Lawn care without the chemicals

The average yard contains 10 times more chemicals per acre than a typical commercial farm. You can make your lawn less toxic by skipping the nitrogen-rich, fast-releasing fertilizer. Instead, mulch grass clippings when you mow and apply compost once or twice per year.

But what about all of the weeds that can ravage a yard, especially during the summer months? Thick, healthy turfgrass is the best defense because it won’t allow weeds to take root in the first place. Overseeding thin spots in the lawn will help maintain a thick carpet. In garden beds, a layer of mulch, whether bark chips or mulched leaves, will keep weeds down and retain moisture in the soil.

Even with those precautions, some weeds are bound to infiltrate your property. Blasting them with Roundup isn’t the best idea because the health effects of glyphosate, an active ingredient, and other herbicides like it aren’t fully understood. (The International Agency for Research on Cancer, a division of the World Health Organization, recently determined that glyphosate is a probable carcinogen.)

Here are 10 common weeds and pests that plague homeowners nationwide, along with chemical-free measures that should be effective in bringing them under control. For more information, go to the websites of Beyond Pesticides and the Great Healthy Yard Project.

Dandelion

What is it? A perennial weed whose common yellow flowers turn to windblown seed.
Telltale signs. Though a handful of dandelions is no big deal, a lawn that’s ablaze in yellow has underlying problems that need to be addressed.
How to treat. Like many broadleaf weeds, dandelions prefer compacted soil, so going over the lawn with a core aerator (available for rent at home centers) might eradicate them. It also helps to correct soil imbalances, especially low calcium.

Barberry

What is it? An invasive shrub with green leaves and yellow flowers, often found in yards near wooded areas.
Telltale signs. Left unchecked, the shrub’s dense thickets will start to choke off native trees and plants.
How to treat. Cut back the stems and paint their tips with horticultural vinegar or clove oil (repeated ­applications may be needed). ­Burning the tips with a weed torch might also work.

Crabgrass

What is it? An annual weed with a spreading growth habit. It’s common in the Northeast, in lawns with poor soil conditions.
Telltale signs. Lots of bald spots, especially after the first freeze, when crabgrass dies off.
How to treat. Have your soil tested. Lime or sulfur may be needed to adjust the pH. Aeration is also recommended. Corn-gluten meal, applied in early spring, can be an effective natural pre-emergent herbicide.

Kudzu

What is it? An aggressive climbing vine that’s common in parts of the Southeast and the Midwest.
Telltale signs. The thick vine forms a canopy over trees and shrubs, killing them by blocking out sunlight.
How to treat. Pull out the vine and, if possible, its taproot. Be sure to bag and destroy the plant or its vines will regerminate. If the root is too thick, paint the stump with horticultural vinegar or clove oil repeatedly, or burn it with a weed torch.

Canadian Thistle

What is it? An aggressive creeping perennial weed that’s found throughout the U.S.
Telltale signs. Look for outbreaks in vegetable gardens, particularly those with peas and beans.
How to treat. Repeated hand weeding and tilling of the soil will weaken its extensive root system. Planting competitive crops, such as alfalfa and forage grasses, will keep it from returning.

Fig Buttercup

What is it? A perennial weed with yellow flowers and shiny, dark green leaves. It’s common in many parts of the East, Midwest, and Pacific Northwest.
Telltale signs. The weed will start to crowd out other spring-flowering plants. It can also spread rapidly over a lawn, forming a solid blanket in place of your turfgrass.
How to treat. Remove small infestations by hand, taking up the entire plant and tubers. For larger outbreaks, apply lemongrass oil or horticultural vinegar once per week when the weeds first emerge. It might take up to six weeks to eradicate.

Phragmites

What is it? An invasive grass species found nationwide, especially in coastal wetlands.
Telltale signs. Dense weeds can crowd out other plant species without providing value to wildlife.
How to treat. Cut back the stalks and cover the area with clear plastic tarps, a process known as solarizing. Then replant the area with native grasses.

Grubs

What are they? A variety of white C-shaped beetles that live in soil and feed on plant roots.
Telltale signs. Large, irregular sections of brown turf that easily pull away from the soil.
How to treat. Release beneficial nematodes into the soil each year; these tiny roundworms feed on grubs. Milky spore powder works longer-term on Japanese grub beetles. If you’re up for raising chickens, they eat grubs.

Chinch bugs

What are they? Insects 1/6-inch long with a gray-black body, white wings, and reddish legs.
Telltale signs. Copper-colored patches, usually seen during the summer months.
How to treat. Give the lawn a little extra water. Prevent thatch by not overfertilizing or cutting grass too short. Remove thatch with a dethatching rake. For small infestations, drench area with soapy water and cover with a white sheet; the bugs will cling to it, making disposal easy.

Bagworms

What are they? The larval stage of moths, these worms, a half-inch to 3 inches long, hang from the branches of evergreens and ornamental plants.
Telltale signs. Early signs include brown or stressed needles and leaves. Heavy infestations can defoliate a tree or shrub.
How to treat. Plant asters or black-eyed Susans nearby. They attract bagworm-killing insects, such as parasitoid wasps and tachinid flies. For major outbreaks, apply Bacillus thuringiensis, a naturally occurring bacterium sold at most garden stores.

Sometimes you have to use your hands

When faced with just a few weeds, it’s best to remove them by hand. Mechanical tools keep you off your knees, though in the past we found they couldn’t always pluck weeds with long taproots, especially from highly compacted soil.

Diane Lewis, whose Great Healthy Yard Project shows homeowners how to maintain attractive yards without chemicals, likes Fiskars’ uproot weed remover, $30. With its step-down and pullback action, the tool’s stainless-steel tines are designed to pull up the weed and root system. “After a good rainfall is the ideal time,” Lewis says, “since the loosened soil will give up the whole weed.”

Editor's Note: This article also appeared in the June 2015 issue of Consumer Reports magazine.

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