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24 May 2022

Is it time to buy a robot mower?

They might save you time, but they can cost you a lot of money. We look at the pros and cons of robot lawn mowers

Let’s face it: sometimes, mowing your lawn is a real chore. 

It’s loud, it’s arduous, and it can often feel like a waste of a perfectly good sunny afternoon. Wouldn’t you rather be lounging on your patio, cool drink in hand, watching a little robot contentedly tour its way around your garden, leaving behind perfectly shorn grass in its wake?

If the idea of lugging your mower out of the shed fills you with dread, then perhaps you should consider investing in a robot mower. Robot mowers have been steadily rising in popularity across Europe, and although they are generally more expensive than traditional mowers, there’s certainly some value to be found in the hassle-free lawn management they provide.

However, it’s not all sunshine and roses when it comes to robot mowers – they have their downsides, too. We’ve rounded up some of the pros and cons of robot mowers to help you decide if they’re for you. Alternatively, take a look at our robot mower reviews.

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PRO: They’re incredibly convenient

A robot mower cutting through grass

As mentioned above, the biggest draw to robot mowers is their ease of use. Lawn mowers are big, bulky items, and it can be a struggle to push them around your lawn. Robot mowers, on the other hand, are small and lightweight. After completing the initial set up, you won’t be interacting with them much – most robot mowers are autonomous, switching themselves on and getting to work on a schedule set by you, before returning to their charging dock to power up ahead of the next cut.

CON: …but not entirely

Installing the perimeter wire

Almost every robot mower needs a perimeter wire installed around the garden so that it can detect the boundaries of the lawn and find its way back to its charging dock at the end of a mowing session. This is where some human intervention is required – the perimeter wire must be laid and pegged down by hand. Some manufacturers and dealers will do this for you, but it will generally cost extra. Furthermore, this wire needs to be linked to your robot mower’s charging base, which is going to need to be plugged in to an outlet. If you don’t already have a power outlet in your garden, installing one can be an expensive job.

Robot mowers also tend to struggle with navigating around obstacles like flowerbeds and ornaments, either colliding with them and causing damage, or keeping a wide berth and leaving untidy edges of longer grass. While these would be relatively easy to clean up using a grass trimmer, they do present a rude awakening to any dreams of a garden that requires absolutely zero manual labour.   

Discover the best grass trimmers

CON: They’re very expensive

Robot mowers aren’t cheap. Our Best Buy robot mower models start at £889. This is a lot more expensive than our Best Buy electric and cordless lawn mowers, which begin at £199 and £298 respectively.

Robot mowers’ high price points are due in part to their costs in research and development. As they are still fairly new to the market and have  relatively few owners, a lot of these costs are being passed on to the consumer. As the market continues to grow, we can expect the price to drop.

To get the most convenient robot-mower experience, you’re also going to have to shell out for models with fancy extra features. Things like GPS tracking, weather detection and anti-theft sensors are all great additions to robot mowers, but they come at a premium price.

PRO: …but maybe not as much as they first seem?

Whilst the initial cost of a robot mower is staggering, it becomes slightly more reasonable when you factor in the associated lifetime costs. The main running cost of a robot mower is the electricity it consumes when recharging its battery. Due to their small size, this is generally not a large amount, and is negligible in comparison to the fuel needed to run a petrol mower.

Servicing costs are also usually less than bigger mowers, as the only thing that requires regular maintenance is sharpening or replacing the small cutting blades. The lithium-ion battery will also degrade over time as it goes through charging cycles, and eventually need replacing. At Which?, we understand the importance of living sustainably, which is why we never award a Best Buy to a robot lawn mower that doesn't have replaceable batteries, no matter how good it might be. However, it is important to keep in mind that replacement batteries can be pricey themselves – sometimes over £100.

A more abstract element of the cost is how much you value the time you’d spend manually mowing the lawn, which is easier to calculate if you currently pay a gardener to do the job for you.

Learn how to find help in the garden

PRO: They’re the safest way to get a perfectly manicured garden

Short cut lawn

Lawn mowers are responsible for around 6,500 accidents in the UK per year, generally due to accidental contact with the fast-spinning blades or from debris being thrown up when mowing. Whilst robot mowers do not completely negate these risks, their collision sensors and tucked-in blades reduce them massively.

Because robot mowers don’t need to be brought out to be used, most people let them run once every few days. They are designed to cut frequently, so your lawn always looks freshly cut and manicured. Robot mowers are also mulching mowers, so there won’t be any clippings for you to deal with. Not only that, but the clippings will also actually provide the grass with nutrients, leading to a healthier and greener lawn.

Want a beautiful garden without a robot mower? Read our guide to cutting the perfect lawn

CON: …but they can be harmful for your garden’s ecosystem

The zero emissions of a robot mower are attractive from an environmentally conscious point of view, but some studies have suggested that they can have an adverse effect on the ecosystems present in your garden.  With the lawn always cut short, the grass will essentially become a monoculture. The flowers and shoots that insects rely on for food won’t be able to grow, and pollination will not occur. Perhaps more viscerally, there are also reports of hedgehogs and other small nocturnal animals being injured by robot mowers running at night.

To address these issues, we suggest that owners set the robot mower's blades on their highest setting so flowering plants, such as daisies, can still bloom and avoid using robot mowers at night. You could also establish part of your garden as an area in which wildflowers are allowed to grow and laying the boundary wire accordingly, to help insect populations and allow pollination.

Whether you decide on a robot mower or a more traditional mower, you need to find one that suits you and your garden. Different models are better suited for different lawn sizes, layouts and slopes. Thankfully, here at Which? our thorough testing programs consider all of these.

To find your perfect mower, check out our robot mower buying guide , or our lawn mower buying guide