Scarifying removes thatch, permitting air to enter the lawn surface and enhancing thatch degradation by micro-organisms. Rake the lawn with a wire or spring-tined rake, or a powered scarifier, in two directions, one at right angles to the other. Moss should be killed prior to scarifying to prevent it spreading to other parts of the lawn during scarification.

Slitting – A slitting machine comprises flat knife-like blades that cut slits through the thatch to a depth of 8-10 cm, allowing air into the soil. Hollow tining – A mechanical or hand tiner removes cores of grass, thatch and soil, making a series of holes across the lawn about 10 cm apart. The cores need to be filled with a sandy top-dressing to prevent them from closing.

Spiking – Achieved by using a mechanical or hand spiker or roller aerator, or a garden fork. Angle the spikes back slight to raise the turf gently, to encourage deep root growth by creating fissures in the soil.