UC IPM Online UC ANR home page UC IPM home page


SKIP navigation


How to Manage Pests

The UC Guide to Healthy Lawns

When to dethatch


If your lawn has a bouncy feel to it when you walk on it, thatch is probably building up. As a general rule, plan to dethatch your lawn when the thickness of the thatch is more than 1/2 inch deep. To determine the thickness, remove a small square of your lawn to a depth of about 3 inches and measure the brown layer between the grass blades and the soil surface.

For both cool and warm-season grasses, the best time to dethatch is mid-to-late spring or early fall. During this time when the turf is actively growing, the grass will quickly recover from injury.


The frequency of thatch removal depends upon how fast the thatch layer builds. Lawns that are overwatered, overfertilized, or growing on heavy clay soils may accumulate thatch quickly. Turfgrass species is also a factor. Grasses such as bermudagrass, bentgrass, and Kentucky bluegrass build a thick thatch layer over several months and may need to be dethatched yearly. Grasses such as tall fescue and perennial ryegrass do not produce much thatch and may not need to be dethatched more than every few years.

What to watch out for

Avoid dethatching when weeds are germinating to prevent them from invading your turf. If you are planning to apply preemergence herbicides, do so after dethatching. Otherwise, the herbicides may bind with the thatch and decrease their effectiveness.

Photo of dethatching a lawn

Statewide IPM Program, Agriculture and Natural Resources, University of California
All contents copyright © 2016 The Regents of the University of California. All rights reserved.

For noncommercial purposes only, any Web site may link directly to this page. FOR ALL OTHER USES or more information, read Legal Notices. Unfortunately, we cannot provide individual solutions to specific pest problems. See our Home page, or in the U.S., contact your local Cooperative Extension office for assistance.

Agriculture and Natural Resources, University of California

Accessibility   /TOOLS/TURF/MAINTAIN/thatchtime.html revised: June 21, 2016. Contact webmaster.