Robot mower and hedgehogs: safe settings

A convenience with caveats

A robot mower is a blessing for many gardeners: doing the mowing yourself becomes history. But this handy machine has a dark side. Hedgehogs, amphibians and small mammals face serious injury or death if you do not operate the mower carefully. This article helps you set up your mower safely so you enjoy the benefits and animals do not suffer.

The key is a golden trifecta: mow only during daylight, set the correct cutting height, and handle edges properly. Modern robot mowers increasingly have built-in sensors that detect dangers, but the old rules remain worth their weight in gold. Read below how to combine both.

Why night mowing is dangerous for hedgehogs

Hedgehogs are nocturnal. After sunset they leave their shelters and search for insects, slugs and worms. This usually happens between 7 p.m. and 6 a.m. Robot mowers active at night encounter hedgehogs with one consequence: cutting or crushing injuries, often fatal.

A hedgehog cannot flee fast enough. Its natural defence, rolling into a ball, does not help against rotating mower blades spinning thousands of times per minute. Moreover, robot mowers do not see the animal because they have no eyes but use laser sensors or gradients. Hedgehogs across Belgium and the Netherlands are injured by robot mowers every year.

This is not an exaggeration. Hedgehog charities and wildlife rescue centres warn every year about this danger. You have it in your hands by setting your mower to operate only during daylight.

Daylight only: the crucial setting

This is rule number one. Set your robot mower so it is active only between 6 a.m. and 8 p.m. In your mower you will find a scheduler section (in some brands called "Timer" or "Schedule") where you can lock this in.

The ideal setting: Start at 7 a.m., stop at 7 p.m. This gives hedgehogs the entire night undisturbed. If you are in summer (with long days), you can go until 8 p.m., but mowing must stop at the latest. Many modern mowers even have sensors that automatically stop if movement is detected, but do not rely completely on this technology. Manual settings are more reliable.

Check your mower at least once per week: is it working to your schedule? Sometimes batteries revert to factory settings, or the timer gets reset by weather.

The correct cutting height: not too low, not too high

Many people set their robot mower too low, hoping to need fewer mowing runs. This is a classic mistake. Low cutting heights (under 4 centimetres) increase the chance that small animals are injured and weaken your lawn.

The golden rule: Set your mower to a minimum cutting height of 5 to 6 centimetres, depending on season.

In spring (April-May), as grass grows quickly: 6 centimetres. In summer (June-August): 5 to 6 centimetres. In autumn (September-October), as growth slows: 5 centimetres. In winter (December-January) many gardeners do not mow at all; if your grass still grows, turn mowing off.

This height does not completely exclude small animals, but it greatly minimises injury. Moreover, your lawn benefits. Longer grass means deeper roots, better water retention, and less competition from weeds.

Note: some robot mowers have a minimum height of 2 centimetres. Do not go below the limit. Many of these machines can be adjusted with extra wheels or adapters, which raises cutting height. Check your manual.

Edges and hard-to-reach places

Robot mowers do not mow everything. They do not optimally reach edges, corners and narrow passages. This is actually an advantage for small animals: damaged edges can be important "escape routes" for hedgehogs to hide in.

However, make sure you trim edges regularly by hand (with an edge trimmer or small handsaw) so that dense thickets and grass do not grow unchecked. Hedgehogs love sheltering in long grass and dense shrubby areas, so encourage this by letting edges grow a bit wild.

Narrow path between your garden and your neighbour's? A robot mower will not fit. Perfect: these places can be important trails for hedgehogs. Leave them free. If you want to mow them, do it by hand at quiet times (for example, on a Friday afternoon).

Make sure your robot mower cannot get stuck or lost in a narrow passage. Many mowers need boundary wire (a kind of underground fence) to know where to go. Set this wire so that no dead ends are created.

Models with sensors: a step forward

In recent years robot mower manufacturers are increasingly adding sensors to their machines. This is good news for animal welfare, but not a miracle cure.

What these sensors can do:

• Detect obstacles (branches, stones, footballs) so the mower does not get stuck.
• Detect rain so the device returns to the charging station.
• In luxury models: infrared or radar to recognise animals.

What they CANNOT do:

• Prevent a hedgehog from bumping into the mower, especially if both encounter each other at full speed.
• Distinguish between harmless, fast movement and an animal.

The truth: even the most expensive robot mowers with sensors cannot guarantee safety. It remains crucial to keep the mower active during daylight.

If you choose a model with sensors, check that they actually work in your garden. Sometimes sensors do not work well in damp gardens or if much grass accumulates on them.

Lawn in moderation: not everything needs to be bare

Many robot mowers are programmed to mow at least twice a week. But did you know? Your lawn can easily manage less frequent mowing, especially in autumn.

Instead of twice weekly, try once a week. This saves battery time, reduces the mower's footprint, and gives animals more time to cross the territory safely without encountering a mower.

Let your grass grow a bit wilder in autumn (8 to 10 centimetres before mowing instead of 5). This helps hedgehogs because they use longer grass to forage and dig shelter in. In autumn hedgehogs need extra food to prepare properly for hibernation.

All this not only helps small animals but makes your garden greener too. A slightly wilder lawn attracts more insects, which attracts birds, and future bees and butterflies. Mowing less often is therefore simultaneously better for animals and the environment.

Not sure how a slightly wilder lawn edge would look in your own garden? On gardenworld.app you see it first in a sample of your own garden, before you change anything.

Placement: where you position your robot mower

Where you place your charging station affects the behaviour of hedgehogs and other animals. Place the station somewhere that does not sit directly in a frequently used animal trail. Ideal is a corner close to your house, where people pass regularly (animals avoid that).

Make sure your robot mower does not travel between its station and the lawn at night. This is especially relevant for mowers that independently find their charging station. Many new models can only go outside during the day, which is good.

Check your boundary wire regularly for damage. If the wire is broken, your robot mower can grow outside its zone and end up somewhere unexpected.

Step by step

A robot mower can be safely used for years if you follow these points. The benefits are real: less work, a better-maintained lawn, and more time for what you enjoy. But this should not come at the cost of the health of hedgehogs and other small animals.

Step 1: Daytime set

Open your mower, go to the timer or schedule and set: mow between 7 a.m. and 7 p.m., all seven days. No night exceptions. Check this every week.

Step 2: Check cutting height

Set your mower to at least 5 centimetres. Is your grass very sensitive or do you have lots of wet weather? Set it to 6 centimetres. Your lawn will thank you. Check monthly that wheels do not wear (then cutting height drops).

Step 3: Handle edges

Plan 15 minutes every two weeks for manual edge trimming. An edge trimmer is sufficient. This keeps your garden neat and gives animals enough shelter.

Step 4: Maintain sensors

Does your mower have sensors? Check monthly that they are still clean (no grass, dirt or mud). Clean with a dry cloth. Test the mower regularly on open ground.

Step 5: Boundary wire

Check the wire monthly for breaks. A broken wire is a major risk. Repair immediately.

Step 6: Lawn care

Give your lawn extra care in April and September: fertilise, aerate, possibly reseed bare patches. A healthy lawn does not grow so wildly and your robot mower does not have to work so hard.

Frequently asked questions

My robot mower has no timer. Can I still use it safely?

Difficult. Machines without planning features will work much more randomly. Many of these older models cannot be upgraded. Consider upgrading to a newer model with smart settings. The investment pays for animal safety.

I live in a residential area with many hedgehogs. Must I turn off my robot mower completely?

No, but be extra careful. Set it to operate from 8 a.m. to 5 p.m. (shorter than normal). Check every day that it is still on. Consider a model with animal sensors. And: help manually by trimming edges yourself in the evening.

What do I do if I find an injured hedgehog in my garden?

Touch the animal gently and place it in a cardboard box with some damp grass. Call an animal ambulance or hedgehog rescue immediately. Turn off your robot mower until the animal is past. This can be vital.

Can I mow at night if I have closed-off hedges?

No. Even with an enclosed garden hedgehogs can get inside (many garden fences have holes). And: amphibians and slugs are also nocturnal and deserve protection.

See it in your own garden first

Want to see how your lawn looks with a wildlife-friendly mowing rhythm? Upload a photo of your garden to gardenworld.app and view for free a sample of a new design with this lawn. The sharp image with plant list costs 7.99, one-time, no subscription.