Lawn Care for a Healthier Watershed

This is a section of a five-part series produced by FLOW to educate residents about backyard conservation.

Example backyard with native plants and gardens rather than lawn.

Photo by Smadar Sonya Strauss

Lawn is pervasive in the American landscape. There are an estimated 40 million acres of lawns across the country, making “lawn” the largest irrigated crop in America. Our lawns use 7 billion gallons of water daily and we dole out 80 million pounds of pesticides and 90 million pounds of chemical fertilizers annually just for our grass. This dilemma extends to the Lower Olentangy Watershed, 40% of which is dedicated to lawn by land area. 

So why do we do it? Why do we spend so much time, energy, money, and space on our lawns when they provide so little ecological value? One acre of tree canopy absorbs seven times the water of lawn rather than allowing that water to runoff. Grass isn’t indigenous to the Americas, while shrubbery and wildflowers – that support native food webs and provide beauty – are. Converting more lawn into gardens, planting native trees and shrubbery, or even transforming your backyard into a prairie or wetland is easier than you might think and better for the watershed than you might know. 

However, most of us might not be willing to abandon our entire lawns for alternatives. Even still, there are ways to mitigate the effects of our lawns to better the health of our environment. Simple adjustments to how you mow, water, fertilize, and apply pesticides can make a big difference for our watershed. 

Rotary push mower with orange wheels cutting the grass and leaving clipping on lawn

Creator: BradWolf; Getty Images/iStockphoto

Mowing is a chore that emits greenhouse gasses – simply put, there is some room for improvement. Mowing higher (cutting your grass taller) produces healthier grass that requires less frequent mowing. The longer blades are able to absorb more sunlight to grow deeper roots and shade the ground, allowing it to hold more moisture. Longer grass directs its energy to health rather than growth, so it requires less frequent cutting. Thicker, longer grass also makes it more difficult for weeds to grow. You should cut your grass to be 2.5” to 3.5” or at your mower’s highest setting. A good rule of thumb is to never cut off more than one-third of the grasses’ height. You can also save time by leaving short grass clippings on your lawn or “grasscycling.” This way, clippings act as an organic fertilizer rather than taking up space in a landfill or ending up in our waterways where the excess nitrogen can cause algal blooms. 

Americans use more water for lawns than for farms. The everyday sprinkler system wastes water and isn’t best for grass. Watering deeply but not as often makes for better roots and more drought-resistant grass. You should apply about 1” of water to wet the top 6” to 8” of soil in the early morning to reduce evaporation. Watering at night can increase the chances of disease. To determine when to water, look for signs of wilting such as a dulled color or footprints that stay compressed for more than a few seconds. During extended dry spells or droughts, a lawn can go dormant and still survive with only about ½” of water every 2 to 3 weeks. 

Over-fertilizing in the midwest is one of the main reasons for the growing dead zone in the Gulf of Mexico. Good lawn management can reduce the need for fertilizing and limited, careful fertilizing can mitigate some harmful effects. Organic fertilizers provide benefits that synthetic fertilizers lack by preserving the biotic quality of the soil. Manures, meals, compost, minerals, and processed sewer sludge are all synthetic fertilizer alternatives. If using organic fertilizer, apply them less frequently and in the fall because they release nutrients at a slower rate. Generally, only apply any fertilizer twice a year, once in the spring and once in the fall. Do not apply fertilizers or pesticides within twenty-four hours of rainfall to prevent them from running into our water supplies. Similarly, keep fertilizers off impervious surfaces such as sidewalks or driveways by sweeping spills and using a side guard on drop or rotary spreaders. Generally, healthy soil has a loamy texture, is a dark color, and has a good balance of nitrogen, phosphorus, and potassium. If the acidity of your soil is off, you can sprinkle lime or sulfur on your lawn. You can determine the needs of your soil by using a simple soil test and only apply the needed nutrients.

Thatch build up on grass sampleMeasures to improve water filtration, nutrient quantity, and health of grass can be hindered by an overly thick layer of thatch. Thatch is a layer of dead plant material that sits on the soil. Overuse of fertilizer or other factors can cause this layer to exceed ½”, making it too thick for healthy grass. Normally, thatch build-up is prevented by microorganisms and earthworms decomposing the dead matter. You can combat thatch buildup by raking your lawn or mechanically removing soil cores through core aeration. You can do core aeration yourself by renting the equipment from a local hardware store. The best time to aerate is spring or fall. Core aeration should be done in combination with sprinkling a thin layer of topsoil or “top dressing,” which is a surface application of compost. Make use of fallen leaves by chopping them up with your mower then spreading the product with a rake to your soil after aeration. 

Finally, using integrated pest management (IPM) techniques by combining chemical, biological, and mechanical pest control can lighten the impact of pesticides. With good soil quality, healthy thatch levels, and native plants adapted to the environment (or even some that attract pest predators), you should find your lawn to be more pest resistant. Rather than using reactive measures like sprays and chemicals, try preventing weeds by taking holistic good care of your yard. Weeds and pests cannot be completely eliminated, but luckily a lawn can look weed-free even with some straggling weeds. If you are to use a pesticide, first consider using more targeted pesticides with little or no residual effect such as insecticidal soaps, horticultural oils, or corn gluten. When using a synthetic pesticide, use them sparingly and spot treat, read the entire instruction label, wear protective gear, and store and dispose of the pesticide properly. 

For more information about lawn management and backyard conservation, you can consult FLOW’s website, information from the EPA, or hire a local professional lawn care service. You can make a meaningful difference in your community and environment simply by being deliberate and careful in how you do your yard work.

Plant some late blooming “secret flowers”

Join SER (Society for Ecological Restoration) to search for secret flowers! Late-blooming flowering plants like asters, goldenrods, bonesets, and white snakeroot are hiding in your yard and other places around the city. They look like “weeds” all summer, but in the fall, they reveal that they’re secretly flowers that benefit people, pollinators, and wildlife. Follow along in your own yard or a local park, as we show off secret flowers at our campus habitat restoration site and collect their seeds to plant in the spring.

As you plan your garden this spring, consider planting some of these habitat superstars!

Neonics: What They Are and Why You Should Avoid Them

Neonicotiniods, also referred to as neonics, were developed in the 1980s and soon became the most used insecticide in the world. Their popularity spread in part because manufacturers advertised them as “safer” insecticides. By some definitions, this is true. Neonics have a relatively low toxicity to mammals and humans. They can also be applied in a targeted manner, decreasing the amount of run-off product. Yet only a few decades later, neonics have been largely banned in the European Union and have come under scrutiny in the United States. So, what is the problem?

Study after study have linked declining bee and bird populations to the use of neonics. Manufacturers claim that in the real world, wildlife only encounters quantities that are sublethal. The problem is that a sublethal amount of the toxin is enough to cause enormous damage to both an individual and, in the case of pollinators, its colony.

Neonics have several modes of application. These are: seed coating, drenching the soil around the base of a plant, trunk injection, dissolved in irrigation water, or sprayed on leaves. Neonics are a synthetic modification of nicotine, and they work in a similar manner. They are systemic insecticides, which means that regardless of the mode of application, the toxin binds to cells and becomes incorporated and distributed throughout the whole plant. If a bee encounters the pollen of a plant that grew from a treated seed – that bee becomes exposed to the toxin. Is such exposure enough to be dangerous to the bee? Unfortunately, studies show that it is.

Bee on coneflower

A pollinator enjoying an Echinacea flower. Photo by Sonya Afanasyeva.

In the mid-2000s scientists noticed a decline in the number of beehives and started to inspect the effects of neonics on bees. Throughout the 2010s, studies determined with growing certainty that neonics were in fact contributing to the decline of bee populations. According to a 2019 study, neonics have made the American agricultural landscape 48 times more toxic to honeybees than it was 25 years before. The Bombus Affinis, a North American bumblebee, has decreased in 90% of its natural habitats. Much of this decrease has been attributed to neonics. Studies have also discovered that the toxin can be found in soil and pollen up to two years after treated seeds were planted.

Worker bees have complex routines. They learn to understand smells and patterns and memorize the best routes to and from food sources. Neonics affect bees’ nervous systems. They hinder their ability to fly, learn, and memorize. While an encounter with a sublethal dose of neonics will not kill a bee, it affects its health and ability to work. An exposed bee is likely to spread the toxin and bring it back to its hive. As more bees are affected, the threat of colony collapse increases. Neonics can also harm the queens’ ability to reproduce, leading to a decline in worker bee production. Affected larvae take longer to develop and exposed adults have shorter life spans. The toxin can also disrupt bees’ immune systems, making them vulnerable to viral infections.

Songbird with seed

An American songbird. Photo from inhabitat.com

Declines in bird populations have also been linked to neonics. Insect eating birds have been harmed both by a decline in their food source and by consuming affected insects. More notable is the dramatic decline in North American songbirds. Much like nicotine, neonics act as an appetite suppressant to seed eating birds. Birds migrate during spring when farmers are planting crops. During migration, gaining weight at stopover sites is crucial for birds. If a bird consumes part of a treated seed, it stops eating and loses weight. One study tracked birds that consumed a tenth of a treated seed. The birds were lethargic and did not have an appetite. They lost 6% of their body mass within six hours, and many stayed behind to recover for an extra three days. Even if a bird recovers, the delay can still damage its chances of surviving and reproducing.

There is good news, though. The Environmental Protection Agency is very concerned with the continued use of neonics in the United States. The agency is working on legislation that would ban or restrict their use. Early in 2019, over 140 garden retailers, including Home Depot, Lowe’s, Walmart, Kroger, and Whole Foods, committed to cut products that contain neonics. Most stores have not yet announced whether they have accomplished this. Home Depot claims to be 98% free of such products. They also label the plants that contain neonics, making it easier for shoppers to avoid them.

You can also help to decrease the spread of neonics. When shopping for plants, ask your nursery staff if they know which products have been treated with neonics. Avoid insecticides with these ingredients: imidacloprid, acetamiprid, dinotefuran, clothianidin, and thiamethoxam, thiacloprid, nitenpyram. Finally, plant flowers that are safe and attractive to pollinators in your yard. Even small urban gardens are valuable to pollinators, who are in turn vital to the health of our ecosystems.

Article by Sonya Afanasyeva

Featured photo: A pollinator friendly garden. Photo by Sonya Afanasyeva.