Thatch grass refers to a layer of organic material that accumulates on the soil surface, primarily composed of dead grass, roots, and other plant debris. This layer can hinder water and nutrients from reaching the soil, potentially affecting the health of the lawn or garden. Proper management of thatch is essential for maintaining a healthy lawn. Excessive thatch can lead to problems such as poor drainage and increased pest issues. Regular practices like aeration and dethatching can help control thatch buildup, ensuring that grass receives adequate air, water, and nutrients for optimal growth.