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How Do I Dethatch?

by Dawn West, All About Lawns Columnist

Once you determine that you need to dethatch your lawn, the next step is to figure out how. As previously stated in the section on aerating, aerating can be a better alternative to dethatching if your lawn does not have excessive amounts of thatch (usually 1 inch or less). However, if you have thatch in excess of 1 inch, or just decide to dethatch anyway, here are a few things to remember when you do:

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  1. There are typically two ways to dethatch your lawn:
    • One, Manually with a leaf rake (shown), garden rake, or thatching rake.
    • Two, with a Power Dethatcher (vertical cutter). Smaller to medium sized lawns can be manually dethatched, assuming that you have the time. Manually dethatching, although time consuming, tends to be less stressful on your lawn and its appearance afterwards compared to Power Dethatching. In general, if your thatch does not exceed one inch, you can get away with dethatching manually or simply aerating your lawn instead.
  2. If you decide to use a power dethatcher, there are a few things you should do first. Before you begin, you should mow your lawn to about half of its normal mowing height. Second, you will need to either rent a dethatcher or hire a somebody to do it for you (see: Lawn Companies & Services in your Area). Much like aerators, power dethatchers resemble power lawn mowers in that they usually have engines that sit on top and wheels. However, instead of one horizontal blade to cut grass, dethatchers normally have numerous vertically aligned blades that can cut to the surface of, or even slightly into the soil. They are also VERY heavy and will usually require more than one person to transport. It is important to remember that if you are NOT experienced in dethatching, you may want to consider hiring somebody who is. The reason for this is that power dethatchers have numerous vertically aligned cutting blades that need to be calibrated to the correct height for each type of grass. For a dethatching service in your area, see: Lawn Companies & Services in your Area.
  3. If you rent a dethatcher from a lawn company in your area, you will need to set the depth and blade spacing. Usually, the location you rent it from will help you with this. However, in many cases, the depth of the blades are usually set to cut up to 1/2 inch into the ground (soil) to remove the thatch and scratch and stir the surface of the soil. For blade spacing, tougher and warm season grasses such as Bermuda typically require around 1-2 inches. For other thinner and more delicate grasses, the blade spacing is typically increased to around 3 inches and the blade height is usually set higher as well. Once you get a hang of it, you can make adjustments as you go. Remember to make a few passes with crossing patterns for better coverage.
  4. Once you are finished, be sure to remove all thatch and debris from your lawn. Unlike aerating, dethatching is almost strictly for the removal of thatch and debris. Removal can usually be done with a simple leaf rake.
  5. Once your lawn is dethatched, it is usually a great time to fertilize your lawn and/or reseed it. Remember, the greater the cut into the soil and thatch removal, the greater the soil exposure, especially to the grass roots. If you decide to reseed, follow-up by ranking the suspended seeds into the soil, add fertilizer, and apply a light covering of matter and/or sand. Additionally, it is a good idea to give your lawn extra watering after dethatching, especially during times of high heat and droughts.
  6. A final note: Dethatching is NOT a pretty process. It is analogist to the old saying, "Out of chaos comes harmony." The deeper the blades cut into your lawn, the more stress, and hence, the greater the recovery time for your lawn. In short, your lawn can look pretty bad after a deep power thatching. But remember, if you dethatch just prior to the grass's prime growing season, then it should recover rather quickly. If not, "The yard God" next door might have another reason to give you grief!

About the Author
Dawn West B.A. holds a B.A. in English from Harvard University and teaches writing at Oregon State University.

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