A half-inch-thick layer of thatch, which is decomposing organic matter between the soil and upper grass, can be beneficial to your lawn. But if the thatch builds up, it can keep water and fertilizer from reaching root systems. It can also create problems in insulation, which makes it harder for your grass to withstand temperature changes. Use a thatching rake or dethatching machine to remove buildup.
For warm-season grass, you may need to wait to aerate and dethatch the yard until spring, when grass starts growing.
