What Is Thatch & What Can Be Done About It?


Thatch build-up is one of the most common lawn problems that most people encounter. But the problem is not obvious from the surface, although the symptoms will be. Thinning grass, bare or brown patches and weeds taking over the lawn can all be indications that you have a thatch problem. The best time to dethatch a lawn is early spring when the grass enters the peak growing season.

What is Thatch?

Thatch is the layer of decomposing organic material that naturally builds up between lawn turf and topsoil. Healthy lawns need the vital nutrients that are provided by the decomposing roots, grass clippings and leaves found in thatch. But the thatch layer should only be about half an inch thick. Any more than this and it can block air and water from reaching the soil. This in turn causes the lawn to thin out or discolor.


Removing a piece of turf from the lawn is the best way to see how much thatch you have. Use a garden spade to cut out a section of turf that is about 6 inches square by 6 inches deep. The light brown material just below the grass is the thatch layer. Measure the depth of the thatch. If it's more than 1/2 inch thick, it's time to dethatch. Be sure to replace the turf when finished.

Hand Dethatching

Dethatching by hand is just plain hard work and should only be considered for very small lawns or patches. The lawn should be cut very short and the clippings removed. Then a special thatching rake is used to cut through the thatch layer and pull up as much material as possible. The hardest part of the job is maintaining enough pressure on the rake to keep pushed into the thatch layer while pulling back to tear it out.

Mechanical Dethatching

Many tool rental outlets have dethatching machines available by the day or half day. However be forewarned that these machines can be hard to control for the first-time user and can easily remove more thatch than necessary. A better option is hiring a landscaping contractor who offers power raking or vertical cutting services. They will also be able to aerate the lawn after dethatching. Aeration brings deeper microorganisms to the surface where they can accelerate thatch decomposition.


Establishing a regular lawn maintenance program is the best way to prevent thatch build-up. Aerating your lawn every spring is a key element of the plan. Aerators are machines that pull short cores of turf out of the lawn to allow better air flow to the soil. This prevents the soil compaction and stimulates microorganism activity. A yearly addition of sand and grass seed also helps to maintain both healthy soil and turf.

Keywords: what is thatch, lawn thatch, removing lawn thatch

About this Author

Based in Surrey, British Columbia, Stephen Oakley is a freelance writer focusing on environmental issues, travel and all things outdoors. His background includes many years spent working in the Canadian wilderness and traveling worldwide.