Lawn care – Why It Is So Important To Remove Thatch And How To Do So

Feb 19
17:16

2008

Jonathan Ya'akobi

Jonathan Ya'akobi

  • Share this article on Facebook
  • Share this article on Twitter
  • Share this article on Linkedin

While watering, feeding and correct mowing are pre-conditions for growing a successful lawn in a hot climate, the periodic removal of thatch could make the difference between a great lawn and a cabbage patch.

mediaimage

One of the conditions required to grow a beautiful lawn is the periodic removal of thatch. Thatch is the layer of the lawn’s roots and stems that builds up above the soil’s surface. A high percentage of organic matter in the soil is desirable when that organic matter has broken down to the black and crumbly state known as humus. However,Lawn care – Why It Is So Important To Remove Thatch And How To Do So Articles thatch is composed largely of matter that breaks down so slowly that if left untreated just grows and grows.

Problems associated with thatch

*A thatch layer forms a fairly impenetrable mass severely retarding both the infiltration of water into the soil, and the all important exchange of gasses from it. A poor rate of gas exchange means that carbon dioxide builds up while insufficient oxygen is available to the grass roots.

*The higher the layer, the more difficult it becomes to mow the lawn correctly. As the layer grows, the lawn mower sinks into the grass causing it to scalp instead of mow the lawn. In some species, especially those particularly sensitive to scalping, this can be fatal, while even amongst those species which can take some punishment, periodic scalping will cause the lawn to degenerate.

*Thatch is an excellent breeding ground for pests and diseases, a problem further exacerbated by the need to water very frequently, caused by the poor infiltration of water into the soil. Many plant pathogens thrive of course in moist and humid conditions.

Dethatching the lawn

Not all grass species produce thatch to the point where it becomes problematical. It is most common amongst the perennial grasses grown in hot summer and mild winter climates such as the Mediterranean countries, south west Australia, or California. When the grass starts to feel spongy, it is clear that a layer is forming. It can be removed in both the spring and late summer by use of a dethatching or scarifying machine. The tool works like a vertical lawn mower, lifting up the dry organic matter as it progresses. The thatch should be raked into piles and removed to the compost heap.

It is very important to be aware that some species can be damaged terminally by dethatching that is performed too aggressively. As a rule of thumb, the perennial species that spread by way of stolons (stems that grow horizontally above the ground) are most sensitive, as they are to scalping, while those species that spread by virtue of rhizomes (stems that also grow horizontally, but below the ground) actually benefit from a severe dethatching in the spring.

Lawn care techniques that reduce the build up of thatch

*Infrequent watering, with proportionally larger quantities at each session, slows down the thatch build up by encouraging deeper rooting. Conversely, frequent watering causes shallow rooting and even the development of roots that grow above the ground, in the thatch layer.

*The level of lawn fertilizers in the soil, affects the amount of thatch and the rate at which it is produced. On the one hand, excessive nitrogen causes the rate of production to rise, while too little retards the break-down of the organic matter, as the organisms that break down the roots and stems, require themselves a supply of nitrogen. For this reason at least, spreading readily dissolvable fertilizer, especially in the summer, is undesirable, while the application of slow release fertilizer is to be preferred.

*Adding compost to the soil is almost always a necessary act. However, in cases where a heavy thatch layer has built up, compost can actually worsen the problem. A non-bulky organic fertilizer is to be preferred in these circumstances.