Another Way to Look at "Invasive" Plants
Question. I have a three-acre property; some lawn and a lot of "meadow" that I mow every fall. When we first bought the property, which is close to a creek, the fields were filled with daisies and other varieties of wildflowers. Now, 15 years later, it is increasingly filled with mugwort, dogbane and multiflora rose. I called my local extension service garden hotline and they recommended spraying with Roundup. I certainly don't want to do that, especially considering the nearby creek. Any other ideas?
- ---Linda in Pennington, NJ
Answer. Well, first I have to deliver a kick in the pants to the so-called experts who doled out that foolish advice. If New Jersey's 'book' really says to spray Roundup or any other chemical herbicide in or near an aquatic environment, 'The Garden State' would be better off without an extension service.
- Chemical herbicides like Roundup (make that specifically Roundup) are death on a stick to frogs, toads, salamanders and other amphibians (see the excellent work of Dr. Rick Relyea at the University of Pittsburgh for the disturbing details).
- The two most common herbicides in use today are human hormonal disruptors, and the most troubling modern human cancers are hormonally influenced. Cause and effect? Coincidence? I'd rather not find out, thank you. If you choose to spray anyway, be aware that you're playing 'you bet your life.'
Bottom line: No chemical herbicide is even remotely safe for people and the environment, and the current and unfortunate tendency to spray first and ask questions later (if ever) must be changed if we want to seriously lower the cancer rate and reverse our degradation of the environment.
Now: if any of these so-called 'weeds' are in your lawn, the problem lies with your lawn care and not the unwanted plants. Presuming it isn't zoysia grass (whose care is very different), an East Coast lawn should be fed twice a year; in Spring and Fall—never in the summer. Summer feeding of cool-season grasses weakens the grasses and feeds the weeds. A cool-season lawn should never be cut lower than three inches; low cuts kill the grass and encourage weeds. And any watering should always be in the form of a long, deep, infrequent drenching. Short daily waterings maximize the amount of non-grass plants in a lawn.
Now, as to your specific problem plants:
"Mugwort", a more common weed of urban than rural areas, thrives in salty, compacted soils with a high pH; conditions that are all absolute death to lawn grasses. Have your soil tested and bring the pH down to normal if it is alkaline; aerate the turf this Fall; and don't use rock salt in the winter. If nearby roads are heavily salted, you are simply [bad word] out of luck; road salt kills wanted plants and makes mugwort hale and happy.
"Dogbane", also known as Indian hemp, black hemp and American hemp is, as two of those names imply, a native plant. It provides food for pollinators and other beneficial insects and was an important source of fiber for Native Americans, with an average plant yielding two feet of waterproof, stretch-proof fiber with twice the tensile strength of cotton. The highly prized fibers are still used by modern craftspeople, and the website that told me all this cool stuff has a link to folks who harvest and sell it. Perhaps you can go into the hemp business.
Multiflora rose is, like many now-unwanted plants, a deliberate import that was heavily promoted for agricultural use as a 'living fence' and erosion controller. My woods are full of it, and this season it bloomed like mad, making me a liar for saying so often that the flowers are unattractive because they looked sensational. And they so heavily scented the air with a wonderful fragrance that my wife asked me what smelled so good. "A bad plant", I told her. "Really?" she responded, "we need more of those." Multiflora rose provides essential cover for birds and other wildlife, and copious food for wildlife and people via its super-nutritious rose hips (an excellent natural source of vitamin C). It is unsurpassed at erosion control.
Again, none of those three plants are known as lawn weeds. If they're in your lawn, it clearly hasn't been cared for. Consider the advice of Iowa State University turf grass expert Dr. Nick Christians: If your lawn is more than half weeds, till it all up, replant it this August and then care for it correctly. If it's more than half grass, pay more attention to correct lawn care and the grass will gradually vanquish the weeds. Direct assault of lawn weeds never works; the secret to a weed-free lawn is all in the lawn, never the weeds.
Ah, but Darwin and Mother Nature are in control that meadow. As Peter Del Tredici, Senior Research Scientist at the Arnold Arboretum of Harvard University explains in his excellent new book, "Wild Urban Plants of the Northeast", your unwanted plants are succeeding there naturally. (And perhaps because you are unnaturally mowing the meadow in the fall, which probably favors the 'bad' plants immensely.) It is possible to remove and replace such plants, notes Del Tredici, but not without tremendous environmental destruction and endless intensive care for the replacement plants. You can't just spray the "weeds" and have wanted plants suddenly thrive; the reworked area would have to tended like a garden. (But it would require much more work than a regular garden.)
The plants that are there now are stabilizing the soil, managing storm water, protecting the creek and watershed, and providing food and shelter for wildlife. Before you remove those plants, take a careful, objective look at the plants you propose installing in their place. If they won't do a better job, you'd just be trying to dominate Nature, not manage it.