The one-third rule suggests that you should remove no more than about one-third of the grass height in a single mowing. Mowing too abruptly or too short weakens the lawn, especially during periods of drought or heat.
The one-third rule is easy to apply with numbers
The essence of the rule is to remove no more than one-third of the current grass blade height in a single mowing. If you want to maintain a height of 4 cm, it is worth mowing before the grass significantly exceeds 6 cm. This is a simple example and not the only suitable lawn height: the specific value depends on the grass mixture and conditions. It is important to preserve enough of the green part of the leaf. The desire to tidy up overgrown grass in one go can cause additional stress and worsen its appearance, even if the surface looks neat on the first day.
Mowing frequency should follow growth. When the grass is actively growing, one mowing per week may not be enough to maintain the chosen height. When growth slows down, there is no need to mow just for the sake of the calendar. A robot is useful in that the work can be spread out into shorter, regular sessions. However, even with a robot, overgrown grass must be shortened gradually. During periods of heat and drought, check whether the selected height is too low and follow the maintenance recommendations for your specific mixture.
How to apply this in practice?
If the grass is overgrown, reduce the height in several stages. Adapt the mowing frequency to growth: during active periods, you may need to mow more often, while during periods of slow growth, you can space out the schedule.
- Choose a target height suitable for your grass mixture and the season.
- Measure growth in several places, not just by the path.
- Reduce overgrown grass over several mowings, without making a sudden change.
- Adjust the robot's schedule according to growth and soil moisture.
A practical example
Let's say you want a 5 cm lawn, but you find 10 cm grass when you return from vacation. Mowing to the final height in one go would mean removing half of the blade. It is wiser to start higher and then, while monitoring recovery and growth, gradually switch to the desired setting.
Can you keep the same schedule for the entire season?
Only if it remains suitable for actual growth. Conditions differ in the spring, during heatwaves, and in the autumn. Review the height and frequency when grass growth changes or if you notice signs of lawn stress.
What is worth remembering?
A robotic lawnmower can help maintain a constant height with small, regular cuts. Still, monitor the condition of the lawn and choose a height suitable for the grass species and the season.
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