I’ve never enjoyed cutting the grass. For years, I struggled with an old inherited gas mower that refused to die but often refused to start. Then I had a cheap electric mower with a cord that I had to keep shifting around. When I got the chance to try a robot mower, I jumped at it, picturing chilling on the deck with a cool drink, watching a robot mow my lawn. Sadly, the reality was somewhat different.
Early robot mowers were incredibly bad. I’m talking churned grass, rescue messages blowing up my phone as one robot mower after another got stuck in a flowerbed, and large strips of long, untouched grass all around the edges. Sometimes they’d try to cut the grass in the rain and just get covered in the stuff. Sometimes they’d spend hours trying to line up with the charging dock and somehow keep missing.
But the best robot lawn mowers are actually good now. If you’re willing to drop some cash, you can eliminate mowing the lawn from your to-do list and maintain a lawn pristine enough to satisfy the most demanding homeowners association. Cheaper variants, well, not so much; they mostly still suck. But if you’ve been on the fence about a robot mower, it might be time to climb down.
The Garden Path
The first few robot mowers I tested had real trouble with pathfinding, often got randomly stuck along borders, and didn’t always make it home before running out of battery. Robot mower navigation is getting better. Since I started testing robot mowers three years ago, their ability to reach the designated cutting area, mow it, and return to the charging base station has improved enormously.
Here’s the evolution of robot mower navigation technology.
Boundary Wire: Early models, and some of the cheaper options on the market today, require you to lay boundary wires, which means digging and marking out an area around your lawn. It’s a pain, it’s messy, and it doesn’t handle odd shapes or multiple mowing areas well. I don’t recommend any boundary wire mowers, though if you have a simple square lawn with a border all around it, this type could be a good way to save money.
Satellite: The next advancement was real-time kinematic GPS, which meant planting an antenna with a clear view of the sky adjacent to your lawn. It connects to satellites to track positioning accurately and, working alongside the base station, can instruct the mower to cut down to the inch. My current top pick from Husqvarna uses this system, and it works well, provided you don’t have tall trees or buildings around your property. But there are occasions when GPS mowers will just sit there searching for satellites.
Light Detection and Ranging (Lidar): This system, also used by self-driving cars, fires out rapid laser pulses to map the terrain in 3D. It enables mowers to cut grass under thick tree canopies or near tall buildings where GPS signals usually fail.
AI Vision: Some mowers now employ cameras to recognize lawn areas, borders, and obstacles. Robot mowers with AI vision can potentially avoid stray footballs, cats, other critters, and maybe even pet mess. But they can also be too sensitive, stopping for fallen branches, leaves, or overhanging plants.
Some of the top mowers, like the Mammotion I’m currently testing, employ a combination of the last three technologies to map and cut areas accurately, navigate reliably to and from the charging base, and avoid unexpected obstacles. None of them is foolproof. My top pick chewed up a deflated paddling pool, but if you set the sensitivity too high, they leave areas uncut.
In addition to finding their way, many of the latest robot mowers are built to handle rough terrain. Not too rough, but fine for a bumpy garden or a yard with steep inclines. Some models even come with interchangeable tires, so you can throw on grippier wheels when you need them. But it’s important to check what terrain and inclines your mower can handle upfront. Four-wheel-drive or all-wheel-drive mowers are best at handling steep or uneven ground.
The Cutting Edge
Traditionally, robot mowers have been terrible at cutting all the way to the edge of your lawn. Most of the early robot mowers I tested left a thick border of uncut grass, up to 1-foot wide. I don’t think this issue is entirely solved, but some newer models have offset blades that sit closer to the edge of the machine, or they have an overhanging section that extends past the wheels, so it can cut right to the edge when the robot mower turns. There are even robot mowers with built-in trimmers and other garden tools, though I’ve yet to test one.
While edge cutting is getting better, I still find that most robot mowers need some adjustment to reliably cut the entire lawn. I often have to edit the map or tweak sensitivity to ensure they cut all the way to the edge, yet there are still areas that they seem to miss. Plants, shrubs, and trees that overhang the lawn cause issues, as robot mowers, understandably, err on the cautious side when it comes to potential obstacles. There’s still room for improvement here.
Smart Finish
While the first robot mower I tested churned my lawn into a muddy mess, most robot mowers now have some form of rain detection, so you can set them not to cut if the grass is wet. The latest models are also far better at handling wet grass and turning without skidding or churning up a big chunk of your lawn.
Some robot mowers offer customization in terms of the lawn finish you want. You may find an option in the app for Wimbledon Stripes (dark and light stripes), achieved by mowing rows in opposite directions. Some mowers can even do spirals, checkerboards, and other patterns.
I know I’m giving it the hard sell here, but robot mowers are just like robot vacuums. Once you start using one, you never go back. Robot vacuums aren’t perfect either, but they significantly cut down your chore time, and that’s what you can expect from a robot mower. That said, they can be awfully pricey at the top end, and most of the cheap mowers I’ve tried are still pretty terrible, though the midrange is improving fast.
Last summer was the first cutting season I got through with no major mower mishaps. I didn’t really think about my lawn at all. If you have a big lawn, not enough free time, and relatively deep pockets, robot mowers are an investment you won’t regret.
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