Best Lawn Edger to Use With Robot Mower: 6 Points to Check

8 min read by Jordan Ellis Updated November 11, 2026

The best lawn edger to use with robot mower for most yards is a blade edger you run a few times a season. A robot mower leaves an uncut strip along walls, beds and paths, and an edger cuts the clean line it cannot reach. Our reading is that a string trimmer alone is not enough for creating new edges, while an edger alone is not a daily upkeep tool.

The short answer

Uncut strip: a standard robot mower leaves about 10 to 20 cm (4 to 8 in) along borders, per Robomow.
Edger: cuts with a blade and can carve a new edge, which a string trimmer cannot do.
Trimmer: suits routine upkeep of an edge that already exists.
Safety: pause or dock the robot mower before you edge, and keep bystanders at least 50 feet away.

How much edge a robot mower leaves behind

A standard robot mower leaves an uncut strip of about 10 to 20 cm (4 to 8 in) along borders, according to Robomow’s edge-cutting article. The strip exists because a center-mounted blade deck cannot reach grass along fences, flower beds and pavement.

Some mowers narrow that gap. Husqvarna’s EdgeCut uses a disc at the rear of the mower, fixed at 45 mm (1.77 in), and the mower makes a sweeping turn when it reaches a boundary so the disc cuts along it. Robomow says its edge-cutting function reduces the uncut width to about 5 to 6 cm, yet it still recommends leaving a margin of about 6 cm where vegetation grows right up to walls and fences.

Our reading is that the last few centimeters are the job an edger or trimmer does in most yards. A mower with an edge function narrows the strip, but it does not remove the need for a hand tool along hard borders. For that reason, the best lawn edger to use with robot mower is the one that cuts a clean line at those borders, not the one that promises to replace the mower’s own edge function.

Edger or string trimmer: which one fits a robot mower yard

An edger suits creating and redefining an edge, while a string trimmer suits upkeep between mowing sessions. Lawnlove’s comparison states that string trimmers cut with string and edgers cut with a blade, and that edgers give a cleaner and deeper line along boundaries. The same source says that a string trimmer cannot create new lawn edges, and that edgers are used once in a while to redefine an edge, while trimmers are often used at every mowing.

Tool	How it cuts	Creates a new edge	Best use alongside a robot mower
Manual blade edger	Half-moon blade, sometimes spiked tip	Yes	Redefine borders a few times a season
Rotary edger	Rotating, spiky blade	Yes	Redefine borders where the mower stops short
String trimmer	Nylon line on a spinning head	No	Routine upkeep of an existing edge

Lawnlove says manual edgers are the best tool for cutting new edges around a flower bed or hardscape. For a yard where the mower already handles most of the lawn, that points to an edger for the borders and a trimmer for the rest, rather than one tool for every job.

Edger types and power sources to compare

Edgers come as manual tools or powered units, and powered units run on gas, battery or corded electric power, according to Lawnlove. The blade shape also differs: a manual edger has a half-moon blade, sometimes with a spiked tip, while a rotary edger has a rotating, spiky blade.

Manual: the tool for cutting new edges by hand, per the same comparison.
Battery, corded electric or gas: powered options listed for edgers. Our reading is that the power source mainly changes where and how you can use the tool, so match it to your yard.
Cord or fuel: a corded or gas edger needs its cord or fuel handled around the work area, which the Virginia Tech sheet covers under safety.

The lawnlove page gives no numeric cutting depth for either tool, and it does not state weights. Compare the depth and weight figures in each manufacturer’s specification sheet rather than assuming a difference.

Robot mower on a lawn beside a flower bed with a stone edging strip — A robot mower works along the edge of a planted flower bed.

Edging method: trench, brick, stone or wood borders

A cut trench 4 to 6 inches deep is the simplest edge, and flush bricks or pavers create a mowing strip that removes the need for a weed trimmer. Kansas State’s Johnson County Extension describes a V-shaped trench made with an edger or sharp flat spade, angled toward the bed so grass roots cannot easily cross. The K-State edging guide says that trench edge needs only one or two re-cuts during the growing season.

The border material decides how much hand work remains, and our landscape edging guide for robot mower borders covers more options. The same K-State guide lists the trade-offs:

Border	Hand trimming left (K-State)
Bricks or pavers set flush	None needed for the mower strip, since they act as a mowing strip
Cement curbing	Provides a mowing strip, but it does not allow easy expansion
Gathered stone	Hand trimming is required, because grass finds its way into the gaps
Wood set flush	Eliminates frequent hand trimming
Raised wood beside the lawn	Requires a higher level of maintenance

Our reading: a robot mower is a good match for flush borders such as mowing strip pavers, while gathered stone and raised wood still call for an edger or trimmer on a regular basis.

Virginia Tech’s extension sheet on powered hand tools cites a past study showing that string trimmers and edgers alone cause more than 4,600 injuries that need emergency room treatment each year, and about one-third of those cases are eye injuries. Its guidance is to keep bystanders, children and pets at least 50 feet from the work area, wear full eye and ear protection, and check that the edger blade is firmly attached and rotates freely. The sheet also says not to inspect, repair or service an edger while it is running.

Heads up

A robot mower runs on its own schedule. Our reading is that you should pause it in its app or return it to the dock before you start edging, so it does not move across the area you are working on.

Husqvarna’s EdgeCut support article also advises cleaning the disc guard regularly, especially in spring and autumn. That maintenance applies to the mower’s own edge disc, and it is separate from the safety rules for a hand edger.

Gardener trimming grass at a stone-edged flower bed with hand shears next to a robot mower — Hand tools finish the strip a robot mower leaves at a border.

Best lawn edger to use with robot mower: what to check before you buy

When you compare the best lawn edger to use with robot mower, start with the border type and the blade style, then match the power source to where you will use it. The list below uses the sources above, plus our reading where a source is silent.

Border type. If your borders are flush pavers or wood, a trimmer may cover upkeep. New or raised edges need a blade edger (Lawnlove, K-State).
Blade style. Compare a half-moon manual blade with a rotary spiked blade, since each cuts a different line (Lawnlove).
Power source. Choose manual, gas, battery or corded electric by yard size and by how easily you can route a cord (our reading).
Blade and guard condition. Check that the blade is firmly attached and turns freely before each use (Virginia Tech).
Cutting depth. Compare the depth figure in each manufacturer’s specification, because the comparison source gives none (Lawnlove).
Robot mower fit. Note your mower’s edge function, such as the 45 mm EdgeCut disc, to know how wide the strip is before you buy (Husqvarna).

Frequently asked questions about a lawn edger with a robot mower

Do I still need an edger if my robot mower has an edge-cut function?

Often yes. An edge-cut function narrows the uncut strip, but Husqvarna’s EdgeCut disc sits at a fixed 45 mm position, and Robomow still recommends a margin of about 6 cm where vegetation grows against walls. Our reading is that most yards keep a small amount of hand edging along the hardest borders.

Is an edger or a string trimmer better with a robot mower?

For the best lawn edger to use with robot mower, neither tool is better for every job. An edger creates and redefines an edge, while a string trimmer keeps an existing edge tidy between mowings. Lawnlove notes that edgers are used once in a while, and trimmers are often used at every mowing, so many yards use both.

How deep should an edged border be?

The K-State guide describes a trench or V-shaped ditch 4 to 6 inches deep and wide, angled toward the bed. It recommends re-cutting the edge once or twice during the growing season before grass or plants become a nuisance.

Can I edge while the robot mower is running?

Virginia Tech advises keeping bystanders, children and pets at least 50 feet from the work area, and not servicing an edger while it runs. A robot mower can start on its own schedule, so pause or dock it before you edge. That step is our reading, not a rule from the source.

Sources

Robomow edge-cutting article (manufacturer): uncut strip of about 10 to 20 cm, edge-cut width and recommended margin.
Husqvarna EdgeCut support article (manufacturer): 45 mm disc position, boundary trigger, compatible models, disc guard cleaning.
Lawnlove, string trimmer vs lawn edger (publisher, updated October 9, 2026): cutting method, creating new edges, power sources, edger types.
K-State Research and Extension, All About Edging (university extension, rev. 2022): trench depth, re-cutting, border trade-offs.
Virginia Tech BSE-97P, Lawn Care: Powered Hand Tool Safety (university extension, 2019): injury figure, bystander distance, blade and running-tool guidance.