October 10, 2024, 10:44 am | Read time: 5 minutes
Lawn thatch can become a typical problem in your garden. An expert at myHOMEBOOK explains how thatch develops, when countermeasures should be taken, and what measures you can take.
Over time, thatch can accumulate in the garden, frustrating many garden owners who strive for a well-maintained green space. This occurs because lawn grasses develop dense foliage with side shoots, runners, and roots, which eventually become thatch. myHOMEBOOK asked Dr. Harald Nonn from the German Lawn Society how to effectively combat this.
Does thatch disappear on its own?
“Some of this plant matter dies off during the growing season,” explains Nonn. Normally, microorganisms would break down this material. “However, if the mass of organic matter is too large or the microorganisms are missing, the dead plant material accumulates on the soil surface as lawn thatch,” says the lawn professional.
According to Nonn, lawn thatch contains a lot of lignin, which microorganisms find difficult to digest and slow to break down. Garden owners should, therefore, take mechanical measures, such as scarifying, to counteract the accumulation of thatch.
How much thatch is still acceptable?
Nonn explains that a thin thatch layer, up to a maximum of one centimeter thick, is perfectly acceptable in a lawn. The layer also offers benefits. “It protects the growing point of the grass when it’s walked on or driven over, and it reduces water evaporation from the soil.” At the same time, however, it also stores water, which must be taken into account when watering the lawn. This means that more water is needed so that it reaches the grass roots in sufficient quantities.
Scarifying to combat thatch
The lawn professional recommends scarifying the lawn to remove thatch. The best time for this is spring, after the grass has started to grow. If there is little or no thatch, scarifying is not absolutely necessary, says Nonn. This is especially true in the fall. “If scarifying is carried out after all, the damage must be allowed to grow out before the end of the growing season so that the gaps are closed,” explains the expert. “Otherwise, the invasion of foreign species is encouraged.”
When it’s better not to scarify
When scarifying, the blades or spring tines of the device should cut through the felt pad and only lightly touch the ground. Then a good result can be expected. Scarifying too deeply can cause significant damage to the grass. It can also create gaps in which weeds can quickly spread. “The lawn aspect also suffers,” adds Nonn.
During hot weather, the lawn can quickly suffer from drought damage, as scarifying also puts the lawn grasses under stress and sometimes injures them. The evaporation rate also increases. However, the scarifier should also be left in the tool shed when it is very wet. Otherwise, the working tools would “smear” and lead to an inadequate result.
Does organic fertilizer save scarifying?
For myHOMEBOOK, Nonn puts the theory “If the lawn is fertilized organically twice a year, scarifying is not necessary” to the test. After all, fertilizing is less work – and not every garden owner has a scarifier at home.
So does regular fertilization of the lawn save scarifying? Nonn explains: “Organic material is broken down and mineralized by microorganisms in the soil.” This biological activity differs from site to site and depends on many factors. “More decisive than the form of fertilizer – organic or mineral – is sufficient gas exchange in the soil,” says Nonn. This refers to the aeration of the lawn, also known as “aerification.”
The soil organisms essential for thatch decomposition are only active with an adequate oxygen supply. These organisms then utilize the available organic sources for energy production and biomass synthesis, typically present in ample amounts in the lawn.
Frequently Asked Should you scarify lawn in the fall? A professional explains
Lawn calendar How to care for your lawn in December
Lawn calendar What the lawn needs in September
Is a rake with pointed tines enough?
“You certainly don’t necessarily need to buy a motorized scarifier for a small lawn,” says the lawn professional. In contrast to lawnmowers, scarifiers are used much less frequently. “However, anyone who has manually scarified 100 square meters of lawn with a rake understands the significant effort required.” A scarifying rake is a good option for small areas and for working out a flat felt layer at an early stage, says Nonn. By the way, scarifiers can also be hired from many garden centers or DIY stores.