instance, offers lists of recommended natives, broken down by garden requirements and uses, such as plants for deep shade, semishade, sun, wet areas, plants for pollinators and deer-resistant plants. (See “Garden Smart With Native Plants” below for a selection of online resources.)
The greatest challenge to would-be native gardeners is finding the plants themselves. “If you walk into most garden centers,” says Silverstein, “you’re not going to find many native plants.” That’s beginning to change, slowly. You can find some native plants at Goffle Brook Farm in Ridgewood, Waterford Gardens (for water gardens) in Saddle River and Rohsler’s Allendale Nursery. You can also order them online from outlets like Toadshade Wildflower Farm and IzelPlants.
You don’t need a vast garden to make a significant difference. Torino’s personal garden is a 12-by-50-foot patch of land in an industrial area of the Meadowlands. And yet it supports some 20 butterfly species and more than 60 species of birds, including an abundance of hummingbirds. “You put in those native plants,” he says, “and it’s like turning on a light in a dark room.” The threat to native plants—and by extension, to native wildlife—is serious, but for home gardeners, the solution can be joyful. “We have to change the way we garden, the way we think about wildlife and how it’s all connected,” Torino says. “And then we can create these magical places right in our own backyard.”
Garden Smart with Native Plants
To determine which natives to incorporate in your garden, consult the following online resources:
- The Native Plant Society of New Jersey (click on “Native Plants”; the site also includes a list of invasive plants at npsnj.org/articles/invasive_plant_species)
- National Audubon Society (plug in your ZIP code)
- Jersey-Friendly Yards (click on “Jersey-Friendly Plants”)
By Leslie Garisto Pfaff