Robot mowers could change how we care for our lawns

Aug 01, 2023

Add up the suburban plots, golf courses, playing fields and parks in the United States, and you get some 40 million acres of lawn. The price of maintaining all that turf is high: The U.S. Energy Department reports that mowers consume 1.2 billion gallons of gasoline annually, and lawn equipment is responsible for 12 percent of all carbon monoxide emissions, according to the U.S. Environmental Protection Agency. Each gas lawn mower in use adds more than 85 decibels to noise pollution levels.

Some states have already banned or restricted small gas engines, and municipal-level bans have been enacted around the country. Homeowners’ associations are cracking down on noise pollution, and Congress is considering legislation to develop more noise control programs. The gas mower may be headed for extinction, many experts say.

Evolving technology has helped new mower models gain a foothold: In 2021, according to market research firm Fact.MR, electric and battery-powered mowers accounted for half the revenue of the global lawn mower market. They still require human energy and an investment of time and sweat, though.

Lawns are a time and water suck. Build a meadow instead.

Enter autonomous lawn mowers. They have been around since the mid-1990s, but they were largely a novelty product. That is starting to change with newer, easier-to-use models. Think of them as the outdoor equivalent of a robot vacuum, patrolling a defined area without human labor. Like battery-powered mowers, they reduce air and noise pollution, and some say they also help cultivate a healthier lawn. There are still kinks to be worked out though: Not every property is suited to an autonomous mower, and prices are still high enough to make many homeowners balk.

Rather than cutting the lawn once every week or two, as most people do, auto-mowers roam constantly, with small spinning blades on the undercarriage trimming grass a few millimeters at a time. These frequent mowings keep grass healthier, says James Murphy, director of the Center for Turf Grass Science at Rutgers University.

“If you clip the grass so you’re not taking very much leaf material off at any one time, that’s less stressful for it,” he says. A homeowner using their conventional mower every day or two could see the same benefits, Murphy adds, “but it comes down to how much time and energy you have. That’s where autonomous mowers have the potential to be better.” In Europe, where auto-mowers have been in widespread use for a number of years, studies have found that robot-mown grass is denser, with fewer weeds.

While some conventional mowers deposit clippings in a bag, others leave them behind as mulch. That is beneficial, Murphy says, to a point. Long clippings can form a thick, loose “thatch” that causes structural issues around the roots of the grass. The tiny, quick-decomposing clippings dropped by an auto-mower mulch the grass without building a deep thatch layer.

Many auto-mowers also run at night, when Murphy says the turf is “less stressed, rather than in the heat of the day, in the full sun, while it’s actively growing and moving water to cool itself.” Plus, mowing at night can dislodge moisture, Murphy says, which “could potentially offer an indirect kind of disease control.”

In addition to essentially eliminating a major source of noise pollution and emissions and drastically reducing power consumption, autonomous mowers may have ripple-effect benefits for sustainability.

The lightweight robots can reduce storm water runoff, says Dan Mabe, founder of the American Green Zone Alliance. “Unlike big equipment, they’re not compacting the soil, so it’s able to absorb more water.”

Joe Langton, whose Illinois-based landscaping firm, Langton Group, specializes in auto-mowers, says he’s able to use less herbicide because crews have more time to pull weeds by hand. Langton charges clients a monthly subscription fee to install and maintain the robots, which he says lowers his overall costs.

Shifting his focus to auto-mowers, Langton says, also shrank his company’s footprint in a carbon-intensive industry by reducing the number of gas engines his crews use and eliminating the need for huge trucks and trailers to haul equipment.

Mabe spent years landscaping — and paid a price. “Inhaling exhaust for years on end, you can develop respiratory issues,” he says. “For me, there was a lot of bronchitis and lots of respiratory infections. There was ringing in my ears.” Part of AGZA’s mission is to create healthy environments for landscaping professionals. Putting robots on the crew, Langton says, has improved conditions for his employees.

Most auto-mowers use boundary wire — similar to an invisible fencing system — to outline the mowing zone and guide the bot back to its charging station. The system works in many yards. But on larger properties, burying or securing that much wire can feel daunting, and some people don’t want to monitor the boundary for breaks and do repairs.

New technology could help. Models such as the Ecoflow Blade and Husqvarna 450X EPOS are wireless, using satellite and antenna systems to rove no-mow zones and transit paths between cutting areas. They do, however, require a more complex setup (and, in the case of Husqvarna, professional installation). And in yards with a lot of trees or landscaping, the mowers may frequently lose contact with the satellites and need to be manually moved or restarted. Just as a robotic vacuum sometimes gets stuck in odd corners, a mowing robot may need help.

“One concern you always hear is about losing control,” says Murphy. “Is it going to run into something, or damage something? You don’t want it running into your flower beds and chopping up your landscaping.”

The kinks are being slowly worked out, says Chad Fuhrman, director of product management, robotics North America at Husqvarna Group, through regular updates to software and hardware.

And cost may be a barrier all its own. While most companies sell a boundary wire model for the average yard for under $1,000, the Ecoflow Blade retails for close to $3,000. With installation, the Husqvarna model is more than $6,000.

Even so, sales are climbing, says Furhman, as people decide the benefits are worth the investment. Older people see automated lawn maintenance as one less reason they might have to move out of their home, he says, and younger homeowners, innately comfortable with technology, are happy to outsource tedious tasks.

“You do have to be comfortable with something operating on its own, while you’re not there to watch it,” says Murphy. “But if you think about it, we do this all the time with things like dishwashers. There are still a few technological things that aren’t quite perfected, but when they are, I think the autonomous mower may become standard.”

Langton finds that once people do adopt an auto-mower, they quickly get attached; they enjoy watching the robot work, and some even anthropomorphize.

“The names are awesome,” he says. “People call them Snips, Casper … one of my customers named his robot Albert the 8th. They become connected to them like it’s a pet.”

Kate Morgan is a freelance writer in Richland, Pa.