International Blog How cleanly does a robotic mower cut the lawn edge?

How cleanly does a robotic mower cut the lawn edge?

04.05.2021
With the purchase of a robotic mower, garden owners actually hope for a complete handover of lawn care to their new garden helper. Unfortunately, the edges of the lawn quickly become a nuisance when the robot leaves a small strip that has to be manually trimmed. However, there are methods to ensure that lawn edges are also mowed cleanly.

A robotic mower reduces the time spent on lawn care to an absolute minimum. Not only is the need to mow the lawn eliminated, but maintenance work is also usually less than with a classic gasoline mower. If it weren't for the lawn edges, there would be no manual retouching with a lawn trimmer or shears. Moreover, the overall appearance is not very neat if blades of grass sprout uncontrollably along the edges of the lawn. Never fear- there are ways to minimize retouching.

Why does an edge remain with robotic mowers? 

The fact that robotic mowers simply do not mow a lawn to its very edge is mainly due to safety measures built into the device. The razor-sharp blades are well protected under the device and stop automatically when lifted to avoid any possible contact with an obstacle. It's also clear that the blades don't reach the outermost edge of the casing because the risk of injury alone would be too great.
How wide the strip at the edge of the lawn will be, depends on the distance between the blades and the housing. If the blades sit in the center, this can be quite large (around 10-20 centimeters). In models with an edge-cutting function, the strip at the edge of the lawn is considerably narrower (6 centimeters). That sounds like a lot at first, but it's no different than with classic lawn mowers. Here, too, a small strip remains in each case, where manual retouching is necessary.

Robotic mowers with edge-cutting function

Most robotic lawnmowers merely do not reach edges based on their design: blades are mounted centrally under the device. There is a gap between the blade and the housing, which is particularly noticeable when the robot drives along a wall. It is not uncommon that a strip of about 10-20 centimeters remains with a robotic mower. The size of the strip increases with the size of the robot and the distance of the perimeter wire to the edge also plays a significant role.
The blades of robotic mower with an edge-cutting are not mounted centrally but rather laterally under the device and even protrude beyond the wheelbase. Also, there is a small distance to the outer edge of the housing for safety reasons alone. However, this is limited to a much smaller width of about 6 centimeters so that the lawn edge is cut quite cleanly. The robotic lawnmower always plans its route in such a way that it cuts the edges with the blade side. 


A clean lawn edge can be achieved by laying a row of stones along walls so that the lawn does not grow right up to the wall. This will ensure a small passable strip for the robotic lawnmower.

The correct laying of the boundary wire is important


For robotic lawnmowers with an edge-cutting function, it is especially important to make sure that the perimeter wire is accurately laid. If you lay the wire too far inwards, it will not be possible for the blades to reach the lawn edge. The ideal distance of the perimeter wire to the lawn edge, walls or fences can be found in the manufacturer's manual. Some models also come with a ruler to make installation easier.
For paths that can be driven over, no wire boundaries are required. The robot simply drives over them and mows the edges automatically.

Lawn edge stones for the perfect edge cut

Not all robotic lawnmowers have the practical edge-cutting function. However, with a little trick, lawn edges can be cut perfectly even with models where the blades are mounted centrally. Having said that, this requires either a well-planned garden design or some retouching. 
To do this, place a boarder of stones around lawns and flower beds. These should be placed at ground level and easily passable for the robotic lawnmower. Lay the boundary wire as close as possible to stones. This will allow the robot to drives over them with one wheel while the centrally-positioned blades reach the lawn’s edge.


Alternatively to stones, you can also use boarders along flower beds made of wood, metal or plastic - or simply leave the front edge of a flower bed free of vegetation so that the robot can use soil or compost to navigate the surface. However, in this case, regular trimming along the edge is necessary so that the lawn does not grow into the bed.
If you are using a robotic lawnmower that works with sensors instead of a perimeter wire, bed edgings are necessary to provide a clear contrast between the lawn and the beds. Of course, you can simply form a natural barrier that the robot cannot drive over.

Manual finishing with the lawn trimmer

If you do not plan on converting your garden and you don’t purchase a robotic lawnmower with an edge-cutting function, the only other option is to manually trim your lawn or use (at best: battery-powered) lawn shears. Both are not particularly complex or strenuous but will cost you more time. In addition, you will be required to purchase more garden tools. 

Other features for neat lawn edges

The edge-cutting function is one thing. The other is a robotic mower that achieves an overall perfect cutting pattern. 

  • The most important criterion here are permanently sharp blades that really cut the lawn cleanly and not just snap off the blades of grass. The result is frayed grass tips that tends to turn brown. Sooner or later, your lawn will no longer look lush, green and healthy.
  • It is also helpful to have an oscillating, suspended mowing deck which ensures an clean cut even if the terrain is not completely level everywhere. 
  • Always have the perfect grip even on bumpy edges. Wheels with particularly good traction are recommended.

Robotic lawnmowers with an edge-cutting function mow the edges cleanly to within a few centimeters but also reach their limits when the vegetation reaches right up to walls and fences. To avoid any kind of retouching, it is therefore advisable to trim the lawn with a boarder of about 6 centimeters to the outermost edge. This will give you amply time to enjoy your perfectly manicured garden.

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