Lawn mowing:

The optimum cutting height when mowing your lawn

While in other countries cylinder mowers are very popular, in German gardens it is primarily sickle mowers that are used as petrol, electric or battery-powered lawn mowers. These lawn mowers cut the grass with horizontally rotating blades. To ensure that this cut is clean and the grass blade does not fray, the blades of the sickle mower must be very sharp. Therefore, you should therefore sharpen the blades of your lawn mower at least once a year – either in your local workshop or with the help of a specialist dealer. Simply pick a few of the blades to check. If you see fringes and uneven cuts, the blade is blunt. Also make sure that the motor speed is high when mowing. The higher the motor speed, the faster the blades rotate and the faster they rotate, the cleaner the cut.

The cutting height on the mower can usually be adjusted in several steps. These steps do not usually translate 1:1 into centimetres, so step 1 is not necessarily 1 cm in cutting height. You can look up which step relates to which cutting height in the operating manual of your lawn mower. If you don't have it to hand, you can mow a small area – preferably in the shade – and then measure it.

For a normally used lawn, a cutting height of 4 cm is ideal. Shady areas should be mowed one to two centimetres higher. In this way, the grass will have more green stalk area for photosynthesis and it can cope with the reduced sunlight. Purely ornamental lawns can also be cut shorter to about 3 cm.

Too short a cut will damage the lawn, especially in dry periods. If it hasn't rained for a longer period of time, you should also leave some slightly longer blades of grass. If the grass is too short, the roots also suffer, as they are no longer protected from direct sunlight. Too short stalks and unprotected roots quickly dry out the lawn and turn it brown. In addition, further growth is an immense effort for grass that has been mowed too short. Mosses and weeds like to take advantage of this opportunity to displace the weakened grass plant in the garden and spread themselves. However, if you let the stalks get too long, you take away the stimulus for further growth and weeds spread.

Always follow the 1/3 rule when adjusting the cutting height. This follows the natural growth of the blade of grass by taking its vegetation point into account and is usually about half the height of the blade. If you also cut it, it takes a relatively long time for the shoot to recover and start growing again. If this happens, your garden lawn will become patchy. Therefore, it is recommended to mow a lawn that has grown longer, for example because of a longer holiday, in several stages so as not to cut off too much at once and to slowly shift the vegetation point back down again.

The right time to mow your lawn

As already explained, the recurring cut ensures that the grasses branch at the base and form a nice dense surface. Therefore, under normal conditions, one week is considered the optimum mowing frequency – depending on the weather, fertilisation, irrigation and location in the garden.

Mowing your lawn in summer

In summer, regular mowing ensures optimum growth of the lawn. This also significantly slows weed growth. In the warm summer months you should cut your lawn at least once a week – but not too short! Five cm stalks protect it effectively from drying out. Never mow your lawn in the blazing midday sun, but opt for the cooler evening hours or first thing in the morning.

Mowing your lawn in autumn

So that your lawn can get going again with full power next spring, the right preparation for the winter is crucial. As long as the weather permits, you should mow the grass as usual. The time for the last mowing depends on the temperature. As long as it's not too cold at night, the grass will continue to grow. The first frost usually arrives in mid to late October. This is the right time to mow the grass one last time. Pay attention to the correct cutting height. Cut the blades half a centimetre more than usual. If the lawn is too long, the first snow could push the blades down and increase the risk of fungus and disease. To reduce this risk even more, you must always remove the grass cuttings from the last cut and not leave them as mulch.

Mowing your lawn in winter

In winter you can leave your lawn to rest. The grass only grows a little or not at all during this time. However, make sure to remove leaves regularly so that the lawn gets enough light and the soil does not get too wet. The latter is especially important during prolonged frost, as frozen blades of grass can break off as soon as they enter the lawn and the lawn can only recover from this with difficulty in spring.

Mowing your lawn when wet

The lawn should not be mowed when wet, as damp leaves and stalks are often not cut cleanly. This puts more strain on the grass than necessary and the cutting pattern suffers because the cuttings clump together and cannot be blown completely into the catcher. On wet ground, the wheels can sink in and cause damage to the grass roots – the heavier the machine, the greater this risk.

Mowing the lawn in the heat

If temperatures rise above 30 °C, mowing the lawn is also not advisable, as the soil would dry out too quickly. In the morning, the grass is usually still too wet, so late afternoon is perfect for mowing. Afterwards, you can easily water the freshly cut lawn.

Using mulch as fertiliser

Our final tips: If you mow your lawn frequently and only cut the blades by a few millimetres, you can also leave the grass tips on the lawn as mulch. This thin layer of grass cuttings then acts as fertiliser, stores some water and promotes humus formation and the crumb structure of the soil. However, this only works if the grass falls as very short snippets. If this is not possible, it is essential that you collect the grass clippings, otherwise they will deprive the plants of the proverbial air to breathe.