How To Dethatch

Thatch is a layer of organic material that builds up between the top growth of grass and the roots. Most of this material is composed of dead grass stems, roots and leaves that don’t properly decompose. While having a small thatch layer is essential to protecting the roots of the grass, too much can literally suffocate your lawn. An excessive thatch layer blocks moisture and air from reaching the roots, providing an environment that encourages disease and pests. Read on to learn how to properly dethatch your lawn.

How do I know if I need to dethatch?

If you have a serious thatch problem, it is usually evident just by walking on the lawn. If your lawn feels very springy and crunchy underfoot, you most likely have a thick layer of thatch lurking under the grass. The best way to test the thatch accumulation is to remove and inspect a plug from your lawn. Using a hand shovel, remove a 2-3″ thick plug of sod. If upon examination you see more than ½ inch of spongy, dry brown material, it’s time to dethatch. Note that many warm-season grasses such as Zoysia, Bermuda, St. Augustine and Buffalo grass are particularly prone to thatch buildup.

When should I dethatch?

Dethatching can be stressful for your lawn. It’s recommended that dethatching be done just prior to your lawn’s most vigorous growth cycle so the grass can heal and recover quickly. For cool season grasses such as Kentucky bluegrass, ryegrass and fescue, dethatching is best done in late August to early October. Be sure to give your grass plenty of time to recover before the first hard frost. For warm season grasses, dethatch in the spring after at least two mowings. Don’t dethatch when the soil is sopping wet, as dethatching may damage grass by pulling it out by the roots. Avoid dethatching when soil is very dry or during times of drought as well. Soil must be moist for ideal results. It’s also recommended that you mow the lawn half its normal height right before dethatching. This allows the dethatcher tines to reach the roots without excessive interference.

How can I prevent thatch from accumulating?

Again, certain grasses like St. Augustine, Bermuda and Zoysia naturally form thick thatch layers. You can help prevent excessive thatch buildup however, by loosening compacted soil through aeration. Also avoid over fertilizing with nitrogen, overwatering, and mowing too high. For more tips on how to dethatch your lawn properly, visit

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