How to Dethatch Lawns


As grass grows, it builds up a layer of dead stems and roots between the soil and the green grass. This dead layer benefits the grass as long as it is less than 1/2 inch thick. Once the thatch gets thicker than 1/2 inch, the thatch dries out quickly and keeps nutrients and water away from the grass plant. Dethatching removes the excess debris and stimulates the grass to grow healthy and strong. Dethatch your lawn in the spring or early fall while the grass is actively growing.

Prepare the Lawn for Dethatching

Step 1

Determine the thickness of the thatch by removing a plug of the lawn. Measure the brown layer of thatch above the soil. Dethatch the lawn when the thatch layer exceeds 1/2 inch in thickness.

Step 2

Remove furniture, hoses, rocks and other debris from the area. Mark the location of any buried cables or the sprinkler system, if you have one. You want to avoid hitting these with the dethatching machine.

Step 3

Mow the lawn to about 1 inch before dethatching. Make sure the grass is dry--don't dethatch when the lawn is wet.

Dethatching Small Areas

Step 1

Use a dethatching rake on small areas. Rake the area, making sure the rake is reaching down to the soil, then pull it upward to bring the thatch to the surface. Repeat this procedure across the entire area.

Step 2

Use a regular rake to gather up the thatch and clean up the area.

Step 3

Repeat the process twice a year, in the spring and fall. Water the lawn after dethatching and wait about one week before fertilizing with a good lawn fertilizer.

Using a Commercial Dethatcher

Step 1

Rent a flail-type dethatcher for larger areas. Move the dethatcher to a paved surface and adjust the blades to about 1 inch above the pavement. Read and follow all the safety instructions that are provided with the dethatcher, including wearing protective clothing.

Step 2

Start the dethatcher on slow speed until you are familiar with its operation. Go over the lawn the same way you would use a lawnmower, being sure to avoid the sprinkler system and buried cables. Stay on the grass and avoid steep hills.

Step 3

Make one pass only for most lawns. If your thatch is deep you may need to make a second pass.

Step 4

Rake up the debris and thoroughly water the lawn. Wait a week, then fertilize with a good lawn fertilizer.

Tips and Warnings

  • Dethatching when weeds are germinating allows them to invade your lawn. Use pre-emergence herbicides after dethatching if desired.

Things You'll Need

  • Lawnmower
  • Dethatching rake or dethatching machine
  • Rake
  • Lawn fertilizer


  • Clemson Cooperative Extension: Controlling Thatch in Lawns
  • Mowing, Dethatching, Coring, and Rolling Kentucky Lawns
  • The UC Guide to Healthy Lawns: When to Dethatch
Keywords: dethatch lawn, dethatching, commercial dethatcher

About this Author

Diane Watkins has been writing since 1984, with experience in newspaper, newsletter and web content. She writes two electronic newsletters and content around the web. Watkins has a Bachelor of Science degree in chemistry from Clemson University. She has taken graduate courses in biochemistry and education.