Can the robotic lawnmower cut tall grass?

Robotic mowers have become extremely popular in this country. The devices improve lawn quality noticeably through regular cutting and simultaneous mulching and ensure a perfect and even cut without any intervention. Consequently, they are often used for lawns with a comparatively low cutting height.

Reasons for high grass in the garden

The robotic mower does not always encounter a short-trimmed, well-manicured lawn. There are moments when the grass has simply grown taller:

• after longer breaks in the rain
• after the robotic lawnmower has taken a break for some time during a vacation
• at the beginning of the lawn season before the first cut.

However, special types of lawns, such as shade lawns, also require a greater cutting height than commercial or ornamental lawns. Moreover, you may choose not to cut too deeply in favor of biodiversity. In meadows, grass often grows 4 to 6 centimeters longer than a commercial lawn would. This, in turn, poses problems for many models.

The cutting height of a robotic lawnmower

Manufacturers specify the respective cutting height for their models. In most cases, this is between 15 and 60 millimeters. While this is ideal for commercial and ornamental lawns, it is not ideal for shade lawns. Luckily, there are also robotic mowers that are specially designed for taller grass with a cutting height of up to 100 millimeters.

The cutting height can be adjusted either via a lever or display, depending on requirements. 

Other equipment features for mowing tall grass

Often, tall grass is accompanied by a surface that does not create optimal mowing conditions for robotic mowers. Bumpy surfaces or depressions in the ground can cause the robot to drive over some areas causing the cutting length to be uneven. Here, additional equipment features help to counter this problem, so that they can cope accurately with any type of difficult terrain.

• A pendulum-mounted mowing deck follows the contour of the ground providing a uniform cutting length.
• All-terrain wheels with a coarse tread pattern perform well on slopes and in wet grass. They also reduce the risk of getting stuck on uneven terrain and ensure that your robotic lawnmower moves safely at all times.
• A powerful battery is especially important on large lawns so that the robotic lawnmower can do its job efficiently. Long mowing times mean that the device has to go to the charging station less often and thus spends more time on the lawn.
• When mowing orchards, fallen fruit or leaves are often left on the ground and make the work of some robotic lawnmowers visibly more difficult (especially in autumn). Although it is advisable to remove fruit as well as leaves regularly, some robots can cope better with these obstacles. Robots with star blades have a clear advantage over those with knife blades. Star blades are much more robust and easily shred fruit and leaves while knife blades are more prone to jamming.

Cutting length and mulching

Robotic mowers with a cutting length of up to 10 centimeters also handle tall grass excellently. However, the same mowing conditions apply here as with short grass.
Due to the mulching function – a robotic lawnmower cuts off the stalk tips, which then remain on the lawn to decompose. The robotic lawnmower adds valuable nutrients to the soil with every cut and noticeably reduces the intervals between fertilizing. At the same time, the mulch layer keeps the soil moist longer. 

Be that as it may, mulching only works if the stalk tips are very short. Longer grass clippings can take a long time to decompose. If this happens, the lawn will not sufficiently aerate and, in the worst case, begin to rot.

It is recommended that the cutting interval be around every 2-3 days, even with tall grass, so that you can do without collecting the grass clippings manually afterwards.

If this is not possible, such as the first cut after the winter break, it is better to use another type of lawn mower, especially if you do not want to go through the trouble of raking up the grass clippings.

If you want your lawn to have a cutting length that exceeds the cutting heights of most models, it is worth purchasing a robotic lawn mower that can easily handle up to 100 mm of cutting height. In addition, other features may be beneficial to produce a perfect cut.