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How to Manage Pests

The UC Guide to Healthy Lawns

Dethatching

What is thatch?

Thatch is the layer of living and dead stems, roots, stolons, and rhizomes between the green blades of grass and the soil surface. A thin layer of thatch (less than 1/2 inch thick) can be beneficial to the lawn because it helps to limit weed germination, reduce water evaporation, and protect from frost damage. However, thick thatch layers can prevent water, air, and nutrients from penetrating the soil, causing reduced root growth and increased potential for drought stress. Thatch also favors fungal growth and can harbor insect pests. Some turfgrass species, such as tall fescue and perennial ryegrass, do not produce much thatch. Other turfgrass species, such as bermudagrass, bentgrass, and Kentucky bluegrass, have creeping growth habits and rapidly build thick thatch layers.

Tips for preventing thatch build up


How to reduce thatch

Photo of thatch and soil

Statewide IPM Program, Agriculture and Natural Resources, University of California
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Agriculture and Natural Resources, University of California

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