What Is Thatching of Grass?


Many homeowners hope for a lawn that looks thick, plush and healthy, and they spend energy and money trying to make it that way. Part of the recipe for achieving this is helping your grass to thatch, or develop a tightly woven layer of roots and stems on the surface of the soil. However, excessive thatch can cause problems, including increased susceptibility to disease and drought.


Thatch is the layer of sod that exists between the green we see on the surface and the topsoil underneath. It is made of a tightly woven combination of living and dead tissues and organisms, including products from leaves and stems, and decay-resistant roots. An unhealthy amount of thatch accumulates when these tissues are produced faster than they decompose.

Thatch Improvement

A healthy degree of thatch in your lawn can improve its appearance and wear tolerance. If your turfgrass seems thin or spotty, there are a few strategies that encourage the development of thatch. These include allowing your lawn to get higher before mowing, and applying nitrogen generously in the spring. You may also improve the thatch of your lawn by choosing a grass that is known to produce dense, fibrous tissue underneath. Some popular grasses that quickly build healthy thatch include zoysia, bermuda and St. Augustine.


While thick grasses can quickly achieve a lush, even appearance, they can go too far just as quickly. When the thatch layer of your lawn gets too thick, it blocks water, fertilizer and air from reaching roots and soil. It also harbors pests and sometimes causes a "puffy" appearance in the turf. One way to determine if your lawn may be suffering from a thatch problem is to cut out a pie-shaped wedge of grass approximately 2 inches deep. If the thatch layer--the fibrous tissue between the grass the soil--is more than 1/2 inch thick, a program to control further buildup may be needed.


One of the best methods of thatch removal is core aeration. This involves going over your lawn with an implement that pokes holes in the turf and removes plugs of grass that are approximately 1/2 inch in diameter. These holes help the lawn to take in needed water, air and nutrients. Aeration can be done any time of year, but fall is the preferred time for many homeowners, because fewer weeds will take hold in the newly aerated lawn than in spring.

Fertilization and Pesticide

Some fertilization and pesticide use is necessary to keep your lawn healthy, but too much encourages root development that outpaces decomposition. The result is thatch buildup. The same ingredients that kill unwanted lawn pests also eliminate earthworms and microbes that are needed for thatch decomposition.

Keywords: thatch control, thatch accumulation, controlling thatch