Unwanted Visitors

Natural suppression is the key to enjoying a weed-free garden.

Eric Schneider

June 2009


One of the most relaxing and rewarding endeavors, gardening nurtures the earth as well as the mind, body and spirit. Nothing, however, impedes this serene pastime like the appearance of weeds.
Weeding is an inevitable aspect of gardening. But pesky plants can become overly vigorous, creating a chaotic appearance while hindering the growth of other plants by drawing nutrients and water out of the soil. Although weeds are most obviously a problem when they invade sizable sections of garden, the real difficulty is present long before that, with the soil hosting a bank of dormant weed seeds. Fortunately, there are a number of non-chemical methods you can use to suppress these weeds, in some cases deterring them before they even appear.

Shading Out Weeds

It turns out that not only is soy a potential boon to your personal health but to the health of your garden, too. A 2008 Weed Technology study found that soybeans, which create a densely weed-suppressive canopy, discourage unwanted vegetation in the field. What’s more, they help ward off weeds in subsequent seasons when rotated with a less-competitive crop such as tomatoes by reducing the weed seed bank.

Elizabeth Lamb, PhD, ornamentals coordinator of the New York State Integrated Pest Management program in Geneva, New York, notes that this concept can be applied to the home garden. Instead of rotating between large areas from year to year as on a farm, row-to-row rotation can work in the garden. When considering crops to plant, Lamb recommends selecting ones that can quickly cover the soil.

“Green beans (snap beans) grow much like soybeans,” Lamb says. “Squash and cucumber are pretty good at shading the soil and reducing weeds underneath them.” She also notes that putting in transplants, or seedlings, may give you faster coverage than direct seeding.

Lee Reich, PhD, a gardening writer, lecturer and consultant based in New Paltz, New York, points out that the ideal way to keep weeds from appearing is to let sleeping seeds lie. Rather than trying to reduce the amount of seeds in the soil, his approach is to keep them dormant. “Light and, possibly, increased aeration, are what wake these seeds up. I keep them asleep by never turning over (tilling) the soil,” says Reich. By not tilling, he helps to preserve the natural “horizonation,” or layering, of the soil, which is more in line with the ground in untouched areas.

As Reich explains in his book Weedless Gardening (Workman), “You can’t just stop tilling and garden as usual. I avoid the soil compaction that tilling is meant to cure by laying out the garden in permanently designated areas for traffic and permanently designated areas for plants. This might be beds (raised or not raised) and paths or stepping stones.”

Christine Sevilla, a environmental advocate based in Rochester, New York, agrees. “Weeds thrive in disturbed soil,” she says. “If you must clear an area of plants, replant the area quickly.” Replanting a previously weedy area with any number of perennial groundcovers will not only discourage new weeds, it may allow an underused section of the garden to shine. Weed-suppressive Groundcovers, a brochure that Sevilla designed with Cornell University and the NYS Integrated Pest Management program, provides details about a number of attractive groundcovers, including catmint, lady’s mantle and leadwort, which she notes are “vigorous growers that tolerate a range of conditions.”

Reich also cites pachysandra, vinca and epimed­ium as frequently used and effective groundcovers. In his book Landscaping with Fruit (Storey), Reich says that lingonberry and lowbush blueberry “make beautiful and fruitful groundcovers.”

Mulch’s Many Benefits

Another way to suppress weeds is with organic mulch. “Mulches will reduce the number of weeds that come up, and, over time, reduce the weed seed bank in the soil,” Lamb says. “Just make sure the mulch is something that you want to add back to the soil—and doesn’t have weed seeds in it.”

Though wood chips are the most common variety of natural mulch, there are many other options. “I use compost as one of my weed-free, organic mulches,” says Reich. He also notes that compost has other benefits beyond suppressing weeds, including feeding the soil and decreasing root diseases. And though many people make it a point to clear their yards and gardens of fallen leaves, Reich recommends using them as mulch. “The advantages are that they are usually free, available and weed-free,” he explains. “I suggest a change in aesthetics to anyone bothered by the sight of leaves on the ground. That’s where Mother Nature puts them.”

Knowing your enemy also helps in the battle against weeds, particularly with highly invasive plants. While almost everyone can spot a dandelion, even gardening pros may not identify other invasives until they become a menace. Sevilla leads “weed walks” in the Rochester area to create awareness about invasive plants, encouraging fellow walkers to look for aggressively opportunistic plants (including black swallowwort, oriental bittersweet and Japanese knotweed).

Finally, a tried-and-true method of weed control is simply pulling them. “I do weed,” Reich admits. “It’s easiest to keep weeds in check by regularly patrolling the garden and removing any weeds found before they have established extensive roots and/or set seed.” He advises pulling up the larger roots right where the weed stem attaches. But he adds, “Let the smaller roots stay in the soil to rot, enriching the soil with humus and leaving behind channels for air and water. New plants won’t grow from those fine, small roots.”

While weeding can be an exhausting chore, it leads to the gratifying feeling of vanquishing your foe, if only for a little while. However, by incorporating some of the more nuanced approaches to weed suppression, you may be able to decrease the weeds in your garden, resulting in less time kneeling and more time admiring your perpetual work-in-progress from above.

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