When to Dethatch Lawn — (Plus Dethatching Tips)

Last Updated on May 16, 2022 by Grow with Bovees

Have you noticed a buildup of excessive roots, dead grass stems and organic matter in your lawn?

That’s thatch — a cross-section of soil, and grass roots that may be invisible to the naked eye, especially if you’re looking at your lawn from a standing height.

In fact, many lawn owners have no idea when to dethatch their lawn, or even what thatch is and how it may affect the overall health of their grass.

Removing this tightly interwoven layer of dead and living plant matter is not a necessity, but is highly recommended if you want to rejuvenate your lawn and let your grass breathe.

What is Lawn Dethatching?

Dethatching is the process of removing this layer of mostly dead stems, leaves and grass roots to replenish the soil with air, water, fertilizer, and essential nutrients.

Allowing thatch to accumulate reduces your lawns tolerance to drought, cold and heat stress, (extreme temperatures), and increases your turf’s susceptibility to lawn diseases.

Thatch buildup in the worst cases restricts the grass roots from growing into the underlying soil, meaning they only take root in the all the thatch sitting on top of the soil.

However, dethatching or physical removal of thatch will not necessarily benefit all thatch plagued lawns, sometimes your lawn may just be lacking the beneficial microbes it needs to naturally dethatch or prevent thatching.

healthy lawns look like this with lush thick green vegetation
Person cutting grass with lawn mower

What Causes Thatch Layer Buildup in Lawns?

A buildup of thatch is a good sign that your lawn is lacking beneficial microbial activity. It will continue to accumulate if your lawn’s ability to produce dead material (organic debris) surpasses the ability of the microorganisms to break down the dead material, which blocks the passage of air, water and nutrients into the soil.

There are myriad different reasons why thatch builds up in lawns, most notably:

  • Poor soil aeration and drainage
  • Compacted soil, especially with heavy clay soil with heavy foot traffic
  • Bad lawn watering practices
  • Using chemical pesticides
  • Cold soil temperatures
  • Not carrying out proper lawn care

How Do You Know if Your Lawn Needs Dethatching?

Dethatching can be a daunting task, which is why it’s highly important that you assess your lawn to determine if you have a thatch problem, to begin with.

How Much Thatch Is Too Much?

A thick layer of thatch that’s thicker than 1/2- to 3/4-inches is considered excessive, which means you’ll have to dethatch physically.

You can even see the thatch layer by combing your fingers through the grass, and checking to see if you can see any soil between the grass plants. If you don’t see any soil between the blades, then it’s time to take your lawn care to the next level, and prepare to dethatch.

Another way to check if you have a thatch problem is to poke your fingers between the blades of grass to see if it feels springy or spongy. If it does, then you can cut a vertical slice from the turf, and measure the thickness of the thatch layer of dead grass with a ruler.

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The Best Time to Dethatch Lawn Areas?

Getting back to the main question — when should you dethatch your lawn? Well, lawn experts recommend dethatching grass during the period when it is actively growing, and the warm temperatures of early spring.

However, the exact time to dethatch grass depends on the type of turf you have. Further, for the best results you should dethatch your grass after mowing it a couple of times to about half its normal height.

Warm-season grasses such as Bermudagrass or Zoysia grass should be dethatched in late spring to early summer, whereas cool-season grasses such as Kentucky Bluegrass, Fescue and Ryegrass are best dethatched in the late summer or early fall.

Cool season grasses, such as Kentucky bluegrass, ryegrass and fescue, can either be dethatched in early spring or fall.

 Should You Dethatch the Entire Lawn?

Many homeowners ask if it’s a good idea to dethatch the entire lawn in one go, and the short answer is absolutely not! In fact, by doing this, you risk removing too much thatch and soil from one area, and not removing enough from other areas.

This is why it’s highly important that you carefully inspect each area of your lawn, and take note of areas with excess thatch.

Dethatching vs Aerating Lawn

Aerating with a core aerator as opposed to dethatching may seem a preferable option to solving your thatch problems on paper, but they’re two completely different lawn care processes. Both procedures are geared towards creating healthy lawns and enhancing the breathability of the soil and the ability of the grass to soak up the essential nutrients, and promote root growth, but the two processes help your lawn in different ways.

Dethatching, as the name suggests, is the process of removing thatch (leaves, grass clippings, flowers) from the soil surface. Thatch however does offer certain key benefits for your soil such as retaining soil moisture by acting as a mulch, providing a constant infusion of nutrients, as well as insulating the soil from temperature extremes.

Thatch only becomes a problem when the tightly intermingled layer is too thick, causing the grass roots to suffocate, thereby killing the healthy grass. Thatch that is too thick should be dethatched leaving only a healthy thin layer on the soil surface.

Lawn aeration is similar to dethatching in that it helps the soil under your lawn to breathe, but it is a procedure that helps ‘control’ thatch rather than actually get rid of an excessive build up.

There are a range of manual lawn aerators available to help you with the aeration of small lawns. If you have a large grass area to aerate, then you will likely need a more substantial machine, there are many pull behind aerator tools available to you.

Depending upon the size of your lawn, it may be better for you to think about core aerator rental rather than buying such a tool, there are rental companies in many locations where they have this service available.

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To explain briefly; aerating involves making holes in your compacted soil, (through any existing layer of thatch) in your lawn to allow essential nutrients (oxygen, fertilizer and water) to easily reach the grass root layer, whereas dethatching removes the layer of dead material that accumulates on top of the soil, thereby allowing the nutrients easier access to the roots of the grass plants. This will make the grass stronger, which, in turn, can help with weed control.

Tools for Dethatching a Lawn

It goes without saying that to dethatch your lawn properly, you need lawn care tools designed for the job. There are a number of tools at your disposal, from vertical mowers to power rakes to manual rakes.

Obviously, some of these are very specialized, so things such as vertical mowers could either be rented, or the work carried out by a specialist lawn care company who offer lawn dethatching as a service.

As they do a large volume of this type of work, they’ll have things like a vertical mower and power dethatchers to hand. Plus, they dethatch lawns for a living, so they’ll likely do a much better job than you will! They would also be happy to aerate your yard at the same time, no doubt. That leaves you with just having to fertilize your lawn, and regular mowing to worry about.

How to Use a Dethatching Rake to Pull Out Thatch?

Often referred to as a thatching rake, a walk behind power dethatcher is not the same as a leaf/lawn rake.

A dethatching rake is quite substantial and features sharp teeth on both sides of its head that can dig in between the grass blades, whereas the leaf rake, or dead grass rake has tines that fan out in a triangle on one side and is lightweight so that it can be passed over the surface of the grass to gather leaves or grass cuttings without digging into the turf and disturbing the roots.

It is used by pulling it through the grass towards you to pull up the thatch, then pushing it away from you to remove the thatch from the blades, ready for the next pull.

How to Use a Dethatcher to get Rid Of Thatch

A lawn dethatcher is a small machine that’s fitted with spring tines, which rotate and dislodge the thatch layer. Dethatchers are a great choice for less than half an inch thick thatch, and are easy to use. You just start up the machine, set the blade height and then simply pass it over the areas of grass that need dethatching.

How to Use Power Rakes to Remove Thatch

If you have more than a half inch thick thatch layer, then a power rake is the tool you need. This tool can remove up to four times the amount of lawn thatch compared to a dethatcher, but should be used early, as it can be very unforgiving on your lawn.

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Power rakes work by loosening the thatch using spinning flails that spin at a very high speed. The thatch that is loosened is then picked up by the tool, leaving your soil much more exposed than before. Before you power rake your lawn, it’s a good idea to run a test pass on a small area, and then another test pass, where both are in different directions.

These are expensive items to buy, and don’t see much use in a regular size yard, so maybe you could make inquiries with your local TruGreen lawn care franchise or independent lawn care service provider, as this could save you some cash.

How Often Should You Dethatch Your Lawn?

The number of times you dethatch your lawn, for the most part, depends on the type of grass you have, and the growing conditions. Some types of grass such as Bermuda grass and Zoysia grass tend to produce more thatch, whereas cool season grass like Bluegrass and Ryegrass a moderate amount of thatch, and Tall Fescue produces the least thatch.

However, it’s worth noting that regardless of the grass type, your lawn will need dethatching probably once a year, or when the thickness of the lawn thatch reaches about half an inch.

You can also use dethatching blades on your regular lawn mower if your yard is medium-sized. Dethatching is unwarranted if the thatch is less than half an inch, and doing so at this height will possibly damage healthy lawn grass.

You also will not need to go to all this trouble if you install an alternative lawn material like ground covers or artificial turf!

How to Get Rid of Thatch Naturally?

There are a few things you can do to take out thatch without using any tools such as consistently keeping the soil moist under the layer of thatch. Having moist soil below the thatch increases the speed of decomposition of the thatch layer, while speeding your lawn’s recovery.

Adding to this, to help prevent thatch, it’s good practice to collect your grass clippings regularly until you get rid of the thatch. Keep tabs on your soil’s acidic level and ensuring that it isn’t too acidic could slow down thatch build up over time.

Final Thoughts

If you have thatch that’s over 1.5 inches deep, then you may want to consider digging up your lawn, and starting over with a grass that doesn’t produce a lot of thatch.

It is important that you refrain from fertilizing your lawn before dethatching, but do it after to help your lawn recover.

As the saying goes “prevention is better than cure”, improving your soil, so that it’s aerated and bioactive enough to allow the thatch to decompose is a great way of removing thatch naturally from grass.

So remember, come late spring to early summer for warm season grasses, and early fall for cool season grasses, when the good growing weather is over, dethatch your lawn!