Tips on How to Dethatch a Lawn

I’ve been helping lawn care companies and sports turf managers grow turf for over 40 years. Many of the lawn care professionals I work with call me or text me photos of lawns and commercial properties that appear to be suffering from some unknown issue. When visiting some of these sites, I often discover the lawn problem traces back to a thatch issue. Too much thatch can suffocate your lawn.

What is Thatch?

Thatch is a dense layer of organic material — including live and dead grass, roots, leaves, stems and weeds — that occupies the space between the soil and your lawn grasses. It acts as a nearly impenetrable barrier that blocks adequate amounts of air, water and nutrients from reaching the roots of your grass. It can harbor unwanted pathogens that cause potentially life-threatening lawn diseases that can cause irreparable damage.

Almost all lawns have it. A little bit of thatch is a good thing. It provides a soft cushion under your feet. Think of it as the backing on a rich, luxurious carpet. It creates surface resiliency, so you have a soft spot to land when you and your kids are rolling around on your lawn. It’s when that thatch layer becomes too thick that it begins to cause issues.

What Causes Thatch?

Over-caring for your lawn is the most common culprit. Too much fertilizer and water will work against you, not only by promoting thatch production but in other ways, too. So, ease off on doing too much. Three fertilizer applications on most lawns are plenty. And keep your lawn a bit on the dry side. Too much water can cause disease issues and shallow rooting.

Contrary to common belief, mulching clippings and returning them to your lawn does not cause thatch build-up. Clippings biodegrade very quickly, improving soils and returning nutrients to your soil. There is no need to bag them.

Some grasses are more prone to producing thatch than others. Kentucky bluegrass produces thatch more prevalently than other cool-season grasses in the northern U.S. Down south, zoysiagrass and some bermudagrasses will generate more thatch.

It’s a good idea to use lawn seed mixtures that include improved varieties. These cultivars generally produce less thatch than common or public varieties.

How Do I know if My Thatch is Too Thick?

Take a sharp-bladed shovel or utility knife and cut a section from your lawn. Notice the spongy, gnarly mat of semi-decomposed vegetation above the soil line. If that thatch layer is more than ¾-inch thick, you have a thatch issue. Sometimes, you can feel the thatch under your feet as you walk across your lawn. If it feels more like you’re walking on a mattress than it does your living room carpet, you may have a thatch problem.

How Do I Remove Thatch from My Lawn?

As previously mentioned, you can stay ahead of the game by preventing thatch from taking over your lawn care.

There are tools available that will help you manage excessive thatch. A dethatching rake is a short-tined rake with thin, sharp blades designed to dig into your turf and pull up thatch. There are machines available that you can tow with your mower or lawn tractor or attach to your lawn mower, too. These are our picks for the best dethatching rakes. You’ll get a rigorous upper-body workout using these tools. Removing thatch by hand is hard work.

Renting a power rake is the most effective way to remove thatch mechanically. This is an engine-powered walk-behind machine that consists of vertical knives that spin on a covered shaft. This removes the thatch and brings it to the surface. Going over your lawn two or three times in different directions will help you get as much thatch removed as possible. You’ll need to rake up the thatch debris and haul it away after you’ve completed the process. Although it takes some effort, it’s much easier than using a hand dethatcher. You’ll spend around $65.00 for a half-day rental or up to $100 for a full day.

There are liquid products available, such as Turf Titan Thatch Buster, that can be applied to your lawn that claim to remove thatch. My take on these is that they do have benefits, but expecting them to significantly reduce existing thatch may be an overstretch. Generally, these products work because they activate soil microbes in the soil that are directly responsible for its health. These beneficial bacteria and fungi work together to improve nutrient uptake and feed on organic material in or on top of the soil. They help build healthier soil, but manage your expectations when it comes to addressing a thatch problem. Using a meal-based organic fertilizer such as Safer Brand Lawn Restore Natural Lawn Fertilizer or Scotts Natural Lawn Food will feed your lawn and promote healthy microbial activity in the soil at the same time. In my opinion, this is the way to go.

How to Prepare for Dethatching Your Lawn

• Dethatch when your soil is moist but not soggy. Water your lawn thoroughly two days before you plan to dethatch.
• If you’re using a dethatching machine, be sure to mark any shallow irrigation lines, sprinkler heads or buried utility lines before starting.
• Mow your lawn before dethatching by lowering the cutting height a half-inch or so.
• If you rent a dethatching machine, ask the rental store to adjust the operating depth before picking it up. The blades or tines should be set to cut no deeper than 1/2 inch into the soil. Get detailed directions on how to use the machine. Remember that dethatching machines can be heavy, so transport them on a truck or large van and enlist a buddy to help you load and unload them.

After Care

• Dethatching will probably leave your lawn looking worse for wear for a few weeks. The result may scare you a bit. Regardless of which dethatching method you choose, bolster your lawn immediately with quality fertilizer and a deep watering. Dethatching is rather invasive to your lawn, but it will bounce back and thank you for it. After a bit of TLC, it will look better than ever.
• This is also a great time to overseed with a high-quality lawn seed. Consult with your local lawn extension for a list of high-quality turf varieties. This is a great time to introduce new genetics into your lawn- grasses that take less water, fertilizer and other inputs.