Over time, little bits and pieces of grass die and gather just above the soil. This is called thatch. A little bit of thatch can be beneficial. It’s organic material that is broken down by microbes in the soil. But sometimes, thatch builds up too fast for natural processes to break it down. It forms a barrier, keeping moisture and air from going where your grass needs it. A half-inch or more of thatch can weaken your lawn. You have 2 ways to remove it: dethatching and aerating.
If your lawn doesn’t seem to be growing as well as it should, even though it’s being fed regularly, it may be because of either thick thatch or compacted soil (or both). In both cases, the grass is suffering because air, water, and nutrients aren’t able to move freely into and through the soil, and are having trouble reaching the roots. You can tell your soil is overly compacted if you can’t easily insert a screwdriver into it. When thatch (bits of grass that have died and gathered just above the soil line) is too thick, your lawn will feel spongy, and it will be difficult to stick your finger through to the soil.
Dethatching is also a great way to remove moss in a lawn. The blades of the machine easily pull the loose moss out as it is run over the lawn, this can result in bare or thinned areas which will require overseeding after.
What is Dethatching?
Thatch is a layer of living and dead grass shoots, stems, and roots that forms between the green grass blades and the soil surface. Some thatch (1/2 inch or less) is actually beneficial; it acts like mulch to provide insulation from temperature extremes, helps keep moisture in the soil, and provides a protective layer of cushioning. However, when the thatch layer is more than ¾ inch thick, it can lead to increased pest and diseases problems (and reduce the effectiveness of some fungicides and insecticides), and reduce the amount of oxygen and moisture that are able to reach the soil and grass roots. When this happens, it’s time to dethatch your lawn. Dethatching removes this thick layer of decaying plant material so air, water, nutrients, and fertilizer can reach the soil better, plus your lawn can drain more effectively.
*Courtesy of Scotts