I used a robot lawn mower for a month: here's what surprised me

I've been the scientific adviser on our robot lawn mower lab tests since we started testing them back in 2020, but I've not set one loose in my garden before. 

Getting hands-on with the Ecovacs 0800 RTK robot lawn mower was an interesting experience, from training it up to letting it freely roam around my lawn for a month.

Through trial and error I found out why it's important to consider the cutting height, the slopes and layout of your garden, as well as the potential need to introduce no-go zones for any immoveable hazards or obstacles.

Here's my main takeaways from using a robot lawn mower, in case you're considering investing in one.

Find out how the Ecovacs 0800 RTK scored in our tests and compare it to the other 22 mowers we've tested in the best robot lawn mowers

Before you get started

Before you hand over your cash, make sure you spend time assessing your garden’s size and layout to ensure you buy the right robot lawn mower for your garden. 

A small robot mower may need multiple trips out to cut the whole area, making it less efficient than doing it yourself. And a mower that’s too big for a small garden will take up unnecessary space and look out of place.

Our reviews tell you the recommended lawn size for each mower and it's capacity to handle slopes. Most robot lawn mowers we’ve tested can cope with slopes between 25-45%, although one can manage particularly steep slopes of 80%.

The robot mower I used was perfect for my garden. It cut the whole lawn on one battery charge, and it coped well with the slight slope and bumpy surface of my new-build plot.

It didn't need a boundary wire, but for models that do, you’ll need to factor this in so you know how much wire you’ll need.

Another thing to think about is where the robot will sit when it’s not trundling around your lawn. The charging station must be plugged into an electrical outlet, so if you don’t have an outside socket you’ll need to find a suitable location. 

How to train your robot lawn mower

Most robot lawn mowers that we’ve tested are fairly easy to set up, but we’ve seen some that are trickier than others. 

Traditionally, robot lawn mowers have a boundary wire to stop them straying, but the one I tried uses GPS/RTK to map out the lawn, which means that no wire is necessary. 

RTK stands for 'Real Time Kinematic' positioning, and it's used to enhance the GPS satellite signals to provide greater resolution and more accurate positions. 

This meant that I had to install a reference station in addition to the charging station. Looking a bit like a UFO, it helps the mower receive enough satellite signals across the whole garden and enhances the accuracy.

To teach the robot mower what space it needs to cut, I had to drive it around the perimeter of my lawn following the instructions on the app. These were really easy to follow, and showed the outline as I moved around. 

Driving the robot took a bit of getting used to – it felt a bit like driving a remote control car – but the handy 'backtrack' feature made it easy to re-do a section if I wasn't happy with it.

While the robot mower had some basic controls on its panel, I found the app really easy to use. Once the perimeter had been set, it was a simple matter of sending the robot out for the first cut. 

The app showed the progress throughout, using a handy colour-coded map to show where had been cut and where hadn’t, and the remaining battery life. Once the robot had finished, it took itself back to the charging station automatically.

The good news is that once you’ve told your robot mower where to cut it can find its way there by itself, even if that means navigating across a patio.

Cutting height is important – it’s not like a normal lawn mower

If you’re used to a standard lawn mower, it’s important to bear in mind that robot mowers work slightly differently, so you’ll need to adjust how you approach cutting your lawn.

Standard lawn mowers work by collecting the grass clippings in a box or bag on the mower, which you then empty into your green waste bin or compost heap. Robot mowers, however, are smaller and don’t have built-in collection capabilities. They leave the clippings behind on the grass, which is a process known as mulching. 

There is the temptation, especially if you haven’t cut your lawn for a while, to cut it short by lowering the cutting height. However, as I found out, if you do this with a robot mower you’ll be left with long, unsightly clumps of grass cuttings sitting on your lawn. 

Mulching is intended to enrich your lawn as the cuttings break down, but those long cuttings will take a long time to disperse and may end up suffocating the grass instead of enriching it.

So take it slow, lowering the cutting height little by little until you have a length you’re happy with. 

One of the benefits of autonomous cutting is that you can schedule the mower to cut as often or as little as you like. So even if you’re only taking the tips of the grass blades off each time, this enables you to keep the grass at the length you like with less effort than getting a standard lawn mower out multiple times.

Avoiding obstacles

Let’s face it, any lawn mower will come across obstacles in the garden – walls, fences, washing line poles, flower pots and in my case, my son's toys.

Like many newer models, the robot mower I used has a camera on the front for identifying obstacles. You can watch the camera feed through the app, giving you a robot mower-eye view of the garden, which we found entertaining.

Like any lawn mower, it struggled to get up close to edges, such as the wall encasing one side of my garden. 

And there are some areas that it just couldn’t cut, such as around the steps of my son’s playhouse, so those will still need tackling with a grass trimmer or shears.

While it took a little longer than I expected to detect my feet (don’t worry, I still have all my toes), it gave other obstacles, such as a stray football left behind by my son, and his swingball pole, a much wider berth. 

The robot simply adjusted its travel route to account for these, and carried on cutting the rest of the lawn.

There are three drain covers in my garden, and while two of them are flat to the ground and presented no problem to the robot mower, the third proved slightly problematic. 

One side of it is flush to the ground, but thanks to the slight slope of my garden, the other side protrudes by a few centimetres. 

After the mower made a couple of attempts to mount this drain cover, I decided it was best to set this as a 'no-go' zone and used the app to switch the robot into training mode and drive it around the drain cover. 

This teaches it not to go inside that zone, removing the risk of damage to both robot and drain cover.

What I liked and didn’t like

I liked:

• How easy to set up and programme it was. Driving the robot mower around the garden only took a few minutes, and meant that it would cut exactly where I wanted it to.
• Setting up a schedule so that the robot goes out when I wanted without having to set it going myself. It's handy if you have a large lawn or multiple areas to cut, or want to avoid cutting at certain times, such as when children, pets or nighttime visitors are using the garden.
• Once set up, the robot mower was pretty autonomous, following the schedule I set up or being sent on its way at the push of a button.
• It was surprisingly quiet. The only noise was the snip of the blades of grass being cut. One of my neighbours cut their grass at the same time as the robot mower was running, and it was easily drowned out. So I could sit in the garden enjoying a cup of tea and not be disturbed by it. 

I didn’t like:

• While this robot managed to cut my whole lawn on one battery charge, it took 2 hours and 45 minutes to charge. This wasn’t a problem for me, but may be an issue for those with larger gardens.
• Although robot mowers can run overnight, it's better to use them during the day because they are known to injure or even kill small nocturnal animals like hedgehogs and voles when they cross paths.
• Autonomous mowing sounds easy and hassle-free, but in my garden, at least, it isn’t a complete solution. Due to the layout, there were some areas that the robot mower just couldn’t cut. So some manual work is still required with a grass trimmer or shears.

Would I buy a robot mower?

I was very impressed with the robot mower I tried out, and would definitely consider buying one in the future. 

But our cordless lawn mower is still going strong and our lawn isn’t so big that we struggle to look after it. 

I would also need to find a better place for a robot mower to live, likely by installing a new outdoor electrical socket in a suitable place. Robot mowers can be expensive, but we’re starting to see more budget options, so it’s definitely something I’ll be keeping an eye on.