Lawn Maintenance

This entry was posted by on Monday, 29 August, 2011 at

Some of us are lucky enough to have a garden, possibly with a lawn. As this is (or was, I don’t have a lawn where I live now) one of my hobbies, I’ll share some knowledge on this topic.
Rule of thumb: cut about one third of the total length at once. Mow about once per week, more often during exceptionally grow-some weather (warm and humid). If you opt for a lawn to be used as a playground, the grass should be just above the flat hand, say 3.5 to 4cm. For a nice lawn with golf-court green effect, mow at about 2.5cm. During drought, it is better not to mow or raise the height at which the mower trims (the grass will loose a lot of moisture through the cuts and may turn yellow).

Mowing a new lawn: cut at a height of about 8cm the first time, after you have rolled the lawn the day before (to compact the soil).

Which lawnmower?

  • Circlemower – either electrical or with a combustion engine. This type of mower chops the grass. It creates some sort of suction which pulls the grass upright. There are also so-called mulch-mowers which chop up the grass into very fine pieces. Dull blades cause a rough cut, so you should sharpen the blades every year.
  • Cagemower – knives in a cage literally cut the grass. They give a very nice and clean cut, but do not provide a mulch function (unless, of course, you cut only a very small part).

If the clippings are not too long (or if it is not too much), it is best to leave it on the lawn. The sun will cause it to shrink, and it will disappear between the grass when it rains. This provides fertilisation to the ground. If you decide to use a mower with a grass retention box/bag or rake the clippings, keep in mind this needs to be compensated with fertiliser.


  • Older lawns – broad-leave weed should be removed as much as possible by hand. On large areas you can spray MCPA (2-methyl-4-chlorophenoxyacetic acid, a herbicide). Make sure the grass has not been cut for a few days before applying this, do not apply during bright sunlight if possible.
  • Younger lanws – after mowing a few times, about 90% of all weeds will disappear – they simply die because they don’t do so well when they’re only 3cm tall! Be careful with herbicides, read the instructions and mind the weather. Young grass is quite vulnerable. Before you either sow or lay down the grass it is best to first remove any remaining weeds by using Roundup or similar.

Apply chemical herbicides only when the grass is strong and showing good growth.

If your lawn is plagued by moss, first find the possible cause:

  • Mowing too short – the grass cannot recuperate fast enough and the moss will dominate
  • The moss grows faster if the grass does not get enough fertiliser
  • The lawn is in the shade; it will remain wet for too long
  • Acidic soil

Grass hardly grows when the temperature is below 15 degrees Celcius; moss can grow when temperatures drop to about 5 degrees. That’s why you’ll notice moss shortly after or during winter. Shade is a difficult problem; as it is not always possible or desirable to remove trees etc. Promptly remove any fallen leafs.

Several substances are available to combat moss, predominantly with ferrous sulphates. You can also get moss-terminators with fertiliser, a 2-in-1 approach.

Two things are important when eradicating moss:

  1. Removing moss may cause large empty spots – repair promptly with grass seed or the moss (or other weeds) will claim the ground.
  2. Once you have identified the cause of the moss, try to do something about this.

Aerating grass is a great way to get rid of moss – it is like combing the moss out of the grass. Afterwards, make sure you repair empty spots.

Compacted soil
“Fatty” ground needs to be loosed with some coarse sand, as it does not air as well and may inhibit water to pass through, causing pools of water on the lawn, which in turn may cause moss. Using a pitchfork you can allow more air to get into the soil.

Chalk, or a type of limestone known as calcium carbonate CaCO3, can be used to mitigate acidic soil. It is best to apply this before winter.

When the grass clippings do not degrade fast enough a spongy, soft mat can accumulate over time. This is also one of the causes of moss-growth. Ensure that the amount of grass clippings is never too large. A thick layer of filt can be removed with a rake.

The Rake
In spring/summer, when the grass is in full growth, it is often beneficial to rake the grass every now and then to remove old grass and erect flat grass. After mowing the lawn will usually quickly recuperate. This works great to prevent build-up of a filt-layer as discussed above.

Clover hates nitrogen (N), so use a fertiliser which contains nitrogen. Clover does not need to be a problem if you cut the grass on a regular basis. A benefit of clover is that it remains green until late in the season, and it carries flowers if left to grow.

Choose either organic or anorganic fertiliser.

  • Organic – activates little critters in the soil and hence improves the quality and structure of the soil. Examples are cow manure and compost and various commercially available fertilisers.

    • the grass does not suffer burns
    • it works for a long period. When the temperature rises, life in the soil will become more active.
    • There are no growth-peeks
    • Applying twice per year suffices
    • The quality of the soil improves
    • The lawn is less susceptible to drought
    • Does not wash out


    • May stink
    • May be expensive
  • Anorganic – artificial fertiliser, ready-to-eat food for plants. Usually NPK 12+10+18 with Nitrogen, Phosphate and Potassium (that’s the K for Kalium). There are many varieties available.

    • Nutrients are directly available to the plant
    • Easy to apply
    • Cheap (several special types excluded)
    • Does not stink


    • Must be applied once every 5 to 6 weeks
    • Easy to forget, especially if the weather is unsuitable
    • Washes out – and can accumulate elsewhere.
    • Causes peeks in growth
    • Great risk of burning the grass (always apply on dry grass, preferably just before a rain shower).
    • Does not improve the soil

    When to apply fertiliser? Spring is the best moment. Start around March, after that apply small amounts until September (depending on the type and instructions of the fertiliser). A poor lawn can be revived by applying compost.

    Do not sprinkle too much, this is an error many people make. Watering too often will cause the grass to become “lazy”: it does not grow its roots deep down into the soil because it is able to get its moisture at the surface. This makes the lawn very vulnerable to drought. It is better to thoroughly soak once per week than a little bit more often, but make sure you do not do this in the full sun: this may cause burns on the grass. Do not allow puddles to form: use a “slow” sprinkler which covers a large area.

    You can use special scissors, a weed-eater (a machine with a string which rotates at high speeds and cuts, well, weed), or a large knife. I found the knife to give a very clean cut, especially if it is thoroughly sharpened. Beware that cutting ‘into’ the ground causes it to become dull rather quickly so don’t use your best blade.

    Also, using a sharp shovel (or the same knife) to ‘cut the lawn in pieces’ can give an extra growth impulse to the grass, as the chopped roots tend to rapidly regrow into a more dense network of young roots. If the grass is not lazy, the roots can go as deep as 20 to 30cm, providing a very good base for lush green on top.

    Strong grass
    With proper care, grass can be both beautiful and a playground. Pay attention to fertilisation, watering, taking care of moss and the quality of the soil and you too can have a nice lawn, even when it is ravaged by kids every now and then.

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