How and When to Dethatch a Lawn? – Complete Guide

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Tired of dead leaves browning out your green grass? Then you probably need to dethatch your lawn.

To dethatch lawn means getting rid of those unwanted grass clippings and leaves that stay behind after dying. As dead matter, they usually look brown and ugly.

Unlike mowing and trimming, dethatching is a little more complicated. It requires some sort of experience and following a few set of steps.

Here, we want to teach you how to do that. Whether you want to get rid of thatching on your lawn to make it green again, or just learn how to use a dethatcher for the first time – this is the article for you.

Take a look below and you’ll learn everything you want to know!

What Is Thatch? What Problems Does It Cause?

Thatch is every single leave, root, and crown of dead grass that stays on top or between the grass and the soil. Because it’s dead, this grass usually looks brownish, making the grass look duller than usual.

Thatch, however, is not necessarily harmful. It gives more bounce to the grass and often makes it look fluffier – which is ideal. Also, it insulates the grass and keeps it safe even in extreme temperatures. So you can say thatch is sometimes beneficial.

But when it starts growing too much and the grass doesn’t look green anymore – then it is problematic, to say the least.

Because thatching is dead grass leaves, rhizomes, roots, and stolons – it builds up to a thick layer. And this often happens when the organic part of the grass starts decomposing faster than the grass itself grows.

Thus, the grass gets covered with this dead organic matter, which turns vibrant green grass into brown & dull one. When this happens, you may not like the results at all.

Why? Easy – it can cause problems like these:

  • Makes it easy for fungi and insects to appear
  • Increases overall humidity in the grass body which could cause diseases
  • Prevents grass from growing as it limits access to sun, air, water, and nutrients
  • Makes the grass look brownish and disorganized
  • Damages the grassroots which could cause permanent growth issues

Over the long term, thatching can completely overgrow green grass and transform (in a wrong way) a lawn. That’s why it is so essential to prevent it. But first, you’ll have to know how it happens.

What Causes Thatch?

A brown and thick layer of thatch happens for many reasons. However, seven reasons stand out when it comes to thatching growing on a seemingly healthy lawn. Here’s what to know about them:

1. Overly-Thick & Compact Soil

The roots of most grasses need proper air to grow. If the roots are too tight or on a tough layer of soil, air can’t go through them, causing the grass to grow slower and die faster. This is the perfect behavior for thatch to grow.

2. Too Much Fertilizer

Grass needs fertilizer to thrive. It is recommended to use it on newly growing grass. But because fertilizer accelerates growth exponentially, adding too much can cause over-growing. And thus, the grass starts dying faster while decomposing slowly, which ends up causing thatch.

3. Too Much Acidity

Acidity changes the pH levels of the soil. The wrong pH trumps the healthy growth of microorganisms that aid in thatch decomposition. As the University of Kentucky Extension Service confirms, pH levels below 5.5 inhibit these microorganisms, causing more thatch.

4. Too Much Pesticide

Similarly to adding too much fertilizer or letting the pH levels go too low, pesticides can also cause thatch growth. Some fungicides will not only suppress microorganisms growth (like earthworms) but also promote turf rhizome and root growth. Thus, it makes it easier for thatch to develop.

5. Lack of Earthworms

You wouldn’t think earthworms are helpful when reducing thatch – but they are. Because earthworms dig tunnels underground, they help capture oxygen in the soil. This oxygen is used by the grass to promote healthy growth and decompose dead material faster. Without it, thatch is likely to happen.

6. Wrong Grass Species

Some grass species like Kentucky bluegrass grow too fast and produce stems that don’t break down quickly. When combined with other grasses, it produces thatch. This type of thatch prevents roots from reaching the soil, water, air, and reduces the effectiveness of fertilizers and pesticides.

7. Wrong Watering

It seems counterintuitive, but it happens. If you water the grass too lightly or too much – there’s a high chance you’ll experience thatching. Little water dries up the grass faster and keeps it in the high soil. Too much water makes it grow too quickly. Both make it easy for thatch to develop.

Signs You Need to Dethatch Lawn

You shouldn’t start dethatching your lawn unless necessary. But how do you know it’s time to do so?

Well, we’re going to teach you how you can realize it’s time.

The first thing you need to do is to dig inside the lawn. You need to look into the surface, leaves, and crowns, but also a little deep into the root. Here, you’ll know the grass needs dethatching if:

  1. The thatch looks dry and brownish
  2. There’s too much footprint happening
  3. You see clear signs of diseases 
  4. There are way too many insects (ants, chinch bugs, etc.)
  5. Grass breaks down too easily 
  6. Clear signs of grass dying due to extreme temperatures

If you see any of these things happening in your lawn, there’s a high chance you need to dethatch. However, be careful when and how you do so.

When to Dethatch Lawn

Now that you’re aware of the signs a lawn needs dethatching, it is time to learn how.

You’ll be happy to know that there’s no specific plan to follow – but it is heavily recommended to dethatch lawns depending on the type of grass you have.

For example, some grasses are ideal for cold seasons. For excellent results, you need to start dethatching in the spring or late summer. This will help them grow in their most active times. Some types of cool-season grasses include Kentucky Bluegrass, Fine and Tall Fescue, and Ryegrass.

In contrast, grasses for warm seasons are more likely to grow in summer times. So you must dethatch them precisely before they start growing. Some warm-season grasses include Bermuda grass, St. Augustine grass, Zoysia grass, Buffalo grass, Centipede grass, and others.

Even though the right season can be a perfect reason to start dethatching, we still recommend not doing so if the grass isn’t healthy enough or is under stress from pests and extreme climates. You may end up damaging the grass turf permanently, inhibiting growth, and preventing it from recovering.

How to Prepare for Dethatching

Because lawns need to be dethatched in suitable seasons, so you should dethatch at least 1 week before the climate gets to its ideal level. That will set the newly growing grass to benefit from the perfect conditions.

According to the Virginia State University Extension, you should start watering down two days before the dethatching. This will soften up the soil. And it will make it easier for the thatch to come off.

Then, you’ll be ready to start passing the dethatcher over it.

Dethatching Methods & Machines

So you found out the lawn needs some dethatching – but you have no idea how to proceed. Well, no need to worry.

To dethatch lawn, you need to consider how much thatching you want to get rid of. At the same time, you need to consider the type of grass, the elevation of the terrain, and its thickness.

But overall, they perform similarly. Typically, you’ll find metal pieces that help lift the thatch off the ground. Here are a few of these machines we’re talking about:

Vertical Slicer

Like the name says, a vertical slicer gets rid of the thatch by slicing it up vertically. It literally pulls the thatch from the floor, leaving the grass behind.

Because vertical slicers are similar to mowers, they also trim some of the grass away. And if they’re set up low, they can bring up some of the soil out.

A vertical slicer is ideal for light dethatching. However, it can still get deep enough to harm grass and other plants. So it should be used with care.

Power Rake

dethatch lawn

In case you want something a little more powerful, then you can use a dethatching rake. These can handle a lot of thatch but are often more damaging to the nearby plants.

A power rake can pull away enough thatch and dead grass to get rid of even the deepest thatch. Along with adjustable blades, power rakes can remove tons of thatch per operation.

You can hook a power rake to a mower or tractor for more effectiveness.

Slit Seeder

If you want to get rid of thatch like a professional, then you’ll use a slit seeder. These are massive machines that resemble mowers, with groovy circular blades that pull up thatch like no other.

A slit seeder can pull up the highest amount of thatch. And sure enough, you can use them in both small and big gardens with ease. You’ll just need to rake the leaves and thatch later on.

Here’s an idea of how slit seeders work and how to use one:

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Sod Cutter

In case you want maximum power, then you go for a sod cutter. This is the most effective lawn dethatcher you’ll find. Yet, it is mostly recommended for lawns where the thatch reaches 1 inch in height or more.

The problem of a sod cutter is the depth it achieves. In contrast with other machines, a sod cutter will thoroughly remove the thatch and grass. So you’ll probably need to renovate the lawn.



In case you don’t want to go deep into your lawn and renovate it, then you can use an aerator. It is probably the most effective yet harmless way to get rid of thatch.

The benefit of an aerator is the ability to open holes within the soil and grass to increase airflow. This brings more nutrients to the grass and removes some of the thatch. But it doesn’t eliminate large quantities.

How Much Does Dethatching Cost?

It depends on the machine you’re going for – and whether you’re doing the job yourself or paying someone else.

For example, a slicing dethatcher can cost anywhere from $40 to $400. A push slicer will be in the low two digits, but a tow-behind model with generous width can go over a few hundred.

A non-motorized pull behind dethatcher rake can go up to $100. But you can find models as low as $35 or even less. The largest models can reach a few hundred.

A motorized dethatching machine like a slit seeder or sod cutter can be in the low hundreds but can reach up to several thousand. You find them anywhere between $50 for a small and low-quality model, up to $3,000 or even more.

If you’re hiring a dethatching service instead, you may end up paying about $100 per day of work.

Should I Dethatch Lawn by Myself or Call a Professional Dethatcher?

As you can see, hiring a professional dethatcher to do the job for you can be expensive at first. But it can save you tons of time and effort.

Getting your own lawn leveling rake and dethatching yourself can suck some of your time and be exhausting, but it will save you hundreds per day of dethatching.

So it all comes down to your needs.

If you’re willing to spend the time learning how to use a professional or good-enough dethatcher, then you should handle the job yourself. This will allow you to get the job done as you need and prefer.

But if you don’t have the time or energy to get the job done, then a professional can always be your best bet.

A massive advantage of hiring someone experienced for your dethatching needs is that you won’t have to get the dethatcher. So even if they cost a lot at first, they will save you the money of getting a dethatching machine.

What to Do After Dethatching?

Dethatching will kill some of your grass. That’s inevitable. 

But that doesn’t mean you have to let it sit that way. That’s why we recommend raking away the leaves and thatch, reseeding, and dressing up the lawn once again. In short, you’ll have to renovate the grass after every dethatching operation.

It depends heavily on the type of dethatcher you used, of course. The most disruptive ones, like the sod cutter, will leave the lawn in an unpresentable way. In this case, you’ll need a complete renovation. But if you use an aerator, then you may only need to cover up a few places, and that’s it.

Whatever you do, always make sure you add some new grass, some topdressing, and fertilize the lawn (if required).

If you do this in a suitable season, then you’re likely to enjoy a beautiful lawn once again in no time.

How to Prevent Thatch from Returning

So you want to keep thatch from eating away your green grass? Well, you may need to follow these tips:

Seed the Ideal Grass

Remember, some grass species like the Kentucky bluegrass tend to grow aggressively and over-establish themselves. That means they are likely to create thatch even with the proper care.

If you want to prevent this, then make sure to use less intrusive types of grass like Bermuda, Ryegrass, Fescue, Buffalo, Bahia, and Zoysia grass.

Test the Soil Consistently

Make sure the pH and nutrient levels of the soil are at the right level. Too much acidity, limited nutrients, and over-fertilization can cause thatch from growing faster. Prevent all that by testing the ground periodically.

Mow & Irrigate Properly

If you know how to mow correctly and when to do so, then you can reduce thatching exponentially. Similarly, if you water the grass depending on the species (not too much or too little), then thatching is also less likely to happen.

Don’t Use Much Fertilizer or Pesticides

Lastly, if you over-fertilize the soil, you’ll end up changing its pH, over-feeding it, and probably even attracting animals. Similarly, if you use too much pesticide on the lawn, there’s a high chance you’ll end up getting rid of the healthy microorganisms and nutrients that prevent thatching. So be careful.

Bottom Line

As you can see, dethatching a lawn is not as easy as it seems. It requires effort and time, and probably some machines that you’ll need to learn how to use. And if you decide to hire someone else – it can be pretty expensive.

At the same time, it is an essential thing to do. And if you want to keep the lawn free of thatch later – then you’ll want to take good care of it.

However you proceed, make sure thatching doesn’t harm your lawn further. Use this guide and you’ll dethatch your lawn correctly, with fewer issues.

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