Quand et comment aérer la pelouse ?

Aerate the lawn? Why?

Grass, like everything else that grows, needs oxygen. There are bacteria and fungi in the soil that break down dead plant parts and convert them into nourishment for the grass, and this requires oxygen. Without oxygen, other types of bacteria and fungi start a decay process that also breaks down the dead plant parts. However, this process risks forming a so-called "black layer" – a layer of black soil that contains sulfur gases that smell bad and create very poor conditions for grass to grow.

Compaction cause lack of oxygen

But why is there a lack of oxygen in a lawn? One reason is that the soil is compressed by external pressure over time, a process called compaction. It happens to lawns in all gardens where people walk, work and play lawn sports. In compacted soil, the grass roots receive less oxygen, and the drainage worsens, leading to less water and nutrients penetrating down to the roots.

How compact your lawn becomes can also depend on the type of soil. Heavy and muddy soil sinks and becomes hard and condensed, leading to worse grass conditions. By aerating the lawn, you make it easier for the grass to breathe and better absorb both nutrients and water. It also becomes more resistant to weeds and pests.

Best way to aerate lawn

There are different ways to aerate a lawn. One way is to stick solid sticks into the ground, creating holes where air, water and fertiliser can penetrate. You can also use hollow sticks or hollow pipes, with which you pull up soil, a bit like when you core an apple. There are several varieties of tools, and also special spikes that make little holes when you walk them over the grass. If you have a robotic lawn mower with boundary wire, be careful not to damage the wire.

Aerate your lawn using scarifier

Another way is to use a scarifier. It is a tool with rotating blades that go down a couple of centimeters into the soil, ripping up old grass clippings, moss, and other debris. When you run it over the lawn, the roots are cut so the grass plants are split up. It stimulates the growth of lateral shoots, making the lawn denser and greener.

Best time to aerate lawn

It is best to aerate the lawn during the period when the grass is growing at its best, i.e. during late spring or early summer. When the grass has been cut a few times and feels firm, take the opportunity to walk on it before it gets too hot and dry. If the soil in your garden is very compact, you may want to aerate your lawn once extra per season, preferably in early autumn. Avoid aerating it during the height of summer when it is hot, and the lawn can be very dry. If you aerate in the summer, make sure to water a little more often in the next few weeks.