Thatch

Individual grass plants are always forming new parts and losing old ones. Thatch is the matted layer of dead and living stems, roots, and organic matter that forms in most lawns above the soil. Thatch is a natural part of growing turf, and a small amount is actually healthy. It conserves moisture and provides a source of new humus as it decomposes. In large amounts it can be harmful and should be removed periodically to promote better water and nutrient penetration into the soil.