A Chemical-Free Yard: Rid Your Lawn of Pesticides, Chemical Fertilizers, Weed Killers and Insecticides

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Native plants resist bugs and disease with little maintenance and zero danger to pets or humans.
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Pets can track landscape chemicals into your home, which is particularly dangerous for children.

You want to give your pet a lush outdoor space to run and roam, but many fertilizers, herbicides and pesticides use harmful chemicals. Almost all chemical yard treatments have a natural alternative. If you or your neighbors must use them, understanding the chemical composition of fertilizers, weed killers (or herbicides) and pesticides could save or prolong your pet’s life.


Animal health experts agree that fertilizers–whether synthetic, natural (animal manure or worm castings) or a combination–are relatively safe around pets. Most formulations are composed of three primary elements normally present in our (and our pets’) bodies: nitrogen, phosphorous and potassium.

If your pets eat fertilized grass, “it doesn’t cause any major problems–just some mild gastrointestinal irritation,” says Justine A. Lee, a certified emergency critical care veterinary specialist and author of It’s a Dog’s Life…but It’s Your Carpet and It’sa Cat’s World… You Just Live In It. Seek emergency medical care if your dog eats fertilizer straight out of the bag. In higher doses, it could be toxic.

Weed killers

Weed killers, or herbicides, are not terribly problematic from a toxicology perspective, says Steven R. Hansen, a veterinarian and senior vice president at ASPCA Animal Health Services. “Most have a limited effect on animals.”

Many weed killers contain the herbicide glyphosate. “If an animal ingests it, it can cause some vomiting, but nothing life-threatening,” Lee says–as long as the animal doesn’t ingest the concentrated (nondiluted) form. Still, the EPA has concerns about glyphosate levels in drinking water and lists kidney damage and reproductive effects as its long-term health effects, so avoid herbicides that contain this chemical.


Insecticides also pose a threat to mammals. Insecticides containing organophosphates or carbamates (specifically the N-methyl subclass) can damage an animal’s nervous system, leading to muscle weakness or paralysis. Most organophosphates have been phased out of use, but some outdoor products do contain carbamates–the presence of these is generally not indicated on product labels. The EPA says these formulations should not pose a risk to pets or humans, as long as you follow label guidelines for application. You can avoid them entirely by choosing an organic, natural product instead.

Systemic rose insecticides (products absorbed through the root system to specifically kill insects that damage roses) often contain organophosphates or carbamate. This poses a specific danger because gardeners frequently mix bonemeal, fishmeal or blood meal into these products, making them more palatable and attractive to dogs. Plus, “the bone meal can form a rock-hard foreign body in their stomach or the blood meal can result in a severe inflammation in their pancreas, causing vomiting and diarrhea,” Lee says.


Rodenticides, designed to eliminate mice, rats, gophers and other rodents, are dangerous. Extremely potent slug and snail bait products are dangerous to wildlife as well as dogs, cats and children, Hansen says. “The challenge with slug and snail bait is that they are very attractive to animals.”

A dog can survive ingesting small amounts of mouse and rat poison pretty easily because of their body weight, Hansen says, but all rodenticides should be handled very carefully (if at all). “They are designed to kill things.”

You Don’t Need Chemicals

Pam Geisel, coordinator of the University of California’s Statewide Master Gardener Program, and Mindy Pennybacker, former editor of The Green Guide, offer these tips for a safe, less chemically dependent lawn.

? Reduce ornamental turf areas and plant with native species or those that match the microclimate, which will cost less to maintain and provide a habitat for native birds, bees and butterflies. Native species have adapted to survive the pests in  their habitat.

? Follow an Integrated Pest Management program, which manages pest damage by the most economical means and with the least possible hazard to people, property and the environment. (For more information, see www.epa.gov/pesticides/factsheets/ipm.htm.)

? Top dress your turf with well-decomposed compost or leave grass clippings on the lawn. See “Grasscycling–what to do with the grass clippings” at www.ipm.ucdavis.edu/tools/turf/maintain/grasscyc.html.

? Choose eco-friendly herbicides. Many products use natural solutions such as vinegar, corn gluten, fatty acids and plant oils.

? Make your own (less toxic) insecticides. Liquid soap kills aphids, sawflies, spider mites, scale and whiteflies. Mix 2 tablespoons of plant-based liquid soap with 1 gallon of water and spray. For extra strength, add a few drops of plant oils such as rosemary, peppermint or clove.

? Try ground red pepper and powdered garlic or onion. Soak two to five handfuls in a gallon of water, then filter out solid matter. Water your vegetables with the liquid two to three times a week.

? Dehydrate crawling insects. Use diatomaceous earth, a nontoxic powder made from the crushed fossils of single-cell, algae-like organisms. As insects crawl through diatomaceous earth, it lacerates their outer shells; they then dehydrate and die. Apply the powder around your lawn’s edges or at the base of plants (www.extremelygreen.com).

? Mow at the right height for the grass type, generally when the grass is one-third higher than desired–for example, for a 3-inch height, cut when grass is 4 inches. See “How much, when, and how often to mow” at www.ipm.ucdavis.edu/tools/turf/maintain/mowamt.html. Cutting too short (“scalping”) allows more light to reach the soil, damaging turf health while increasing weeds. Water deeply but infrequently to discourage crabgrass, which thrives with shallow watering.

? Weed by hand. It’s effective for reducing perennial weeds such as Dallis grass and spurge before they go to seed.

A freelance writer and author of The Gifts of Change, Nancy Christie writes frequently about healthy living.

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