Using chemicals on your lawn may put your health (and the health of those you love) at risk and can harm animals and ecosystems, too. Here’s how: Applied chemicals may be inhaled or absorbed through the skin (or in the case of children, pets, and wildlife, through the mouth!). And people and pets can track the chemical residue indoors and onto floors, rugs, and furniture. Bees, butterflies, other insects, spiders, birds and other wildlife that enter your yard can also be affected, and chemicals can be washed into local ecosystems, affecting fish and other creatures in local lakes, rivers and streams. The good news? You do not need these chemicals to have a healthy lawn.
What types of chemicals are used on lawns?
- Fertilizers add nutrients to soil to help grass (and other plants) grow faster. These chemical products tend to be the least toxic to people, pets, and wildlife but can still cause harm.
- Herbicides are formulated to kill plants, which makes them more risky than fertilizers. Some affect only broad-leaved plants and some (such as glyphosate) can kill grass, too.
- Insecticides, as the name implies, kill insects. These chemicals tend to pose the greatest risk to people, pets, and wildlife because insects are also in the animal kingdom.
Fertilizers
Lawn fertilizer ingredients like nitrogen and phosphorus can wash away from our lawns and into our lakes, rivers, and streams. These water bodies can then become eutrophic—suffer from nutrient overload. About half of North American lakes are eutrophic. In these lakes, dense mats of algae/plants may grow, blocking sunlight from reaching the water’s deeper layers and reducing growth of fish and other aquatic creatures. As these mats die off, the oxygen level of the water drops, which can lead to die offs of fish and other aquatic creatures. Dense weeds can also make swimming and boating difficult and unpleasant. Read about eutrophication in Lake Erie.
Also worrisome: Nitrates/nitrites in fertilizer may end up in city water systems or wells, where they pose a serious risk to babies and animals as they reduce the blood’s ability to carry oxygen. Children, pets, and wildlife can also get sick if they walk or roll around on or ingest grass recently treated with fertilizer.
And finally, over-using fertilizer (especially chemical ones) can change soil in ways that result in poorer growth of plants like grass. Check out Chemical Fertilizer: A Guide to the Good, the Bad, the Ugh-ly.
Herbicides
There are many chemical herbicides, and how they affect people, pets, and ecosystems varies. A brief look at two common ones:
- 2,4-D kills broad-leaved weeds without killing grass so is often used on lawns. The WHO lists it as a possible carcinogen, with some studies showing that farmers and other people who use it at work have a higher risk of lymphatic cancers. Dozens of studies have shown a link between 2,4-D and thyroid disorders. One study in dogs showed that 2,4-D increased their risk of lymphoma. Dogs can also be poisoned if they eat grass treated with this chemical. Read an article on dogs, lawn care, and cancer. In addition, 2,4-D can be very toxic to fish and other aquatic life.
- Glyphosate is the key active ingredient in Roundup, one of the most widely used weed killers in the world. It’s generally not used on lawns because it kills grass, too, but may be used against weeds in driveway cracks, patios, gutters, etc. The World Health Organization (WHO) has classified it as probably carcinogenic in humans. It can cause harm to the natural world as well: The U.S. Environmental Protection Agency says Roundup likely harms 93% of threatened and endangered species, and glyphosate has been shown to damage bees.
Another worrisome issue with herbicides is they contain other chemicals considered inert (inactive) so not listed on the label but may be even more harmful than the active ingredient. Read an article about Roundup containing an ingredient that suffocates human cells.
FYI: Cosmetic use of glyphosate and 2,4-D is illegal in Ontario, with some exceptions. Even so, you can drive around town and see many emerald-green lawns without a single weed. It’s possible some of these homeowners are diligent weeders, but illegal use of herbicides is still happening. And these chemicals can still affect you even if you don’t use them. If a neighbour’s lawn is treated, the spray can drift over to your yard. Because cosmetic use of herbicides is restricted, those with herbicide-treated lawns may not warn you before your children or pets walk or play on their lawn.
Insecticides
Cosmetic use of chemical insecticides is also restricted in Ontario. As with other chemicals used in yards, insecticides can be tracked inside by children and pets and washed into lakes, rivers, and streams. Pesticides kill insects by damaging their nervous system, interfering with growth, disrupting their ability to absorb nutrients, or targeting their ability to breathe. These are not chemicals you want anyone you love exposed to. Children and fetuses are at greatest risk. Read about keeping children and pets safe from pesticides.
Another issue is these chemicals generally kill all insects—including bees and butterflies—as well as spiders. The aphids or earwigs or whatever insect you are mad at it will be gone, but a lot of good bugs will be lost, too. Read a fact sheet on lawn and garden pesticides.
Is there any good news?
Yes! First, it’s ok to have an imperfect lawn. When you think about it, the modern lawn is bizarre. People spend a huge amount of effort to get grass to grow only to cut it, collect the clippings, put them out for the city to collect/transport to the landfill, then spray fertilizer and other chemicals so their lawn will grow faster so they can cut it more often. Phew! But you can free yourself from the treadmill of traditional lawn care:
- Test your soil to determine the pH and nutrient profile. This information will guide your fertilizer choices.
- Apply natural treatments such as compost or composted sheep or cow manure rather than chemical fertilizer.
- Set your mower blades higher as taller grass shades the soil, retains moisture, and discourages weed growth. Try to mow often enough to avoid removing more than one third of the grass height.
- Water deeply but less often to encourage strong root growth. Overwatering can be just as bad as underwatering—leads to shallow roots and more weeds. And water in early morning—evaporation is reduced and the grass dries before evening, minimizing disease risks.
- Aerate (punch small holes in the soil surface) in spring or fall every one to two years to reduce soil compaction, improve water/soil circulation, and help nutrients reach grass roots.
- Overseed your lawn to fill in bare spots and reduce gaps that weeds love to fill. Choose grass species suited to our climate and your soil/shade conditions.
- Remove weeds without chemicals:
- Use herbicide alternatives like iron-based ones (follow manufacturer directions as these work differently from typical chemical herbicides)
- Hand pull weeds or use a weeding tool
- In gardens, use a rotating stirrup hoe to clip off the heads of young weeds—often they will not re-sprout
- Leave grass clippings after mowing to act as a natural mulch, return nutrients and organic matter to the soil, and reduce the need for fertilizers.
- If you feel you have a pest problem, try reframing the issue rather than trying to conquer it: Grubs provide food for birds. Ants in lawns are generally benign. You can also explore whether something you’re doing is contributing. For example, overwatering can favour chinch bugs.
If grass grows poorly in one part of your yard, maybe it’s not a good fit for grass. Consider planting a native shrub or a groundcover such as wild ginger, wild strawberry, foamflower, bunchberry, or bearberry (please do not plant invasive groundcovers like periwinkle, goutweed, and yellow archangel). You can also lay patio stones and make a new area for your family to chill in.
The focus here is lawns, but other plants (such as vegetables and perennials) can benefit from insecticide alternatives:
- Choose disease-resistant veggie varieties and native perennials that are adapted to growing conditions in your yard (soil, shade, etc.) and your local climate
- Maintain healthy, nutrient-rich soil so plants are strong and better able to fend off insects and disease
- Rotate veggie crops around the bed each year to disrupt insect life cycles
- Hand-pick insects off plants
- Use insecticidal soap (buy rather than make your own to be safe)
- Water deeply/less often rather than lightly/often
- Make sure you’ve correctly determined what the species of concern is and whether it’s actually harmful (for example, ants on peonies are fine); use the least-toxic approach to control it
To knock back weeds in patio cracks or driveways, try cleaning/horticultural vinegar or boiling water.
Next up…how about scrapping the motorized lawn mower?
Questions?
Email us at info@cleannorth.org.
