DIY dethatcher lawn mower. How to Dethatch a Lawn and Why You Need To

How to Dethatch a Lawn and Why You Need To

David Beaulieu is a landscaping expert and plant photographer, with 20 years of experience.

Mary has been a Master Gardener for 30 years and a commercial and residential gardener for 50 years. She is a former Clemson University Extension Agent.

Power Rake Blade to Home Made Dethatcher

Dethatching a lawn is an easy DIY project because it can be accomplished with a simple rake.

What Is Dethatching?

Dethatching is the removal of thick thatch on a lawn. Thatch is a mat-like layer of organic materials, such as dead grass, rhizomes, mulched leaves, and other debris that has not yet decomposed.

When the layer of organic thatch becomes too thick and impenetrable, it’s time to dethatch your lawn. You should not overlook the importance of dealing with problematic thatch because the long-term health of your grass hinges on dethatching.

How to Detach Your Lawn

Any deep raking that you do is better than nothing, especially if you faithfully rake every year. Annual vigorous raking with a manual rake is a much better option than the potential damage caused when a power rake tears into a thick thatch layer. However, depending on how much thatch you have to contend with, there are various tool options to get the job done:

  • Leaf rake: An average manual fanned leaf rake is the simplest tool but all manual rakes can be laborious to use when dethatching an entire yard.
  • Rigid garden rake (bow rake): A manual rigid garden rake (bow rake) with a metal head and tines can be sturdier than a leaf rake to use for dethatching.
  • A convex or dethatching rake: This specialty manual rake is designed with a head with rows of straight-edged tines on both sides to clear dead matter in the lawn.
  • Power rake: There are types of power rakes that can be attached to either a walk-behind or towed behind a riding mower. Another type of motorized dethatching tool looks like a mini-mower that you walk behind to operate. They can be rented from a home improvement center. The blades will usually need adjustment to accommodate your type of grass.

Dethatching uses an action that is not much different than raking up fallen leaves. Once you’ve chosen a rake, take these steps to dethatch:

  • Use the rake to crisscross the lawn with a series of parallel passes.
  • As you rake, push the rake tines deeply down through the grass, so that they reach the thatch layer that lies beneath.
  • Clean up the massive amounts of loose thatch that are dislodged from the base of the grass blades.

What to Do After Dethatching

Dethatching tends to loosen up the soil at the base of the grass blades and reveal some bare soil where the thatch has been removed. This is a good time to overseed your lawn with additional grass seed and to apply appropriate fertilizers or soil amendments. Then water the lawn to relieve it from the stress of dethatching.

Core aeration is best performed immediately after dethatching, but before overseeding and amendment/feeding.


It’s a good idea to have a soil test done every few years and apply whatever amendments are recommended by the testing agency.

When to Dethatch Your Lawn

Once regarded as required yearly, dethatching is now approached more strategically, and many lawn-care experts caution against doing it too often. That’s because the hard, deep raking involved in dethatching can tear at grass roots and even open up the lawn to disease and pest problems. In addition, a moderate layer of thatch can be beneficial to:

  • Moderate soil temperature swings
  • Preserve soil moisture
  • Maintain a uniform soil pH of about 6.5, ideal for turf grasses.
  • Provide nutrients as organic material steadily breaks down
  • Block out burrowing pests

How do you know you have overly thick thatch? If the layer of thatch is over 3/4-inch thick, you may need to dethatch. The best way to measure thatch is to dig out a piece of lawn and measure the layer of dead, woody thatch between the soil and the blades of grass. Thick thatch may feel spongy underfoot, as well.

Dethatching is not nearly as common a lawn care project as mowing or fertilizing. Some homeowners may never need to dethatch the lawn. Or, it may be necessary only every few years. Also, some types of grass simply are not as susceptible to thatch build-up as others.

Cool-Season Grasses

Dethatching works best when the lawn is growing and the soil is somewhat moist. Cool-season grasses should be dethatched in the early spring or early fall. While Kentucky bluegrass (Poa pratensis) is one of the cool-season grasses prone to developing too much thatch, tall fescue grass (Festuca arundinacea) is far less susceptible.

Warm-Season Grasses

Dethatch warm-season grasses when they are growing in the late spring and early summer (after you’ve mowed once). Among the warm-season grasses, you are more likely to have to dethatch Bermudagrass (Cynodon dactylon) than zoysiagrass (Zoysia japonica).

Dethatching Lawn. How to Dethatch your lawn with a regular lawnmower. Quality Content Rick


New lawns, whether started from sod or seed, should not be dethatched for several years until they develop good root systems. Dethatching a new lawn can cause considerable damage, especially if it is done with power equipment.

Why Dethatching is Important

Dethatching a thick layer of thatch is important to help your lawn stay healthy and thrive. An overabundance of thatch blocks water and fertilizer from reaching your lawn’s roots. The layer of thatch can strangle and trap grass roots, resulting in poor growth from stress, disease, excess heat, and a lack of water, air, and nutrients.

But dethatching can cause significant lawn damage if it is done when it is not needed. There are several other reasons why you might want to avoid dethatching:

  • Vigorous dethatching exposes soil and causes faster moisture loss.
  • Dethatching can make it easier for lawn weeds to germinate.
  • Lack of thatch deprives grasses of essential nutrients.

Rather than assuming your lawn requires yearly dethatching, however, diagnose your lawn first to decide if the advantages outweigh the drawbacks, if you can prevent the problem from developing, or whether you need to perform core aeration, instead.

Preventing a Thatch Problem

Since a thatch problem is the result of new organic matter building up more quickly than the older organic matter can break down, avoid practices that result in your grass growing too quickly. For example:

  • Do not water the grass more than is necessary.
  • Do not feed the lawn with a fertilizer that is high in nitrogen.
  • Do not overuse pesticides. Worm presence helps in the decomposition of thatch.

Dethatching vs. Core Aeration

Don’t confuse dethatching with another important lawn care routine—core aeration. Although these activities are sometimes confused with one another, they are entirely different procedures. Performing core aeration does not dethatch the lawn, nor does dethatching offer the same benefits as core aeration.

Core aeration is a process of using a manual device to remove small plugs (cores) of turf with attached roots, leaving small cylindrical holes through which air can penetrate to the root layer. Regular core aeration can slow thatch buildup by introducing air and water into the thatch to speedily break down organic material.

Whereas dethatching may be harmful to your lawn, core aeration is beneficial and should be done every few years. Core aeration is especially valuable if the lawn is badly compacted, which can easily occur in yards with excessive foot traffic and sports activity.

When to Hire a Professional

Dethatching a lawn is not a complicated project, but it can be time-consuming and hard physical work, especially if it is a large lawn, the thatch layer is very thick, and dethatching hasn’t been done for many years. Because lawn-care professionals have the equipment to do this work quickly, it may make sense to simply hire someone to do this work, especially if you’re already hiring professionals to do other seasonal lawn-care work, such as core aeration. Pros familiar with using power dethatchers are less likely to damage the lawn than a homeowner using a rental tool for the first time.

Once you get into a routine of vigorously raking your lawn each fall or spring, dethatching becomes a much less difficult task and one that most homeowners will have no trouble doing themselves. If you are already raking up fall leaves, expend a little more effort to rake down to the thatch layer for a healthier lawn.

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How to Dethatch and Aerate Your Lawn

Lawn care is simple—mow, water, and fertilize. Done! Well, there are two more things most homeowners neglect to do, to the potential detriment of their lawns: dethatching and aeration.

Thatch: A Barrier to Healthy Lawns

Thatch is a layer between the grass and the soil made up of interwoven accumulated dead and living grass shoots, stems, crowns, and roots. It creates a barrier between the soil and the green grass you so adore. A thin layer of thatch is good—about a half-inch. It helps maintain steady soil moisture and temperature. It becomes problematic when it’s thicker.

Thatch can harm lawns. It’s difficult for water to penetrate a thick thatch layer, causing water to run off instead of soaking in. It can harbor insects and lawn diseases, and grass may begin growing in the thatch layer instead of the soil, producing shallow root systems and exposing it to greater temperature extremes. It can block air, nutrients, and pesticides from reaching the roots.

You can tell if your lawn has a thatch problem when water runs off the lawn instead of soaking and you’ll begin to notice grayish-brown matts. To determine how much thatch has accumulated, cut out a wedge of lawn about two-inch deep. It should be fairly easy to identify the thatch layer between the soil and grass.

Contributing to thatch build-up are the three things you already do to maintain your lawn: mow, water, and fertilize. Compacted soil can also contribute to thatch build-up.

Am I Harming My Lawn?

Overwatering and over-fertilization contribute to thatch build-up. It’s too much of a good thing. Although infrequent mowing may be good for you, it’s not good for your lawn. You need to find a healthy maintenance balance for your lawn. The goal is to maintain your lawn so that the accumulated plant debris can decompose at the same rate the grass grows. Mow at a height and frequency recommended for your variety of grass. Use the 1/3 rule when mowing—remove no more than one-third of the blade of grass in a single mowing.

Some believe grass clippings cause thatch, but they don’t. Grass is mostly water and decomposes fairly quickly and returns nutrients to the soil. Grasscycling provides free fertilizer. Using a mulching mower helps speed the decomposition of the smaller clippings.

Fertilize as recommended, using a low-nitrogen or slow-release fertilizer like Milorganite.

Best Time to Dethatch Your Lawn

The best time to dethatch depends on grass variety and location but is optimal when the lawn is actively growing and has time to recover. In the north, late summer or early fall before the grass goes dormant are good times to dethatch, and late spring in the south.

For small areas, you can use a hand dethatching rake. I’m talking about small areas. If you’ve got a large yard—even average-sized—you would have to reserve a work week using a dethatching rake and buy a box or two of Band-AIDs ® to tend to your blisters. Leaf rakes and hard rakes could be used, but they’re just not up to the task.

Thatch builds up over time, so it’s not necessary to dethatch every year. Plan on doing it every five years or so if your lawn needs it. You might want to give your lawn a quick check every year just to see how much thatch has accumulated.

Time your long-term dethatching and aeration (we’ll get to that momentarily) schedule. We recommend aerating your lawn every other year and dethatching in a year you’re not aerating.

Power Equipment for Dethatching Your Lawn

A dethatching machine has blades that cut through and remove thatch to the soil surface. Those with knives or blades are preferred over those that use rake-like tines. Rent a dethatcher from a big-box store or equipment rental company. They’re heavy, so you’ll need a truck and a friend or two to lend a hand.

Follow the manufacturer’s instructions for using the dethatcher. Make sure the lawn is slightly moist, but not wet. Rock-hard soil is difficult to penetrate. Go over your lawn once, like your mowing. If there’s a lot of thatch, you may need to make another pass in the opposite direction to remove it all.

You’re going to have a lot of material to rake and remove. Depending on the size of your yard and the amount of thatch, it could be a SIGNIFICANT amount. You can add the debris to your compost pile (You are composting, aren’t you?) or use it as mulch around trees and shrubs ONLY if it has not been treated with an herbicide. It’ll add organic matter to the soil as it breaks down. After raking, thoroughly water the lawn. Avoid a lot of traffic on the lawn, over- or under-watering, and chemical applications until normal growth has resumed.

Prepare yourself. Your lawn is going to look, well… terrible, awful, ratty, or ragged for several weeks after dethatching. If it does, you did it correctly!

Thatch builds up over time, so it’s not necessary to dethatch every year. Plan on dethatching every five years or so if your lawn needs it. You might want to give your lawn a quick check every year just to see how much thatch has accumulated.

Steps to Detaching Your Lawn

  • Timing. the best time to dethatch in the north, late summer or early fall before the grass goes dormant, and late spring in the south.
  • What tool to use? For small grass areas use a dethatching hand rake, and for larger lawns rent a dethatcher from a big-box store or equipment rental company.
  • How to Dethatch? Make sure the lawn is slightly moist, but not wet. Go over your lawn once, like you’re mowing. If there’s a lot of thatch, you may need to make another pass in the opposite direction to remove it all.
  • Thatch debris. Add the debris to your compost pile or use it as mulch around trees and shrubs ONLY if it has not been treated with a herbicide.
  • How often to dethatch? Plan on doing it every five years if your lawn needs it.

Aeration: Breathe Life into Your Lawn

The soil your lawn is growing in compresses over time. Compacted soil causes some of the same problems thatch does. The soil can become so dense water has a difficult time seeping in, grass struggles to grow, and roots gasp for air.

Aeration is the process of making holes in the lawn, which loosens the soil to improve drainage, making it easier for water, air, and fertilizer to reach the roots. It gives the roots some room to grow deeply. The result is a thicker, healthier lawn. Unfortunately, homeowners very often neglect this important maintenance practice.

There are two methods of aeration: tine or spike aeration, and core or plug aeration. Tine aeration uses tines to pierce the soil. Unfortunately, it can also further compact the soil; some don’t consider it to be aeration at all. Core aeration removes plugs of soil from the lawn and is the preferred method. Core aeration can also keep the thatch layer in check. Aeration equipment that’s pulled behind mowers tends to be ineffective.

When heavily traveled paths on the lawn start to look weak and there’s a thatch layer of an inch or more, it’s time to aerate. Lawns in good condition, with a half-inch or less of thatch, generally don’t need to be dethatched and should only need to be aerated every other year.

When and How to Aerate Your Lawn

In the north, aerate in early fall; doing it in spring can damage tender grass shoots. Avoid aerating in fall when the grass is dormant. In the south, aerate in mid-spring to early summer.

Rent an aerator from a big-box store or equipment rental company. No need to invest in equipment that takes up space and you’ll only use once every couple of years. Bring your truck and the same friends who helped you haul the dethatcher. (You may owe them a beer this time.) Consider sharing the rental cost with those same friends so they can aerate their lawns, too. Follow the manufacturer’s directions when operating the aerator.

Recommendations lean toward removing as many cores as possible—20 to 40 per square foot at a depth of 2–3 inches. Run the aerator several times in different directions if you’re not getting the recommended number of holes in one pass and loosen up highly compacted soil. Before you begin, mark sprinkler heads and anything else that may be damaged while aerating.

Core aeration will leave cores of soil on the surface of your lawn. Just leave them. They’ll break down, and the soil will work its way back down. Like dethatching, you may be a little embarrassed by how your lawn looks. It can take up to six weeks for grass to fill the resulting holes. Be strong. It’s going to look so much better.

After your lawn is breathing easier, it’s the perfect time to overseed and fertilize using a slow-release fertilizer like Milorganite.

If aerating or dethatching is a daunting task. Call a landscape maintenance company and save the beer for yourself.

Steps to Aerating Your Lawn

  • Timing. In the south, aerate in mid-spring to early summer, and in the north, aerate in early fall; doing it in spring can damage tender grass shoots.
  • What Tool to Use? Rent an aerator from a big-box store or equipment rental company.
  • How to Aerate? Run the aerator several times in different directions if you’re not getting the recommended number of holes in one pass, and loosen up highly compacted soil. Before you begin, mark sprinkler heads and anything else that may be damaged while aerating.
  • What to Do With the Soil Cores? Aeration will leave cores of soil on the surface of your lawn. Just leave them. They’ll break down, and the soil will work its way back down.
  • Feed Seed. After your lawn is aerated is a perfect time to overseed and fertilize using a slow-release fertilizer like Milorganite.
  • How Often to Aerate? Plan on doing it every year or two if your lawn needs it.

When and How to Dethatch Your Lawn

Ripping, tearing, slicing, slitting, cutting — all sound like unpleasant things to do to a perfectly innocent lawn. But if you have a dense underlayer of thatch keeping your lawn from doing its best, then your lawn will benefit from dethatching. We’ll explain what thatch is, how it develops, and how to free your yard from it and keep it from returning.

Just want a dethatching tool? Here are our top picks:

What Is Thatch?

Thatch is a tightly intermingled layer of dead and living grass shoots, stems and roots that accumulate above the soil and below the green vegetation.

A little bit of thatch is normal and even beneficial:

  • It gives turf a bit of a bounce, beneficial for little feet and golf balls.
  • A thin layer makes grass more resilient against wear.
  • It insulates soil and grass roots against temperature extremes.

Lawn thatch develops when the organic matter in grass produces more quickly than it decomposes. While a rapidly growing lawn sounds great, excessive thatch buildup leads to several problems:

  • Disease-causing fungi and insects are inside.
  • It holds on to humidity, which promotes disease.
  • It limits root growth, resulting in a shallow system of grass roots.
  • Movement of air, water and nutrients in the soil is slowed.
How Do You Measure Thatch?
1. Take a trowel

Dig out a two-inch deep piece from the lawn

Measure the brown spongy material between the dirt and the green vegetation

Common Causes of Thatch

People used to think thatch comes from grass clippings, Don Callahan with the Yamhill County Extension in Oregon says. But thick thatch is a result of other things:

  • Dead leaves decaying along with stems and roots
  • Roots growing in the thatch but not reaching the soil under it
  • Lateral shoot growth (aka stolons and rhizomes), something that can happen when thatch interferes with roots trying to grow down
  • Infrequent mowing. Lawns should be mowed weekly during the growing season, or, if you want to keep measuring, check out a full list of mowing heights for each grass.
  • Taking off too much at once: You want to follow the one-third rule or mowing, which says to remove up to one-third of the height of the grass (but no more!) per mow. Taking off too much at once places stress on the grass and can weaken it and slow its recovery time. If your lawn is too tall, take down the height over several mows.
  • Excessive water: Giving the lawn too much water or having wet soil (often caused by drainage problems)
  • Dry soils, when it is chronic or when the thatch is keeping water from getting through
  • Pesticides used on a regular basis, not as needed. Plus, they can kill earthworms, which stimulate the breakdown of thatch.
  • The type of grass matters. Some turfgrass species produce a lot of stem tissue: Cool-season grasses to watch include Kentucky bluegrass, creeping bentgrass, and creeping red fescue. Conversely, perennial ryegrass and tall fescue do not produce significant thatch build up.

When to Dethatch a Lawn

Warm season grasses should be dethatched in the late spring or summer, cool season grasses in the late summer or early fall. These times correspond with their annual growth spurts and favor Rapid recovery. That means three or four weeks of good growing weather (at least) after the dethatching.

Which grass type do you have? Cool-season lawns are most often grown in the upper U.S. Warm-season grasses thrive in warmer regions, such as in the South and along more southern or coastal areas.

  • Bahiagrass
  • Bermudagrass
  • Buffalograss
  • Carpetgrass
  • Centipedegrass
  • St. Augustinegrass
  • Zoysiagrass

Preventing Thatch Buildup From Returning

Dethatching Tools: A Guide

Dethatching machines come in various forms. And although some lawn services and rental companies use the terms interchangeably, the machines perform dethatching by different means, with varying levels of intensity.

What they have in common are spinning metal pieces that pierce and lift the thatch from the lawn. Some employ slicers, others metal tines (experts recommend the former as more effective). Some are stand-alone, powered units, others are made to be dragged behind a tractor or riding mower.

Here are some of the most common dethatching techniques, and the power dethatchers that perform them.

Core Aerator Aeration is an option for lawns with a mild amount of thatch. A core aerator will pull up plugs of sod and soil, which can provide space for nutrients and grass roots to penetrate beneath the thatch layer. However, you can’t aerate to remove large volumes of thatch.
Power Rakes Power rakes attack serious thatch. Using a power rake carries some risk to the lawn since they can pull up live plants along with dead grass. They come with adjustable flail blades that allow deep penetration into the lawn.
Slit Seeders These are all-in-one machines owned by some professional lawn care companies. They have one set of spinning blades that dethatch, then another set of circular blades that lay down grooves. They can have tines. They dethatch and plant grass seed in a single pass. These machines will lift a large volume of thatch — even on small lawns, it can produce enough to fill several lawn bags — that needs to be gathered up with a rake or lawn mower with the mulching unit attached.
Sod Cutter These machines are for the most-serious thatch problems — 1 inch or more. They have thick blades that cut through to the soil surface and allow you to remove sod in strips. You need to completely renovate the lawn if using a sod cutter.
Vertical Slicer Vertical slicer or verticutting machines slice through the lawn to pull up thatch. Often used on sports fields, set the vertical lawn mower low enough to leave some soil on the surface of your lawn. It should cut about a quarter-inch into the soil after the grass blades have gone all the way through the thatch layer. Hand rake loose thatch after slicing, leaving the soil layer as topdressing.

How Much Dethatching Costs

Lawn care professionals charge 175 per hour or 200 to 400 per 1,000 square feet to dethatch the lawn.

The cost to rent machines:

  • Simple, motorized dethatching machines can run from the low 100s to nearly 300.
  • Tow-behind dethatchers can vary widely, from about 70 to almost 3,000, depending on its size and features.
  • Nonmotorized options can run as low as 35 for a simple thatching rake. A gas-powered version can be rented starting around 50.
  • Slicing dethatchers come in a wide variety of options. One option is an attachment that fits on a regular walk-behind tiller, which runs about 80. Push, walk-behind, and tow-behind options can range from as low as 39 to more than 350.
  • Rental options are available for slicers, too, with in the ballpark of 110 per day.

DIY? Or Call in a Lawn Care Pro?

If slicing up that turf you’ve worked so hard on makes you more than a little nervous, it’s best to leave it in the hands of a professional lawn care service. In addition, the service has experience using the equipment, and has every piece that might be needed.

If you can handle a walk-behind lawn mower, you can handle a dethatching machine, Callahan says. And a dethatching machine is what is needed, he adds. Dethatching an entire lawn by hand is a “horrendous job and not effective,” Callahan says. If you are going to dethatch the lawn yourself, get a rake; you will need it for the clean up.


Despite popular belief, short clippings dropped on the lawn after mowing are not the cause of thatch buildup. Grass clippings are very high in water content and break down rapidly when returned to lawns after mowing, assuming lawns are mowed on a regular basis (not removing more than one-third of the leaf blade).

Dethatching removes the organic matter that impedes the flow of nutrients. Aeration removes cores of soil, something that relieves soil that has become compacted and gives roots space to grow. Aeration will remove small amounts of thatch.

Dethatching should not be done during periods of high temperatures, drought, or during late fall when winter is near. It’s best to dethatch at the beginning of the grass’s period of active growth.

A soil pH between 6.0 and 7.0 will favor microbial activity and breakdown of thatch.

Conclusion: A Call to Action

Don’t wait for your lawn to start losing its color or the grass to start dying to take action. Take a trowel and check how much thatch you have. If you have a thick layer of thatch, contact a local lawn care pro to take this destructive, but necessary, chore off your lawn care to-do list.

LawnStarter participates in the Amazon Services LLC Associates Program, an affiliate advertising program. LawnStarter may earn revenue from products promoted in this article.

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Main Image Credit: Agri-Fab, Inc. / Wikimedia Commons / CC0 1.0

Derek Lacey

Formerly the agriculture writer for the Hendersonville Times-News, Derek Lacey’s articles have appeared in U.S. News World Report, The Charlotte Observer, News Observer, and The State. He has won 15 awards from the North Carolina Press Association and GateHouse Media, for pieces ranging from news features and investigative reporting to photography and multimedia projects.

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Why, When and How to Dethatch Your Lawn

Not all lawns need dethatching, but when your lawn does need it, knowing how to dethatch your lawn is crucial to its future. Done properly, dethatching helps restore your lawn to health and keep it beautiful in years to come. By learning why, when and how to dethatch, you can keep your thick, lush grass on track. These lawn dethatching basics can help understand:

What is Thatch?

If you’ve ever seen a cross-section of soil and grass roots, you’ve seen the layer of organic debris known as thatch. A mix of dead and living plant material, thatch forms at the base of grass plants, where stems meet roots and soil. Some organic matter, such as small grass clippings or mulched leaves, break down quickly in healthy lawns, but other materials take much longer to decompose. When buildup outpaces breakdown, your lawn’s thatch layer grows thicker.

A thin thatch layer, less than 1/2-inch thick, is beneficial to lawn health.1 It acts as an organic mulch to help conserve soil moisture and protect against big fluctuations in soil temperatures. A thin thatch layer allows water, nutrients and air to penetrate into soil and reach waiting plant roots. But when thatch grows thick, grass suffers.

Thatch layers of 1 inch or more become barriers instead of benefits. Thick thatch blocks water and fertilizer, and grass roots get trapped in thatch, where they’re vulnerable to heat, drought and stress. Water from irrigation can accumulate in the thatch layer, too, so grass roots suffocate from lack of air. Thick thatch also provides a breeding ground for lawn disease and insect pests.

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Some lawn grasses are more prone to thatch buildup than other. Vigorous, spreading grasses such as Kentucky bluegrass, Bermudagrass and creeping fescues, may need regular dethatching. Clump-forming grasses, such as tall fescue or perennial ryegrass, seldom have thatch problems. Lawns with overly low soil pH or compacted soil are also prone to thatch. Overfertilization and heavy pesticide use contribute, too.

When to Dethatch Your Lawn

Always check your lawn’s thatch layer before dethatching. Take a garden trowel or spade and dig up a small wedge of your lawn grass and soil. You’ll be able to see and measure its thatch layer. If your thatch is 1–2 inches or more, you’ve probably already seen signs of poor grass color and weak, thin growth. Once you’ve confirmed your thatch exceeds the healthy mark, the time for dethatching has come.

Like most major lawn projects, such as planting new lawns or overseeding existing lawns, dethatching should coincide with peak growth times for your grass type. Active grass growth helps speed your lawn’s recovery.

Dethatch cool-season grasses, such as Kentucky bluegrass, in late summer or early fall. Dethatch warm-season grasses, such as Bermudagrass or Zoysia grass, after spring green-up, as they enter early summer’s peak growth. Never dethatch when your lawn is dormant or stressed; you can damage it beyond recovery.

Lawn aeration and dethatching are two different processes, but they can work together to help your lawn. Aeration removes cores of soil, including their thatch layer, and creates paths for water and nutrient to penetrate thatch and compacted soil. This helps prepare thatch for removal and speeds the breakdown of existing thatch. Dethatching helps slice through thatch into soil and remove the barrier of thick, accumulated organic matter.

How to Dethatch Your Lawn

If your thatch is over 2 inches thick, you may want to consider hiring a professional for the job. Excessive thatch can take more than one removal session, and removing too much at once can damage grass roots. Your local county extension agent can help you decide which route to take. If DIY is more your style, you can dethatch your lawn in three ways:

  • Manual dethatching rakes are heavy, short-tined rakes with curved blades designed to dig into your lawn and pull up thatch as you rake. Dethatching rakes are good for light thatch and general thatch maintenance on small lawn areas.
  • Power rakes are mower-like devices with rotating, rake-like tines that dig into thatch at the soil level and pull it up. Power rakes work well for lawns with thinner thatch layers and grass that can withstand intense raking.
  • Vertical mowers, also called verticutters, have vertical blades that slice down through the thatch layer and into soil, pulling thatch—and often grass roots—to the surface as they go. Verticutters are best for thick thatch layers on lawns in need of renovation. Blades adjust to control how much thatch you remove at once.

Most lawn and garden stores carry manual dethatching rakes. Equipment rental stores often keep power rakes and vertical mowers on hand, especial during dethatching season. Whatever option you choose, finish the job by raking up all the thatch debris and watering your dethatched lawn thoroughly.

What to Do After Dethatching

With dethatching done, it’s an ideal time to overseed your lawn and get it back on track for thick, lush, green beauty. By choosing premium grass seed such as water-conserving Pennington Smart Seed, you improve your lawn’s sustainability as you overcome thatch. For a quick, easy fix to thin grass, turn to Pennington Lawn Booster; this all-in-one product combines Smart Seed, professional-grade fertilizer and soil enhancers, all in a single, easy-to-use package.

To prevent future thatch problems, test your lawn soil every 3–4 years and follow soil test recommendations to keep soil pH and nutrients at optimal levels for thick, healthy grass growth. Your lawn may need lime to restore soil pH balance, which also promotes beneficial activity of thatch-reducing microorganisms.

Aerate heavy or compacted lawns annually and amend with gypsum to help loosen soil and encourage root growth. Fertilize your lawn, according to soil test recommendations, with the best lawn fertilizers to ensure it gets nitrogen it needs without over-fertilizing, and follow best practices for mowing and wise watering.

By learning why, when and how to dethatch your lawn properly and taking steps to prevent thatch, you can keep your lawn on track for healthy, thick, lush growth. Pennington is committed to providing you with the finest in grass seed and lawn care products so you can enjoy a beautiful, healthy lawn you’re proud to own.

Pennington with design and Smart Seed are trademarks of Pennington Seed, Inc. Sources:

P. Landschoot, Managing Thatch in Lawns, Pennsylvania State University Center for Turfgrass Science.