Dealing With Thatch in the Lawn

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Q:  How do I prevent thatch build up in my lawn?

 A:         So far this summer we have been on the dry side and not had to worry much about our lawns growing too quickly. During summers with plenty of rain, it can be very challenging trying to prevent a lawn from quickly getting out of hand and over grown. When you combine mowing less frequently with quick growing grass, you end up with more grass clippings than normal. Leaving grass clippings in your lawn after mowing is actually beneficial for the soil and grass. Too much grass clipping left in a lawn, however, can create future problems called thatch.

Thatch is the accumulation of large amounts of grass clippings that create a dense, spongy layer of dead plant material at the soil surface. A small layer of thatch, less than ½ inch thick, is beneficial to a lawn because it decomposes, adds organic matter and nitrogen to the lawn and conserves soil moisture. A thatch layer more than ½ inch can begin to create more problems that outweigh the benefits.

A thick thatch layer can create several problems for a lawn. The thick layer can create a barrier that prevents water, fertilizer and pesticides from reaching the soil and plant roots. Thatch quickly dries out and is difficult to rewet which makes watering difficult. Overtime, grass roots and stems begin to grow into a thatch layer instead of in the soil which can lead to grass drying out quickly during dry periods and being less cold hardy throughout the winter.

How can you prevent thatch build-up during this rainy weather? The first step is to mow your lawn frequently and at the proper height. This can be a difficult task to complete when we have had very few sunny days around for the lawn to dry out enough to mow. If you have been unable to mow your lawn routinely, it will be important to rake up large clumps of grass clippings after mowing or to bag clippings while mowing. This will prevent clippings from turning into thatch and will avoid having large clumps block sunlight to the grass underneath. Other steps that can be taken to prevent thatch accumulation includes avoiding over fertilizing, especially with nitrogen, and keeping the soil pH at the correct level to encourage small organisms like earthworms, insects and microbes in the soil to break down thatch.

If you suspect you have a large thatch layer in your lawn, you can check by cutting a pie-shaped wedge of grass in your lawn and inspect the thatch layer found just above the soil surface. A layer that exceeds ½ inch in thickness is considered too thick. If you do have a thatch problem, there are a couple of things you can do. Dethatching rakes work well for small areas. These rakes have curved blades you can slide through the lawn to lift up thatch. Dethatching equipment that is power-driven may be needed for larger lawns. Dethatching machines can be rented from lawn care business and some hardware stores or you can hire someone to do dethatching for you. One using a dethatching machine will need to have some understanding on how to properly use it because improper use can heavily damage a lawn instead of helping it. After dethatching a lawn, rake up and remove the dead plant material along with thoroughly watering the lawn to prevent exposed roots from drying out.

Hopefully we will see some rain soon and if we do, keep an eye on the amount of grass clippings you have. If you have a large amount of clippings, consider raking or bagging them to prevent a future thatch problem in your lawn.

For your gardening, landscape, and lawn questions contact the Wayne County Extension Master Gardener Volunteer Plant Clinic on Mondays and Wednesdays from 10 a.m. to 1 p.m. The plant clinic is a free service open to any Wayne County resident that has home gardening questions. One can reach the Wayne County Extension Master Gardener Volunteer Plant Clinic by phone at 919-731-1433, e-mail at, or stopping by Room 100 of the Wayne County Extension Office (208 West Chestnut Street, Goldsboro). People contacting the plant clinic with questions are encouraged to bring samples and/or pictures that could help in reaching a solution. Extension Master Gardeners are trained volunteers with the Wayne County N.C. Cooperative Extension Service.

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Jessica Strickland is an Agriculture Extension Agent, specializing in horticulture for North Carolina Cooperative Extension in Wayne County. Horticulture program information can be found at // Forward any questions you would like answered from this week’s column to