Do robot mowers cut right up to the edge of the lawn?

Rarely all the way. Most robot mowers have a single cutting disc set in the middle of the body, so there's a strip between the blades and the outside of the mower. Where the lawn meets a wall, fence or flower bed, that leaves a band of uncut grass to trim with shears or a strimmer.

How wide the strip is depends on the design and the edge:

• Flush edges such as paving laid level with the lawn are the easy case. Many mowers, wired and wire-free, can run with one wheel on the paving so the disc reaches the edge of the grass.
• Walls, fences and raised beds are harder, because the mower can't overlap them.
• Edge-focused designs get closer. Mammotion fits a separate edge disc to the Mammotion LUBA mini 2 AWD and claims about 5 cm from walls; Segway Navimow claims a similar distance for the Segway Navimow H2 Series and Segway Navimow X4 Series. These are manufacturer claims, and a fixed-height edge disc may leave a slightly different finish from the main cut.

A popular fix is a mowing strip: a row of bricks or slabs laid flush along beds and walls so the mower can ride along it. It also stops the edge being churned by wheels. The RHS has advice on maintaining lawn edges if you want to keep them crisp by hand.

When you compare models, look for an edge-cutting mode and any published distance to the edge, and treat a "zero edge" claim with caution unless the manufacturer explains what it means.