Check for thatch by using a knife or soil probe to remove a core. The dense organic layer above the soil line is thatch. Mechanical Dethatching To combat thatch, use a dethatching implement or vertical mower that cuts through the thatch to the soil surface. As it passes through the grass, dead and living organic material is cut, torn loose, and deposited on the surface. Operation of dethatching machines is relatively easy, since they are partially self-propelled.
Most difficulty occurs on steep slopes or when soil is very dry.
Select a dethatching machine that cuts with knives or blades. Some machines have flexible, leaf rake-type tines that are ineffective in removing thatch. Spring tines that can be attached to your rotary mower blade are not good for dethatching either, and can cause severe mower damage. Dethatching equipment can often be rented from lawn equipment rental companies. The organic material dislodged by the dethatching machine should be removed and composted or discarded.