Robotic Lawn Mowers: Are They Worth It?

Does anyone out there actually enjoy mowing the lawn? Thought so.

As you may have heard, you can now get a robot to do it. And not just any robot: A unit that looks like a sleek mini race car and roams your lawn while you sit back on the patio enjoying a cold drink. Or even while you sleep.

Is it worth it to pay the four-figure price tag of most top-rated robotic lawn mowers? Perfectionists might wonder if they can trust something that resembles a tiny Lamborghini to trim every blade to the exact height they prefer. These machines mow in a random pattern (much like Roombas), so you won’t get those nice straight lines that inspire pride in some property owners. But lawn mower reviews in consumer publications and websites (Wired, Wall Street Journal, Consumer Reports) indicate robots perform pretty well.

Read on to have your questions answered.

How do robotic lawn mowers work?

Powered by rechargeable batteries, either lead acid (like a car battery), lithium-ion, or nickel cadmium, the units come with a charging station that you plug into an outdoor outlet. When the battery gets low or the mower has completed its stint, the machine makes its own way back to the charger. The mowers consume very little energy compared to a gas-powered model, and release no harmful emissions.

How do you keep a robotic mower from wandering off?

The mower comes with a reel of low-voltage wire that you set around the perimeter of the area you want mowed. That creates an invisible fence to keep your mower within the boundaries. Depending on the size and configuration of your property, it’ll probably take you half a day to get the wires set up.

What if I have a lot of flower beds?

You can use the boundary wire to make any part of your property off limits to the mower, such as flower beds, shrubs, sheds, paths, and patios.

And if the mower hits a tree?

When the machine encounters any kind of obstacle, it will stop and change direction. You can also set boundary wire around a tree. Some units have sensors that detect obstacles before they run into them, and move away.

Can I use a robotic mower on a hilly or uneven lawn?

These machines work best on fairly flat surfaces. Most manufacturers say slopes up to 35 percent (from 15 to 20 degrees) are okay, but the steeper the grade the more quickly the battery will run out. And since robotic lawn mowers’ wheels can get caught in holes or small depressions, you’ll need to fill those in (and train your dog not to dig), or set boundary wire around the areas. Some mowers can maneuver themselves out of a hole by moving back and forth.

Do I still need to rake the lawn after it’s been mowed?

Not if you program your mower to run several times a week, or even daily. That way, the clippings will be fine enough to settle into the grass to decompose (and fertilize the soil). You can also adjust the cutting height to keep the grass short.

How do I choose the mower that’s right for my property?

The main consideration is the size of your lawn. The larger mowers have a wider cutting area and cover ground more quickly. After you’ve estimated the area you want mowed, read up on the different models available for your size of property. The other issue is the slope of the land, as mentioned above. Obviously, barriers like stone walls mean that you’ll have to manually reposition the mower from one part of the yard to another, which reduces the convenience factor.

Are robotic mowers loud?

Since they run on electricity, these mowers are very quiet—the sound is comparable to that of an air conditioner. You can even run it at night without waking the neighborhood.

How do you program a robotic mower?

Some of the more basic units just have an onboard control panel, but many can be programmed remotely via Bluetooth, Wi-Fi, or smartphone.

Of course, the number of hours it will take to mow depends on the size of your lawn. The machine keeps mowing until it has covered the entire area, and will usually need to stop to recharge during that time. For a small back yard, say, around 2,000 square feet, the right-sized mower might take three hours—plus recharging time.

And what if it’s raining?

Most machines have rain sensors that send the unit back to recharge until the skies clear. You can also program your robotic lawn mower to simply continue cutting in the rain.

Are robotic mowers dangerous?

They’re designed to be safe. Whenever the machine is tilted or lifted, it immediately shuts down. And if it hits anything, the blades automatically retract before it changes direction.

What we’ve accidentally left items on the lawn?

While the mower will stop and change direction if it runs into a tree or a large item like a bike, it could chew up small toys or gardening tools left lying on the grass.

Isn’t a robotic mower easily stolen?

All these devices have some sort of anti-theft system, such as a PIN code that must be entered to get it operating. You can set Husqvarna’s Automower app to trigger an alarm whenever the mower is picked up; you have to enter the PIN code to turn off the alarm. The same app lets you track your mower’s location. Also, the mower won’t run unless it’s within its installed boundary.

Are robotic mowers hard to maintain?

The cutting blades must be replaced every few months or so, and the boundary wire can break if someone trips over it.

How much do robotic mowers cost?

That’s the catch. A basic no-frills machine starts at around $700, but most models are over four figures; they can go as high as a cool $5,000. Compare that to the $400 price tag for a variable-speed, self-propelled gas mower, such as the Honda HRR2169VLA (which gets high marks from Consumer Reports).

So are robotic lawn mowers worth it?

A Wired reviewer who tested the high-end Husqvarna Automower 450X last year wrote, “After the first week, my lawn looked OK. After two weeks, it looked much better. After a month, it looked fantastic.” The 450X, which can cover up to 1.25 acres, will set you back $3,500, but for a smaller yard you can get by with paying less.

While there’s a big initial outlay, a robotic mower will cost you less than $25 per year in operating costs. If you’ve been paying landscapers to keep your lawn looking like an emerald carpet, you’ll realize significant savings in a year or two. And won’t your neighbors thank you for that everyday fresh-mown look?

Note that robotic mowers aren’t designed to hack through tall grass; they must be used regularly so the grass won’t get out of control. If you fall behind, you’ll have to borrow that neighbor’s regular mower to get caught up before unleashing your robot again. And you’ll remember how loud and stinky it is.

Has a springtime growth spurt put your lawn back on a regular mowing schedule? Here are more options:

• 10 Easy Pieces: Riding Lawn Mowers.
• Clean Mowing: Reel Mower Roundup.
• Fields of Green: 5 Favorite Lawn Substitutes.
• DIY: Wild Lawn.
• Pros and Cons: Artificial Grass Versus a Live Lawn.