Dear EarthTalk: I pruned back an overgrown bush in my back yard last fall and now the soil around it is covered in dandelions and other weeds. Is there any way to get rid of these weeds without resorting to RoundUp and other chemical herbicides?
— Max S., Seattle, Wash.Weeds are nothing if not opportunistic. While you may not have bargained for getting one form of eyesore (weeds) by clearing another (an overgrown bush), dandelions and other fast-growing, quickly spreading plants know no bounds when some new territory opens up. They will colonize and spread out given the slightest opening — after all, that’s what defines them as weeds.
Of course, conventional herbicides such as Monsanto’s RoundUp will take down the weeds in a jiffy, but the negative effects on people, animals and the environment may be both profound and long-lasting. Independent studies of RoundUp have implicated its primary ingredient, glyphosphate, as well as some of its “inert” ingredients, in liver damage, reproductive disorders and non-Hodgkin’s lymphoma, as well as in cardiovascular, gastrointestinal, nerve and respiratory damage.
California’s Department of Pesticide Regulation reports that, year after year, RoundUp is the number one cause of pesticide/herbicide-induced illness and injury around that state. RoundUp is also blamed for poisoning groundwater across the U.S. and beyond, as well as for contributing to a 70 percent decrease in amphibian biodiversity and a 90 percent decrease in tadpole numbers in regions where it is used heavily.
Given that you’ll have to manually remove dead weeds from your yard after applying RoundUp (or any other “post-emergent” herbicide), why not just pull them up by hand in the first place? No doubt, the most eco-friendly way to get rid of weeds is to yank them out without the aid of poisons. Unfortunately, many weeds have long, deep roots which need to be pulled completely if you don’t want them to grow back; if need be, use a metal weed puller with a hooked end or a mechanical grabber — available at any local garden supply or hardware store — if you don’t want to have to pull those very same weeds next year.
Garden expert Dean Novosat of the Garden Doctor website suggests giving the weed beds a good watering the night before you pull weeds: “… the soil will be softened and will yield the entire weed plant, root and all,” he says. Another way to kill weeds, he says, is by pouring boiling hot water over them.
Of course, once you’ve killed or pulled up all those weeds — and make sure you’re thorough or else it’s a waste of time — you’ll want to make sure new ones don’t start showing up in their place. Planting regionally appropriate (and ideally native) plants in place of the removed weeds would be a good first step — check with a local nursery about what some good choices might be for your neck of the woods.
Once the area is cleared (and replanted), cover it with three to six inches of mulch. Mulch forms a barrier between the soil and the sun, depriving any new germinating weeds of the sunlight they need to photosynthesize. Mulch is composed of large chunky material such as wood chips and bark nuggets, and works well for weed control also because it is low in nutrients and thus won’t fertilize plant starts below.
CONTACTS: California Department of Pesticide Regulation, www.cdpr.ca.gov; The Garden Doctor, www.the-garden-doctor.com.
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