Landscaping: How to Dethatch Your Lawn

Landscaping: How to Dethatch Your Lawn

You want your lawn to be the envy of the neighborhood; but when you look out the window, all you see is brown, thin grass. Definitely not the lush lawn you were after. What should you do? The first step is discovering the underlying problem: Is the thatch too thick? Is your soil compacted?  Do you need more growth? Each one of these issues can be resolved with the right approach. Let’s look at what to do if your thatch is too thick.

What is thatch?

Thatch consists of organic material, both living and dead, which forms between the grass blades and the soil. Thatch can act like mulch, keeping your lawn moist and protecting it from temperature extremes. However, when thatch is too thick, it causes the grass to suffer from lack of air and nutrients. A healthy layer of thatch is ½ inch thick; anything more than 1 inch will block water and nutrients from reaching the soil and will make your grass vulnerable to disease and pests.

How Do I Know If My Lawn Needs to be Dethatched?

Not all lawns need to be dethatched, so how can you tell if your lawn needs it? If your thatch layer is 1-2 inches thick, often the grass blades will have poor coloring. Try to stick your finger into the soil. If your lawn feels spongy or if you cannot easily stick your finger down into the soil, you need to dethatch your yard. 

How Do I Dethatch My Lawn?

1. Mow your lawn. Dethatching is best done after the second or third mow of the year.
2. Use a specialized dethatching rake for smaller lawns or rent a dethatcher for larger lawns.
   • The smaller dethatching rake has tines and curved blades that help loosen the thatch as you pull the rake upward. 
   • A dethatcher for larger lawns is also known as a power rake or vertical cutter.
     • A power rake has rotating tines that dig into the thatch to pull it up. This is best for lawns with thinner thatch layers.
     • A vertical cutter, or vertical mower, has vertical blades that dig into both the thatch and the soil. This is best for thick thatch layers. Be sure to adjust the spacing and cutting depth of the power rake before you start to dethatch.
3. Rake up and remove any loosened thatch.
4. Fertilize your lawn.
5. Keep your lawn thoroughly watered.

When Should I Dethatch My Lawn?

You want to dethatch your lawn when your grass is growing at its peak. Active growth helps stimulate grass recovery. For cool-season grasses, the best time of year is early spring; however, for warm-season grasses, late spring or early summer is best. You never want to dethatch when your lawn is dormant or stressed; this can damage it beyond recovery.

How Do I Prevent Thatch Buildup?

Test your soil every 3-4 years for optimum pH and nutrient levels. Aerate annually in order to improve the soil, and fertilize according to the recommendations for your grass type. The best fertilizer to use is a high quality, slow release fertilizer. Do not mow your lawn too short; the ideal length for blades is 3 inches. Mowing the blades too short can scalp the lawn, leaving it permanently damaged. Lastly, water the lawn thoroughly without over-soaking it. Too much water prevents the breakdown of beneficial organisms and promotes shallow root growth.

Sources: 

Pennington. 2019. “Why, When and How to Dethatch Your Lawn.” https://www.pennington.com

Scotts. 2021. “How to Aerate & Dethatch Your Lawn.” https://www.scotts.com