A robot mower will keep a lawn cut to a consistent height without you touching it, but the right model depends almost entirely on one decision: how it knows where the edge of your lawn is. The three approaches on sale are buried boundary wire, satellite-based GPS or RTK navigation, and camera vision. Each suits a different garden and budget, and choosing the wrong type is the most common and most expensive mistake buyers make. Expect to spend anywhere from around £500 (about $630) for a small wire-based model to £2,000 (about $2,500) or more for a wire-free machine that handles a large, complex garden.
The reason robot mowers produce such a healthy lawn is the way they cut. Rather than removing a third of the leaf once a week, they trim a tiny amount every day or two with small razor blades, and those clippings are so fine they fall back into the sward and break down within hours. This is grasscycling taken to its logical end: the lawn is fed a steady trickle of nitrogen from its own clippings, and because the grass is never shocked by a hard cut it stays in constant active growth, which thickens the sward and crowds out moss and weeds. The trade-off is that the finish is uniform rather than striped, since there is no roller pressing the grass into light and dark bands.
Boundary Wire Models: Proven and Affordable
The established design uses a thin perimeter wire pegged around the edge of the lawn, just on the surface or buried a few centimetres down. The wire carries a low-voltage signal that the mower senses, so it knows to turn back when it reaches the boundary. Within that loop it mows in a random or systematic pattern, returns to its charging base when the battery runs low, and resumes automatically. Entry models such as the Worx Landroid M cover around a quarter of an acre (roughly 1,000 square metres), and the larger Landroid L handles about half an acre, with prices commonly around £600 to £900 (about $680 to $1,150).
Wire systems are reliable and the cheapest way in, and they cope well with simple, well-defined lawns. The drawbacks are the install and the maintenance. Laying the wire takes an afternoon, and once it is down a careless spade, a digging dog or a scarifier can break it, after which the mower stops working until you find and repair the break. For a simple rectangular lawn under half an acre, though, a wire-based machine remains the best value and the least likely to be confused by its surroundings.
Wire-Free Navigation: GPS, RTK and Vision
Newer machines drop the wire entirely. GPS and RTK models use satellite positioning, with RTK adding a small fixed base station that corrects the signal to centimetre accuracy, so you define the lawn boundary once in an app by walking the perimeter or drawing it on a map. The Worx Landroid Vision Cloud, for example, covers up to an acre using this kind of positioning and sells for around £1,500 to £1,800 (about $1,840), while Husqvarna offers wire-free Automower models across a range of garden sizes. The appeal is obvious: no wire to lay, no wire to break, and easy changes to the mowing area through the app.
Vision models instead use onboard cameras to recognise grass against paths, beds and obstacles, steering by what they can see. This works well in good light and clear conditions and avoids both wire and satellite dependence, though dense shade, low sun and unusual layouts can challenge it. RTK and vision systems carry a price premium and need a reasonably open sky or clear sightlines to work at their best, so a garden boxed in by tall trees or buildings can actually suit a humble wire model better than an expensive satellite one. The honest picture across the market is that for most gardens under half an acre with simple boundaries, a wire-based or entry GPS machine gives excellent value, while larger or more complicated plots are where the wire-free premium starts to pay off.
Matching a Mower to Your Garden
Start with area and slope. Every model lists a maximum lawn size and a maximum gradient, usually somewhere between 35 and 45 percent, and exceeding either leaves grass uncut or the mower stranded. Measure your lawn and be honest about the steepest bank. Next consider the shape: narrow passages between lawn sections, lots of flower beds, and tight corners all favour a machine with good obstacle handling and, ideally, app-defined zones. Look for a rain sensor if you would rather the mower sheltered during downpours, and check the anti-theft features, since these machines are portable and valuable. Most include a PIN lock and an alarm, and GPS models can be tracked and disabled remotely if moved.
Running costs are modest. The cutting blades are small consumables that cost a few pounds or dollars and need swapping every couple of months in the mowing season, and the battery is good for several years before it needs replacing. Set realistic expectations on edges, too: robot mowers cannot cut right up to a wall or fence, so you will still need to trim the very perimeter occasionally with a strimmer or shears. The mistake to avoid is buying purely on the headline lawn-size figure. A machine rated for your area but unable to climb your slope, or a wire-free model under a heavy tree canopy that blocks its signal, will disappoint no matter how large a lawn it claims to handle. Match the navigation type to your actual garden first, and the size rating second, and a robot mower will keep the grass in better condition than most weekend mowing ever achieves.
Setting up the first cut is where patience pays. With a wire model, peg the boundary loosely first and run the mower around to check it turns where you expect before burying or fixing the wire permanently, since adjusting a buried wire is tedious. With an app-defined GPS or vision machine, walk the perimeter slowly and add no-go zones around ponds, beds and tree roots before you let it run unsupervised. Start the mowing height higher than you think you need and lower it over a week or two, because dropping a long lawn straight to a low setting stresses the grass and overloads the small blades.
Living with a robot mower means planning for the edges, the off-season and safety. The machines cannot reach right up to walls, so keep a strimmer for the perimeter, and on lawns with children or pets choose a model whose blades stop the instant it is lifted or tipped, which all reputable machines now do. Over winter most owners bring the mower and its charging base indoors, clean off the season’s grass, charge the battery to around half and store it somewhere frost-free, since a battery left flat in a cold shed degrades quickly. Factor in that the cutting blades are consumables to replace every couple of months in the growing season, and the lawn will reward the routine with a consistently even, thick finish.
Cost over time is the figure most buyers overlook. A robot mower is a larger outlay than a push or ride-on machine, but set against several seasons of weekend mowing, fuel or the cost of a contractor it can pay for itself, and the lawn ends up in better condition from the constant light cutting. Running costs come down to electricity for charging, which is small, a set of replacement blades every couple of months in the growing season at a few pounds or dollars, and a battery that lasts several years. Against that, weigh whether you actually enjoy mowing; some gardeners are happy to hand the chore over entirely, while others miss the stripes and the satisfaction of a job done by hand, which no robot can give you.
