Which Robotic Mower Trims Closest to the Lawn’s Edge?

The great thing about robotic mowers is that they just mow your lawn all by themselves. But is your mower really getting the entire lawn? Some people find that a narrow strip of grass along the edges of their lawn is always left behind after the robot does its job! If this is you, you are probably wondering which robotic mower model can trim closest to the edge. So, which robotic mower leaves the least lawn standing?

Which robotic mower has the smallest mowing edge? Robotic mowers with edge mowing mode can mow the closest to the edge. These robotic mowers include models of the ROBOMOW and WORX brands. The Landroid models from WORX leave the narrowest strip of lawn behind overall. Lawn edging stones can also be used to help prevent grass being left behind.

But how exactly does the edge mode achieve this? And how does it differ from regular mowing from a robotic mower? How exactly does it work with the lawn edging stones?

These Robotic Mowers Give the Best Edge Cut

The models which can mow the closest to the edge of a lawn are those with edge mowing function. Depending on the manufacturer, this function may also be called Cut to Edge (WORX), Edge Mode (ROBOMOW) or simply Edge Mowing (all others).

We keep lists of the different models and their capabilities on our blog. The following list contains robotic mowers that leave a less than 6-inch margin. Over time we will add more models to the list, but I cannot claim that the list is completely exhaustive.

Model	Margin
AMBROGIO L200 Carbon Blackline	8.5 inch
AMBROGIO L250i Elite GPS	6.4 inch
AMBROGIO L350i Elite GPS	4.6 inch
AMBROGIO L400	4.8 inch
AMBROGIO L60 Deluxe	4.4 inch
AMBROGIO L60 Elite	4.4 inch
AMBROGIO L85 Elite	5.2 inch
HONDA Miimo HRM310	8.7 inch
HONDA Miimo HRM520	8.7 inch
HUSQVARNA Automower 115H	6.7 inch
HUSQVARNA Automower 305	6.3 inch
HUSQVARNA Automower 310	7.9 inch
HUSQVARNA Automower 315	7.9 inch
HUSQVARNA Automower 315X	7.9 inch
HUSQVARNA Automower 430X	8.5 inch
HUSQVARNA Automower 430XH	8.5 inch
HUSQVARNA Automower 435X AWD	8.7 inch
HUSQVARNA Automower 450X	8.5 inch
HUSQVARNA Automower 450XH	8.5 inch
HUSQVARNA Automower 535 AWD	8.7 inch
HUSQVARNA Automower 550	8.5 inch
HUSQVARNA Automower 550H	9.9 inch
MCCULLOCH ROB R1000	7.5 inch
MCCULLOCH ROB S400	6.6 inch
MCCULLOCH ROB S600	6.6 inch
REDBACK POWER RM18	8.2 inch
REDBACK POWER RM24	8.5 inch
ROBOMOW RC306	5.8 inch
ROBOMOW RS612	4.2 inch
ROBOMOW RS622	4.2 inch
ROBOMOW RS630	4.2 inch
ROBOMOW RX20	6.9 inch
WORX Landroid L 20V WR150	6.6 inch
WORX Landroid L 20V WR153	6.6 inch
WORX Landroid M 20V WR140	6.2 inch
WORX Landroid M 20V WR143	6.2 inch

By the way, here you can find a current overview of all current robotic mowers with Edge Mode, which I would recommend.

But what exactly is this edge mowing function?

In normal operation, most robotic mowers drive criss-cross through your yard. The relatively chaotic pattern they follow is based on a system – which is not really recognizable for us humans – which in turn is calculated by a special algorithm. However, the algorithm does not account for mowing the very edges of the lawn.

There is always a little bit of lawn left at the edge because the blades of the robotic mower simply cannot reach the very edge. Often the mower will drive in random mode, sloping, or head-on towards the boundary wire, where it will turn around. Even if it is able to drive over the boundary wire a little bit, it will not reach all of the grass on the other side of the boundary wire.

Some manufacturers have come up with a solution for this, namely a function that we generally refer to here as “edge mowing function”. This is a function with which the robotic mower drives once completely around the boundary wire several times a week according to a certain plan, to mow the edge.

For example, your robot might do this every second day of the week before it starts the actual mowing for the day. It will try to get as close to the edge as possible and get as much of the lawn as possible.

The robotic mowers from WORX, the so-called Landroids, even have another special feature. While with all other robotic mowers the mowing unit is placed in the middle of the body- partly in order to maintain a certain safety distance between the edge of the car body and the blades- the mowing unit on the Landroid is mounted on one side and has only ¾ inch gap between itself and the exterior body. On this side a kind of grate prevents a foot that gets underneath from being injured by the blades.

This brings the Landroids even closer to the edge than all other robotic mowers. However…

There is no robotic mower that mows right up to the edge of a solid obstacle, such as a wall or fence. This is because, like a normal lawnmower, there is a certain distance between the blades and the body of the mower.

In order to be able to mow to the very edge, you can lay lawn edging stones in your garden.

Why Can’t Robotic Mowers Mow All the Way to the Edge?

One reason why robotic mowers are not able to mow the edge so well, I have already described above, and it relates to the mowing pattern of the robotic mowers. Because of the accidental criss-crossing they do not reach the edge so well, because they always arrive at an unfavorable angle.

But the far bigger problem is the distance between the blades and the body. The blades simply do not reach right up to the edge of the robotic mower, as is the case with lawnmowers. But not only that. Many robotic mowers have a so-called safety distance, which is a particularly large distance between the mowing unit and the outer body in order to avoid possible injuries that could occur if the robotic mower runs over someone’s feet, for example.

The independent and automatic operation of the robotic mowers makes this particularly large safety distance necessary. However, not all robotic mowers have this large distance.

Robotic mowers with blade discs, such as the models from HUSQVARNA,  MCCULLOCH or WORX usually adhere pretty strictly to this large safety distance, while other manufacturers such as ROBOMOW, AMBROGIO or WIPER with robust cross blades usually choose a smaller distance here.

This smaller distance together with the edge mowing function ensures that ROBOMOW mowers get relatively close to the edge.

WORX takes a unique approach with its models. They heed the safety distance, but have the mower on one side very close to the edge. Here, a grill is fitted in order to cover the blades and prevent any part of the body or any object that gets under the robotic mower on this side from being harmed.

With Lawn Edging Stones, Every Robotic Mower Can Mow Up to the Edge

As already mentioned, all robotic mowers leave a certain margin at the edges, even those with an edge mowing function. The latter only leave this margin where the lawn is bordered by a solid obstacle, such as a wall, because even there they cannot reach the edge completely due to their outer body. If they could drive a little over the edge, it is in theory possible that they can actually mow all the way to the edge with the edge mowing function. Yet, a strip of about 2 ½ inches would remain on the wall of the house, for example.

However, this does not have to be the case. No matter which robotic mower you choose, you can achieve a lawn mowed right up to the edge with any robotic mower.. This is possible with lawn edging stones.

These are flat stones that you sink into the ground at ground level with the lawn at the outer edge of the lawn. Here, the robotic mower can drive its wheels slightly over the edge of the lawn, which means that its mowing unit can reach right up to the edge of the lawn.

Depending on the robotic mower, the size of lawn edging stones needed may differ here. With a robotic mower that has edge mowing function, for example, you can choose quite narrow lawn edging stones. If you would like to know more about how wide the lawn edging stones should be and how this differs between the different robotic mower models, I recommend this article.

It is not a bad idea to use slightly wider lawn edging stones anyway, even if you have a robotic mower that can cope with quite narrow edging stones. This way you can keep your mind open to change to another robotic mower in the future, which may not have an edge mowing function.

Are There Alternatives to Lawn Edging Stones?

If you do not like lawn edging stones, there are alternatives. For example, you can also choose a strip of bark mulch as the outer border. However, this solution also has certain disadvantages. Robotic mowers with 3 wheels easily get stuck here when they drive over the edge, so you should only choose this solution if you have a 4-wheeled robotic mower.

Furthermore, bark mulch weathers after some time and must be replaced. In addition, it also removes nitrogen from the soil during its decomposition, so you will need to fertilize more often.

Lava grit is also used by some as a substitute for lawn edge stones. The same problem applies to three-wheeled robotic mowers. Otherwise you should know that lava grit increases the soil acidity significantly.

You can find out more about the different possibilities for lawn edging here.

Related Questions

How wide should lawn edging stones be? Lawn edging stones should be between 4 and 10 inches wide wide. The exact optimum width depends on the model of the robotic mower and the properties of the outer edge of the lawn. If there is room for the robotic mower to drive over the lawn edging stones with its body slightly, they can be narrower. If, on the other hand, they border a wall, they must be a little wider. The width can also be varied by placing lawn edging stones next to each other.

How well do robotic mowers cope with narrow passages? Depending on the model of robotic mower, the distance between the boundary wire and the robot must be at least between 24 inches and 40 inches in narrow passages. In longer narrow passages, the robotic mower needs an additional supporting function to be able to navigate through them, such as remote starting points. Many robotic mowers have difficulty mowing long narrow passages. This is where intelligent systems such as the Artificial Intelligence Algorithm (AIA) from WORX help.