Invasive plants: Where does one gardener begin?
A Vermont gardener decides what she can do about invasive or potentially invasive plants in her state.
Eurasian bush honeysuckles, as the USDA’s Forest Invasive Plants Resource Center puts it, “are difficult to tell apart, even in the field.” That’s spot on, and I’ll have to wait until spring to tell if the bushes that grow on my land are Tatarian honeysuckle (Lonicera tatarica) or Morrow's Honeysuckle (Lonicera morrowii) or bella, or showy fly, honeysuckle (Lonicera x bella), or a mix of the three.
Whatever the species, all are invasive, botanical bullies that displace native plants and negatively affect native wildlife. Like other states, Vermont, where I live, maintains a list of plants that are flora non grata, species that are illegal to import, sell, or distribute. The list includes trees, shrubs, vines, aquatics, grasses, and herbaceous plants but are grouped together under the term “noxious weeds.”
Bush honeysuckles are on many states’ noxious-weed list, right up there with purple loosestrife (Lythrum salicaria), Japanese knotweed (Polygonum cuspidatum), and the tree that grows in Brooklyn, Ailanthus altissima.
Invasiveness is site specific (what's invasive in California isn't necessarily in Virginia), but these plants and a few others are considered noxious weeds pretty much everywhere.
Potentially invasive plants
Last year, Vermont’s Invasive Exotic Plant Committee went beyond the state’s official noxious-weed list and established a watch list of other potentially invasive non-native, or exotic, plants. The watch list includes some familiar and popular names, such as Norway maple (Acer platanoides) and Japanese barberry (Berberis thunbergii).
If the state accepts VIEPC’s recommendations, it won’t mean that gardeners will have to cut down their Norway maples or rip out their barberry hedges, but it will mean that commercial trade in these plants will be illegal.
Until that happens, VIEPC and Greenworks, the Vermont Nursery and Landscape Association, have created a Voluntary Code of Conduct for Vermont nurseries, landscape designers, and landscapers. More than 50 individuals and firms have signed on, agreeing not to sell or use Norway maple, Japanese barberry, common barberry (Berberis vulgaris), burning bush (Euonymus alatus; see first photo above), Amur maple (Acer ginnala), and yellow iris (Iris pseudacorus), as well as any cultivars of these species.
My small part in reining in invasives includes buying only from nurseries that have signed the Greenworks Code -- and conducting an all-out war on shrub honeysuckles, and common buckthorn (Thamnus cathartica; see photo at left). There are enough plants to keep me busy for years, so I try to remember that “The journey of a thousand miles begins with one step.”
Or, in this case, the extermination of a thousand buckthorns and honeysuckles begins with one shrub.
Karan Davis Cutler blogs regularly at Diggin’ It. To read more, click here. She's a former magazine editor and newspaper columnist and the author of scores of garden articles and more than a dozen books, including “Burpee -- The Complete Flower Gardener” and “Herb Gardening for Dummies.” Karan now struggles to garden in the unyieldingly dense clay of Addison County, Vt., on the shore of Lake Champlain, where she is working on a book about gardening to attract birds and other wildlife