The postcard immaculate lawn, snipped and blown to perfection with nary a dandelion or dead leaf in sight, is a source of pride for homeowners around the world. But if you’re not using an old-school, manual, reel mower, lawn maintenance can come with a high environmental price tag.

Last year, California became the first state to enact a ban on the sale of new gas-powered lawn equipment like mowers, leaf blowers, and chainsaws, effective 2024.

These machines belong to a category of spark-ignited engines called small off-road engines, or SOREs. Gas-powered SOREs have come under scrutiny because they’re less efficient than on-road engines, like cars, and go largely unregulated, emitting a cocktail of dangerous pollutants including nitrogen oxides (NOx) and volatile organic compounds (VOCs). Together these pollutants react in sunlight to form ground-level ozone, the main ingredient in smog and a harmful greenhouse gas that contributes to climate change.

While SOREs aren’t the only greenhouse gas emitters, the damage they inflict is hard to overlook. The Washington Post reported that in 2018, gas-powered lawn and garden equipment guzzled almost 3 billion gallons of gasoline in the United States, roughly the same amount as 6 million passenger cars running for a year. In 2020, SOREs emitted more NOx per day in the state of California than light-duty passenger cars.

“The car that you’re driving on the road, that’s actually a really sophisticated engineered product that has all kinds of controls on it,” says Albert Presto, a mechanical engineering professor at Carnegie Mellon University. “There are just way fewer controls on a lawn mower.”

On-road vehicles, for example, are equipped with a catalytic converter — a device that controls exhaust emissions by transforming toxic compounds like NOx or carbon monoxide into relatively safer gases like carbon dioxide and water vapor. Gas-powered lawn mowers, generally, aren’t equipped with such devices.

With the urgency to curb climate change only building, some say it’s time to look more closely at the environmental cost of our love affair with lawns and consider passing on the grass.

That’s a message Emma Baker can get behind. She grew up looking out onto a clean-cut lawn on the shores of Lake Michigan.

“My dad wasn’t a big lawn guy, but he did all the right stuff,” Baker remembers. “Mowing once a week, spraying broadleaf herbicide in the spring… it always looked, you know, sort of green and perfect.”

Today, the Lansing, Michigan horticulturist’s backyard is the antithesis of the grassy expanse she recalls from her childhood. It’s home to pollinators, rabbits, and a family of opossums because Baker doesn’t bother cutting the grass. Instead, she’s left the design of her backyard to the squirrels, who’ve planted oak and maple seedlings, among other florae. It’s all part of an effort to rewild her green space. In other words, she’s letting nature take care of itself.

“I started realizing that by making these lawns, you know, there’s inherently a trade-off,” she said, adding that every square foot of grass is a piece of forest or grassland that could have been. “Nobody really needs to be putting so much sweat equity into destroying an ecosystem.”

Rewilding is a restorative ecosystem practice and movement that’s gained traction in recent years, particularly when it comes to lawns.

Homeowners across the United Kingdom, for example, participate annually in No Mow May, an initiative that encourages folks to park their mowers for the month to restore biodiversity in their yards. Today, the call-to-action has grown roots in the US as a rejection of the traditional American lawn, a landscape whose origins can be traced back some 300 years to Europe.

Historically, lawns were symbols of wealth and status. Only aristocrats could afford to maintain them, because they required large amounts of space and physical labor. “It’s kind of a British and French invention, which then carried over into other parts of the world,” says Urban Plant Ecologist Tracy Fuentes.

Lawns took root in the US after they were brought over by immigrants from Northern Europe. Even past presidents Thomas Jefferson and George Washington, Fuentes adds, had their own homes modelled after estates in England and France with large swaths of lawn. To this day, lawns can be found in nearly every American neighborhood and remain symbols of wealth and status. But ecologically, they are hard to justify.

“You might say that it’s rather selfish of us humans to take up all of the space for buildings and streets, and then when we do have green space, we put in a lawn that only has space for a couple of species,” says Fuentes.

Lawns are essentially monocultures, environments where only one grass species is cultivated. Monocultures drain the soil of its nutrients. That means that to maintain one, you need to add fertilizer, whose runoff can pollute water systems. They also require a lot of water to maintain that emerald green look. In the US, for instance, nearly 3 trillion gallons of water is spent on maintaining manicured greens that provide little habitat to wildlife.

They’re also easy targets. Monocultures are synonymous with putting all your eggs in one basket — because they lack the diversity that builds up resilience to stressors like disease or disaster, they can be taken out in one fell swoop. This is particularly true of monocultures like single-crop fields.

Rewilding transforms monocultures into polycultures, where multiple species are cultivated together to create a resilient and diverse ecosystem. For some people, rewilding is an intentional practice of planting wildflowers or shrubs to create habitat for pollinators and wildlife. For others, it’s a total abandonment of traditional lawn care.

In Baker’s front yard, witch hazel, coral bells, and asters are planted amongst a scattering of mulch that camouflages the return of indigenous flora, like violets, to her urban half-acre. She has had to be more intentional about rewilding her front yard because she has to follow the municipal code. While she’s never gotten a negative comment from her neighbors, “from the city, it has been a little bit of a struggle,” she says.

In American cities, green space is tightly controlled. Many communities have grass ordinances or vegetation maintenance standards that discourage rewilding because of worries that overgrown vegetation could attract rodents, snakes, ticks, and dangerous wildlife. In Lansing, Baker can’t let her grass grow taller than eight inches.

That’s because “people are more comfortable with rewilding if it looks like somebody’s taking care of [the space] and not if it looks like somebody just let it go,” says Fuentes.

Baker has been ticketed before. She says she’s had to pull weeds to keep the city from brush hogging her yard — the most serious penalty for not abiding by municipal vegetation standards.

“I think they want to see that I’m doing something,” she says. “Which is funny to me, because that’s the whole idea of lawns, right? You’re okay if you’re doing work [maintaining your yard], but if you’re not working then you’re lazy and bad and wrong.”

However, the return of wildlife to her urban green space makes it all worth it, she says.

Mere months ago, Glasgow’s COP26 climate conference set the stage for a new round of bold climate commitments. While the environmental footprint of a lawn mower might not be a top priority for the world’s governments, unlearning lawns and rewilding yards is becoming a greater one for homeowners who want to do their part.