Scarification

Thatch is a layer of dead grass cuttings, dried leaves and other organic debris that falls on the lawn. In most cases the bacteria in the soil will break this thatch down. In a number of lawns the bacteria cannot cope with the levels of debris and we get thatch building up. This acts as a barrier between the soil surface and the atmosphere.

Scarification is the process of removing thatch from the lawn. Although a certain amount of thatch is desirable in all lawns, an excessive level of thatch will cause severe problems. Thatch will form a barrier between the soil and air surface, blocking the flow of air moisture and even nutrients into the soil where it is required by the grass roots. In dry conditions the thatch will soak up any moisture that falls on the lawn and hold the moisture near the surface, where a large proportion of the moisture will evaporate due to the sun and wind and not get to the roots of the grass. Alternatively in heavy rainfall the thatch will hold water for long periods creating a damp environment that will encourage the growth of moss and disease.

Thatch can be removed by scarification which uses machines with vertical blades slicing through the thatch, scraping the soil surface and removing the thatch. Do not confuse scarification with lawn raking which in most cases has little effect on surface thatch but just removes some of the moss that is present in the lawn. Raking can spread moss spores across your lawn. Scarification removes the thatch thereby addressing the condition that encourages moss to develop.

Scarification can be quite hard on lawns. The process of scraping out the thatch does not make your lawn look good. Areas that are heavy with thatch and have a high % of moss present will look very bare after scarification and will probably require over seeding with some seed and top soil, and careful watering to recover.

It is highly recommended that scarification is carried out after an application of moss control and during a period when there is lots of natural moisture forecast to help the lawn recover.

Sub surface thatch is a level of thatch that has over the years developed just under the soil surface. Sub surface thatch reduces bacterial aerobic activity. Moisture is held on the surface encouraging the grass roots to stay close to the surface where the moisture is instead of developing long roots. Sub surface thatch requires aeration and core removal to break through the barrier and allow the soil to breath and drain.