Lawn thatch comes from dead grass, leaves, roots and other organic material that can make the lawn look brown. Thatch on the lawn can prevent grass seed and fertilizer from reaching the ground, and blocks water, light and air. You can use a dethatching rake to remove the thatch. A dethatching rake has a double-sided rake head about 15 inches wide that is attached to a wooden handle about 54 inches long.
Mow the lawn. Grass 1 to 2 inches tall is easier to dethatch. The thatch will appear brown and thick. If you can see the ground easily through the thatch, it does not have to be cleared away. Thatch greater than a half-inch thick will not be easy to see through and should be removed to allow more light, water and air to reach the grass.
Look at the head of the rake. A dethatching rake (also known as a thatching rake) can be used to pull up thatch and to cultivate dirt. The side you want to use to pull up thatch will have slightly crescent shaped tines (teeth) when viewed from the narrow end of the rake head, and straight teeth when viewed from the long side of the rake head. The tines are also pointed.
Place the dethatching side of the rake at the location where you want to start. Pull the rake toward you and it will pull up the thatch. While standing in the same location, push the rake away from you and the rake self-cleans as the thatch is dragged off the tines.
Adjust the angle of the pivoting head if necessary by loosening the wing nuts. You can choose to reduce the angle of head if it is cutting too deep or if the thatch is so thick, it's too hard to pull through it with the head at a right angle to the handle. When the thatch is dense and tangled, you might need to make repeated strokes across the grass to pull it all out.
Continue pulling and pushing the dethatching rake in a fashion similar to vacuuming a rug. Overlap the previous section to ensure all the ground is dethatched. You can use a leaf rake to collect the loosened thatch.
Fill in low spots with soil and then use the opposite side of the rake to work the soil into the area.
Apply grass seed and water lightly so as not to wash away the seed. Continue to water every three days unless it rains and until the grass sprouts, which can be seven to 21 days.