Thatch

A dense, intermingled layer of dead and living stems, roots, and other organic debris that builds up between the actively growing grass and the soil surface in lawns. A thin thatch layer (less than ½ inch) is beneficial, insulating soil and reducing compaction. Excessive thatch impedes water infiltration, harbours pests and diseases, and prevents roots from accessing soil. Dethatching (power raking or core aeration) manages thick thatch buildup.