How to Dethatch a Lawn

Two Methods:Mechanical dethatchingManual dethatching

Managing thatch is an important component of maintaining a healthy lawn. Thatch, which is a woven layer of decay resistant stems, roots, rhizomes, and stolons, may prevent a lawn from receiving the proper nutrients and air. A lawn with a heavy thatch is more susceptible to bug and disease, it may take in more water, and fertilizer is less effective. Lawns should be de-thatched to promote healthy grass growth whenever the layer of thatch is more than 1 inch (2.54 cm) thick. You can do this either mechanically or manually.

Method 1
Mechanical dethatching

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    Check for presence of thatch.
    • Look at your lawn and ask yourself these questions: Is the lawn green on top but brown on the bottom? Does it look brown and dead after it had been mowed? Does the lawn feel "spongy" when walked on? If you answered yes, your lawn may have a thatch problem.
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    • Use a spade or knife to remove a small section of lawn in a few places around the yard.
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    • Measure the thatch layer. If it is greater than 0.5 inches (1 cm), your lawn needs to be dethatched.
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    Chose the proper time to remove thatch. This should be in the spring or fall when there is adequate moisture in the soil.
    • Water the lawn lightly 2 days before de-thatching. Trying to de-thatch a lawn that is too wet or too dry will damage the soil.
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    Mow the dethatched area to a grass height of 1 inch (2.5 cm).
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    Rent a power dethatching machine such as a vertical mower (power rake) or core aerator from your local hardware rental center.
    • Vertical mowers, sometimes called power rakes, chop down through the thatch layer and lift it to the top of the lawn. These machines create a lot of debris that will you need to remove for compost or disposal.
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    • Core aerators pull soil plugs from the lawn, which you can remove or leave on the lawn to decompose naturally. If you rent a core aerifier, have the store operator adjust the teeth spacing of the dethatcher to the appropriate spacing for your type of lawn. Blade height should be about .25 inch (.64 cm) above a hard, flat surface.
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    Make 2 perpendicular passes over the entire area with the core aerating machine or vertical mower.
    • For example, power rake the entire lawn running north to south. Do the next pass east to west. This will thoroughly break up the thatch on the lawn.
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    Remove the debris created by a vertical mower or core aerator with a leaf rake, and load it into a wheelbarrow for disposal.
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    Water the lawn thoroughly to help the grass recover quickly from the de-thatching process.

Method 2
Manual dethatching

  • Small lawns that do not have extremely thick hatch zones can be de-thatched manually with a sturdy leaf rake if you have the time and energy.
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    Buy or rent a thatching rake.
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    Place the blades of the thatching rake into the lawn, pull it towards you, and break up the thatch. Place the thatch in a wheelbarrow for disposal.
    • Be careful not to pull up large amounts of green grass.
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  • De-thatchers can be rented from home improvement stores or equipment rental centers. They can be heavy, so you may need help transporting it. Ask someone at the location you rent the de-thatcher from to help you set the depth and blade spacing on the machine based on the type of grass you have and the thickness of the thatch.
  • The deeper the blades need to dig into your lawn to break up the thatch, the more soil and grass roots will be exposed. This causes more stress to your lawn and, as a result, the lawn will need more time to recover. Don't expect a beautiful lawn immediately after de-thatching. It will take a while for the grass to return to normal.
  • Do not fertilize your lawn within 45 days prior to de-thatching in order to minimize the amount of extra grass growth.
  • It's best to de-thatch your lawn just before its most vigorous growth cycle to help the grass recover quickly since it's growing rapidly during that period.


  • Avoid recreating a thatch problem by over fertilizing with nitrogen. Do not apply the fertilizer at a rate of more than 1 lb. pound per 1,000 square feet.
  • Do not compost thatch that has been treated with herbicides.
  • Try not to use too many pesticides on your lawn, as they tend to decrease the number of earthworms and beneficial bugs in the ground.
  • Do not overuse composted or organic materials for topdressing.

Things You'll Need

  • Spade or knife
  • Ruler or tape measure
  • Power dethatcher
  • Thatching rake
  • Leaf rake
  • Wheelbarrow

Article Info

Categories: Lawn Care