Robot Mowers for Narrow Passages

Many gardens are not one lawn but two, joined by something narrow: a path down the side of the house, a gap in a hedge, a gateway. Whether a mower can drive through that gap decides whether it can mow the whole garden or only part of it.

Measure the narrowest point first

Measure the narrowest point of the passage, at ground level, including anything that overhangs — a fence post, a downpipe, an overgrown shrub. That is your working width.

Then compare it against the mower's overall width. Not its cutting width: its body width, which is always greater.

As a general rule, a mower needs meaningful clearance on both sides rather than a millimetre-perfect fit. A passage that is only very slightly wider than the machine will work in a laboratory and fail in a garden, where positioning drifts by a few centimetres and grass grows in from the edges.

Why positioning accuracy matters here

To drive down a corridor, a mower must know where it is with an accuracy considerably better than the width of the corridor. This is where the navigation technology becomes decisive.

• RTK positioning is accurate to centimetres in the open — but a narrow passage is very often between two buildings or walls, which is precisely where satellite reception is worst. This is a genuine irony of the technology: the place it is most needed is the place it works least well.
• LiDAR is well suited, because walls and fences are exactly the features it navigates by.
• A boundary wire through the passage is completely dependable, and remains the simplest solution for a difficult corridor.

Practical approaches

Widen the passage if you can. Cutting back an overgrown hedge by 15 cm is often easier than buying a different mower.

Lay a wire through the passage even on an otherwise wire-free system, if the model supports a guide wire. Some do.

Treat the areas as separate zones and accept carrying the mower between them, if the passage is genuinely too tight. It is less convenient, but it is honest about the constraint.

Use two mowers on a larger property. If both areas are big enough to justify it, a mower each removes the problem entirely.

Surface matters too

A passage is often paved rather than grassed. Most robot mowers can cross a hard surface, but check:

• Is there a kerb or step? Most models manage only a small step, and a raised edge can stop a mower dead.
• Is the surface slippery when wet — smooth paving or decking? Traction on a wet slab is much worse than on grass.
• Is there a drain or gully the wheels could drop into?

What to check before you buy

• What is your narrowest clearance, measured at ground level with overhangs included?
• What is the mower's overall body width, not its cutting width?
• Is there sensible clearance on both sides, rather than a tight fit?
• Is the passage between buildings, where satellite reception will be poor?
• Is there a step, kerb or slippery surface along the route?