Lawn Care

What is thatch?

What is thatch?

What is thatch?

Thatch is the layer of built-up plant material between the green top growth and the roots of grass plants. As a lawn grows, it sloughs off leaves and shoots leaving a mix of dead and living plant material, thatch forms at the base of grass plants. Some organic matter, such as small grass clippings or mulched leaves, break down quickly in healthy lawns, but other materials take much longer to decompose. When buildup outpaces breakdown, your lawn's thatch layer grows thicker.

Thatch can be beneficial in small amounts.

A thin thatch layer, less than 1/2-inch thick, is beneficial to lawn health. It can act as an organic mulch to help conserve soil moisture and protect against big fluctuations in soil temperatures. A thin thatch layer allows water, nutrients and air to penetrate into soil and reach waiting plant roots. But when thatch grows thick, grass suffers.

But, it’s a fine line to tread, thatch layers of one inch or more become barriers instead of benefits. Thick thatch blocks water and fertilizer, and grass roots get trapped in thatch, where they're vulnerable to heat, drought and stress. Water from irrigation can accumulate in the thatch layer, too, so grass roots suffocate from lack of air. Thick thatch also provides a breeding ground for lawn diseases and insect pests.

Which kind of grasses are prone to thatch buildup?

Some lawn grasses are more prone to thatch buildup than other. Vigorous, spreading grasses such as Kentucky Bluegrass, Bermuda grass, and creeping fescues, may need regular dethatching. Clump-forming grasses, such as tall fescue or perennial ryegrass, seldom have thatch problems. Lawns with overly low soil pH or compacted soil are also prone to thatch.


Biological liquid dethatcher for lawns is a new category of product that makes it very easy to eliminate thatch from your lawn. You no longer need to use special thatch rakes or rent motorized dethatchers to clean up your lawn. Just buy a bottle of liquid dethatcher, mix it with water and spray on your lawn. Some products even incorporate fertilizer combining two jobs into one.

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