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Quick answer
Every robot mower leaves some grass uncut along a raised edge like a fence or wall, because its blades sit inside the body. Independent reviewers have measured strips of about 3 to 5 inches on typical models. Three designs get much closer: the Ecovacs GOAT A3000 LiDAR PRO adds a built-in string trimmer (Ecovacs states about 0 cm), the Dreame A3 AWD Pro swings its cutting disc out to under 3 cm (about 1.2 inches), and the Mammotion LUBA mini 2 AWD uses a side disc that sticks out past the body. The catch is that edge cutters often run at a fixed height. And along a path or patio that’s level with the lawn, most wire-free mowers can drive onto the paving and leave no strip at all.
The uncut fringe is the most common complaint from new robot mower owners. The lawn looks perfect in the middle and shaggy around the edges: along the fence, around the flower beds, against the house. A robot mower saves you from mowing, but if you’re still out every week with a string trimmer, it’s only done half the job.
This guide explains why the strip exists, what reviewers have measured, which mowers get closest, and the one cheap landscaping fix that solves most of the problem. MowReview quotes no prices and hasn’t tested these mowers. How we research explains why.
Why robot mowers leave a strip
There are two reasons, and they add together.
- The blades are inside the body. For safety, the cutting disc sits well inside the mower’s shell, so the blade can’t reach the ground right beside a wall. Robomow, a robot mower maker, puts the distance from blade to the outer edge of the housing at between 6 cm and 20 cm depending on the model. Ecovacs says the same: the gap between the blade and the outer edge of the mower is what leaves the strip.
- You tell it to keep its distance. A mower that drives right up to a fence will bump into it. So you set a border distance. Worx recommends at least 15 cm (about 6 inches) from fences raised above the ground. For wired Automowers, Husqvarna’s manual puts the boundary wire 35 cm (14 inches) from obstacles taller than 5 cm.
Husqvarna is candid about the result: “you may need to complement the edges with a trimmer.” And after several years of reviewing robot mowers, a Tom’s Guide reviewer still uses a string trimmer “to touch up areas around the borders.”
Flush edges vs. raised edges
This is the distinction that matters most, and most spec sheets skip it.
| Edge | What happens |
|---|---|
| Paving, path or patio level with the lawn | A wire-free mower can drive onto it and cut the grass edge fully. Ecovacs calls this cross-boundary mowing and states 0 cm left. |
| Wall, fence, raised bed edging or a step | The mower has to stop short. The blade inset plus the border distance leaves a strip. |
| Flower bed with a soft, dug edge | Usually treated as a raised edge, because the mower can’t drive into the bed. |
So before comparing mowers, walk your lawn and note which edges are flush and which are raised. If most of yours are flush, almost any wire-free mower will do well. If most are fences and walls, the closest-cutting models below are worth paying attention to.
How close each mower gets
| Mower | Distance left | Source |
|---|---|---|
| Ecovacs GOAT A3000 LiDAR PRO (trimmer) | About 0 cm stated | Ecovacs |
| Dreame A3 AWD Pro | Under 3 cm (about 1.2 in) stated | Dreame; Basic Tutorials review confirmed under 3 cm |
| Ecovacs GOAT A2500 RTK | 1.97 in stated | Ecovacs |
| Ecovacs GOAT A3000 LiDAR (no trimmer) | As close as 2 in stated | Ecovacs |
| Ecovacs GOAT A3000 LiDAR PRO (blade only) | 5 cm (about 2 in) stated | Ecovacs |
| Worx Landroid Vision | About 8 to 10 cm (3 to 4 in) along a fence or wall | EasyLawnMowing |
| Segway Navimow X3 (no trimmer) | About 9 cm (3.5 in) | Notebookcheck |
| Dreame A1 Pro | At least 12 cm (4.7 in) where it can’t drive over the edge | Notebookcheck |
“Stated” figures are the manufacturer’s own. Reviewer figures come from hands-on testing by the outlets named.
The picks
Closest edge: built-in string trimmer
Ecovacs GOAT A3000 LiDAR PRO
- Stated edge distanceBlade 5 cm; trimmer about 0 cm
- TrimmerString line, 18 cm cutting width
- Stated cutting height1.2 to 3.5 in
The PRO versions of Ecovacs’s LiDAR mowers, launched in the U.S. in February 2026, are, Ecovacs says, the first robot mowers with a string trimmer built in. After mowing, the trimmer head spins string line along the edge to take out the strip the blades can’t reach. Gear Diary’s reviewer said it “gets closer than any robot mower we’ve used,” and Techaeris estimated it removes “about 90 percent of manual weed-eating cleanup” on lawns with defined boundaries.
Good for
- Lawns bordered mostly by fences, walls and raised beds
- Owners who want to put the string trimmer away for most of the season
Less good for
- Quiet neighborhoods: Ecovacs rates the trimmer at 82 dBA, against 62 dBA for mowing
- Zero trimming: Gear Diary still went round some edges afterward, and Techaeris found rebuilding the empty string spool “requires some serious initial patience”
- Standard St. Augustine: its stated range stops at 3.5 inches
Closest blade edge, for short-cut lawns
Dreame A3 AWD Pro
- Stated disc-to-edge distanceUnder 3 cm (about 1.2 in)
- Stated cutting height1.2 to 3.9 in
- Drive and slopeAll-wheel drive, 80%
Dreame’s EdgeMaster design extends the cutting disc sideways at the edges, and the company states a disc-to-edge distance under 3 cm. Basic Tutorials’ hands-on review confirmed it gets “quite close to edges” and said “little reworking is necessary.” Freshly Charged found it needed “substantially less string trimmer follow-up work” than most competitors. It’s also all-wheel drive with an 80% slope rating, so it suits hilly lots too.
Good for
- Lawns cut at about 1.2 inches, such as bermuda and zoysia
- Hilly or rough lots that also need close edges
Less good for
- Taller-cut lawns: Freshly Charged found the edge cutter is fixed at 1.2 inches and will “scalp the perimeter” if the lawn is cut higher
- Quick setup: both reviews found automatic mapping unreliable, and Basic Tutorials hit firmware update problems
- Carrying: Basic Tutorials puts its weight at almost 24 kg (about 53 pounds)
Side disc that reaches past the body
Mammotion LUBA mini 2 AWD
- Edge cutterAbout 12 cm (4.7 in) side disc
- Stated max slope80%
- Stated coverage (1000 model)About 0.25 acre
A compact all-wheel-drive mower with a separate side cutting disc that extends beyond the main body, so it can reach the grass along an edge the main blades can’t. EasyLawnMowing’s review, of the UK version, found it “dramatically reduced or eliminated trimming in many areas,” and that in places it left the reviewer with “effectively no trimming.” Mammotion’s U.S. store sells replacement side discs for this model.
Good for
- Small, busy lawns with lots of beds and borders
- Lawns kept at about 2 inches, the side disc’s fixed height
Less good for
- Very short lawns: EasyLawnMowing says the side disc is fixed at 50 mm (2 inches), so the edge can end up taller than the rest
- Spread-out lots: EasyLawnMowing found the first zone must be within 5 meters of the charging station, and zones more than about 50 meters apart are impractical
- Frequent carrying: EasyLawnMowing calls it “fairly heavy”
The fixed-height catch
Edge cutters are often a separate part from the main blades, and some run at one fixed height you can’t change. Freshly Charged found the Dreame A3 AWD Pro’s edge cutter fixed at 1.2 inches, which scalps the edge of a lawn cut at 3 inches. EasyLawnMowing found the LUBA mini 2 AWD’s side disc fixed at 2 inches, which leaves the edge taller than a lawn cut at 1 inch. Husqvarna’s EdgeCut disc, sold on some models outside the U.S., is fixed at 45 mm (1.77 inches). Before you buy for the edge feature, check that its height is close to the height you’ll mow at. St. Augustine owners, cutting at 3.5 to 4 inches, should be especially careful.
The fix that works with any mower: a mowing strip
A mowing strip is a row of pavers, bricks or concrete edging laid level with the soil between the lawn and a bed, wall or fence. The mower’s wheels ride onto it, so the blades reach the last of the grass. It turns a raised edge into a flush one.
| Situation | Guidance | Source |
|---|---|---|
| Beside a flower bed | Level, ground-level stones; about 10 cm (4 in) is often enough | Robomow |
| Against a wall or fence | 20 cm (8 in) or more | Robomow |
| Wired Automower beside paving | Paving at least 12 in wide lets the mower cut fully alongside it with the Drive Past Wire setting | Husqvarna |
Two details make or break it. The strip must be level with the soil, not raised, or it becomes another edge to stop at. And with a wire-free mower, you need to draw the map boundary onto the strip, not along its inside edge, so the mower actually drives on it. How to set up a robot mower covers editing boundaries, and boundary wire vs. wire-free explains how each type handles edges.
Edge-mowing settings worth knowing
- Frequency. Worx recommends running edge cutting no more than twice a week on the Landroid Vision. Segway says its i-series mows the edges at the start of every task.
- Keep edges short enough to see. Worx says to keep grass and edges under 9 cm (about 3.5 inches) so the Vision’s camera can recognize the boundary.
- Border distance. Set it as small as your edge safely allows. Too tight against a fence and the mower will scuff it. Too loose and you’ve made the strip wider yourself.
Narrow passages and side yards are the other place edges pile up. Robot mowers for narrow side yards covers those. A pool deck is the one edge where you want a wider gap, not a narrower one: see robot mowers for yards with a pool. And if your edges are lumpy as well as overgrown, robot mowers for bumpy lawns covers leveling.
Questions
Why does my robot mower leave an uncut strip along the edge?
Because the blades sit inside the mower’s body, for safety, so they can’t reach the ground right next to a wall or fence. You also set a border distance so the mower doesn’t hit raised edges. Worx recommends at least 15 cm (about 6 inches) from elevated fences, for example.
How close to the edge can a robot mower cut?
It depends on the edge. Next to paving that’s level with the lawn, most wire-free mowers can drive onto it and cut fully. Along a wall or fence, reviewers measured about 9 cm (3.5 inches) on the Segway Navimow X3 and 8 to 10 cm on the Worx Landroid Vision. Dreame states under 3 cm for the A3 AWD Pro, and Ecovacs’s A3000 LiDAR PRO adds a string trimmer it says reaches about 0 cm.
Is there a robot mower with a built-in string trimmer?
Yes. Ecovacs’s GOAT A3000 LiDAR PRO and A2000 LiDAR PRO have a built-in trimmer head that spins string line to cut along edges. Reviewers found it removes most, but not all, of the manual trimming, and Ecovacs rates it much louder than mowing: 82 dBA against 62 dBA.
Will a robot mower’s edge cutter scalp my lawn?
It can if its height doesn’t match your lawn. Some edge discs run at a fixed height: Freshly Charged found the Dreame A3 AWD Pro’s edge cutter is fixed at 1.2 inches and scalps the perimeter of a taller-cut lawn, and the LUBA mini 2 AWD’s side disc is fixed at 2 inches, according to EasyLawnMowing.
How wide should a mowing strip be for a robot mower?
Robomow says level, ground-level stones about 10 cm (4 inches) wide are often enough, and recommends 20 cm (8 inches) or more where the strip runs against a wall. For wired Automowers, Husqvarna says paving at least 12 inches wide lets the mower cut fully alongside it.
Will I still need a string trimmer with a robot mower?
Probably, but much less. Even with the closest-cutting models, reviewers still did some touch-up around fences, trees and corners. A level mowing strip along beds and walls removes most of the remaining trimming.
The short version
The uncut strip comes from blades set inside the body plus the distance you keep from raised edges. Along flush paving, most wire-free mowers leave nothing. Along fences and walls, typical models leave 3 to 5 inches. The GOAT A3000 LiDAR PRO’s built-in trimmer gets closest, the Dreame A3 AWD Pro’s extending disc suits short-cut lawns, and the LUBA mini 2 AWD’s side disc works well on small lawns kept near 2 inches. Check any edge cutter’s height against your mowing height, and lay a level mowing strip wherever you can. It’s the cheapest upgrade a robot mower lawn can get.
Edges are one test. Check the others.
Lawn area, slope and trees decide the rest of the shortlist.
