Should I Aerate or Dethatch My Lawn First? [When + Overseeding]

Both aerating and dethatching are important practices when it comes to proper lawn care. It helps with root penetration and easy flow of air, water, and nutrients in the core for better root growth. So, should you aerate or dethatch?

If your soil is healthy with enough microbial activity, you may only need to dethatch once a season and probably aerate once or twice a year depending on the type of soil you have.

If you’re growing grass in sandy soil, you’ll need to aerate just once per season, but if it is clay soil, twice a season may be the best option for you.

Should I aerate or dethatch first?

It is best to dethatch first before aerating your lawn. This way, you’ll remove the excess debris and promote healthy root development. Aerating is best done when there’s the problem of compaction. Both dethatching and aerating your lawn will improve air, nutrient, and water penetration into the root zone of your grass.

  • Thatch is the main problem these two processes address. It occurs when your turf accumulates too much dead organic matter than can be broken down.
  • It starts as a shallow layer of debris that makes your lawn feel spongy. If your lawn does not have enough microbial activity to break down the organic matter, thatch buildup occurs.
  • Soon enough, your lawn will start suffering from thinning and slow growth due to poor water, air, and nutrient penetration through the thick core of thatch.

However, if the amount of thatch is low you can just remove it using a dethatching tool or a power rake.

Dethatcher vs Aerator

A dethatcher vs aerator, which one does a great job? The two tools may have closely related functions, but in general, they almost go hand-in-hand. Here are a few differences to help you decide which one to use:

DethatcherAerator
A dethatcher works by removing the top-most layer of dead grass to allow the soil to breathe.A lawn aerator works by creating small holes into the soil to relieve soil compaction.
Dethatching loosens topsoil in preparation for overseeding.You do not necessarily need to aerate before overseeding.
A dethatcher works well when you have a lot of dead grass on top of the soil, making the lawn feel spongy.An aerator is best used when the core has a thick layer of thatch, usually more than 0.5 inches.
RECOMMENDED DETHATCHER
Sun Joe AJ801E 13 in. 12 Amp Electric Scarifier + Lawn Dethatcher...
RECOMMENDED AERATOR
Rolling Lawn Aerator 18-inch Garden Yard Rotary Push Tine Heavy...
Sun Joe AJ801E 13 in. 12 Amp Electric Scarifier + Lawn Dethatcher...
Rolling Lawn Aerator 18-inch Garden Yard Rotary Push Tine Heavy...
RECOMMENDED DETHATCHER
Sun Joe AJ801E 13 in. 12 Amp Electric Scarifier + Lawn Dethatcher...
Sun Joe AJ801E 13 in. 12 Amp Electric Scarifier + Lawn Dethatcher...
RECOMMENDED AERATOR
Rolling Lawn Aerator 18-inch Garden Yard Rotary Push Tine Heavy...
Rolling Lawn Aerator 18-inch Garden Yard Rotary Push Tine Heavy...

Affiliate links and images pulled from the Amazon Product Advertising API on: 2021-07-29

Use both to maintain a perfect lawn year round, year after year. Both should last you many, many years.

You can decide to dethatch and aerate at the same time especially if it is in the spring and you have lawn debris and compaction problems. It will help with establishing a better lawn for the season ahead.

Some lawn machines come as a dethatcher and aerator combo, and can really come in handy for doing the two tasks at the same time.

Differences between power raking and Lawn Aeration. What is power raking? What is lawn aeration?

How much thatch is too much?

About half an inch of thatch on your turf is beneficial because it contains microorganisms that break down organic matter into nutrients for your grass.

However, when it is more than 0.5 inches, the core becomes too tough for water to penetrate and your turf will easily develop what is called shallow root syndrome.

This is when you’ll notice roots starting to coil up and growing closer to the surface where there’s easy access to water instead of growing deeper into the soil.

A lawn with a thick layer of thatch becomes less tolerant to drought, prone to turf diseases, and will grow thin easily due to inadequate supply of nutrients for healthy growth.

Here are more problems with thick thatch:

  • Poor fertilizer penetration into the soil which means poor feeding of grass.
  • Pesticides such as grub control may not penetrate deep enough to be effective in getting rid of the pests.
  • Grass fungus becomes common due to the accumulation of harmful fungi feeding on the debris.

The major reason for the slow decomposition of dead grass and debris on your lawn is usually too much use of chemicals for lawn care such as chemical weed killers or synthetic fertilizers.

Lawn Aeration

lawn aeration steps
Stages lawn aeration. Before and after steps.

Aeration is the process of creating small holes in the lawn while pulling thatch plugs out of the soil. It helps solve soil compaction and allows the lawn to breathe better.

Aeration is done using a lawn aerator – a machine with special tines that plug the soil to relieve compaction. Aeration tines should be sharp and go deep enough to pull out the thatch plugs out of the core.

If you’re used to leveling your yard using a lawn roller, you can easily create a soil compaction problem. I would recommend that you aerate the lawn almost immediately after running the roller over the yard.

My Recommended Aerator

  • For smaller yards

You can hand push this aerator around pretty easily, even on clay soil (water first to make it easier). Typically this unit is around $50 and worth it so that you can aerate whenever you need to.

Rolling Lawn Aerator 18-inch Garden Yard Rotary Push Tine Heavy...
458 Reviews
Rolling Lawn Aerator 18-inch Garden Yard Rotary Push Tine Heavy...
  • 🌿Easy to use-- Goplus lawn aerator makes it extremely easy to aerate soil yourselves for a way greener, healthier and more beautiful lawn. Simply rolling the aerator and loosen the soil.
  • 🌿Durable Steel Material-- Our aerator is made of durable steel, smooth and stable. Rolling parts in both sides are made of plastic, flexible and decrease the whole weight when working.
  • 🌿Deep Watering for Lawns-- Ideal for use with looser soils higher in sand concentrations, allowing deep watering for lawns.

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  • For larger yards or for easier coring

Check out the Step N’ Tilt

Step 'N Tilt Core Lawn Aerator Version 3 (with Container)
168 Reviews
Step 'N Tilt Core Lawn Aerator Version 3 (with Container)
  • Faster and easier to use than other manual aerators. Simply step and tilt. This patented lawn aerator (U.S. Patent No. 8,714,275 and other patents pending) makes core aeration easy and enjoyable for do-it-yourselfers (DIYers) and professional landscapers. New and improved clog-resistant tines. Case-hardened for extra durability. The tines may be sharpened or replaced when worn.
  • For use in areas with grass only; tines will clog if used in bare soil. All core lawn aerators require that the soil be VERY moist. This Step 'N Tilt is no exception. Please aerate one day after at least one inch of rain or irrigation. If you have a sprinkler system, each sprinkler zone will need to run for 60-90 minutes. In other words, the soil must be very moist. Question: Why must I wait one day? Answer: Because it takes time for water to be absorbed into the soil, particularly clay soil.
  • Designed for operators between 4-feet and 6-feet 5-inches tall. Recommended minimum operator weight to use one set and two sets of tines are 80lbs and 150lbs, respectively. Recommended for aerating small yards or areas not accessible by motorized lawn aerators. It can be used to aerate large yards but will require significantly longer time and effort than a motorized lawn aerator.

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When and how often to aerate your lawn

This depends on your type of soil. If your lawn is growing on sandy soil, you’ll only need to aerate it once a year during springtime. If you have clay soil, you can aerate your lawn 2-3 times per year.

Aerate during fall to give the thatch plugs enough time to decompose over the winter period, leaving behind all the nutrients for better growth come spring.

You can also aerate the ground just before your lawn soil temperature reaches 55 F in the spring. This will make it easier to put down a good weed pre-emergent to help control weeds such as crabgrass in your lawn.

Lawn Dethatching

Thatch is a layer of living and dead grass shoots, roots, and stems that forms between the green grass blades and the soil surface. It is actually beneficial to your lawn, but when it becomes too much, it becomes a major barrier between the atmosphere and the soil in your lawn.

A thick layer of thatch (more than 0.5-inch) prevents penetration of lawn food, especially liquid fertilizers, and even air from reaching the roots of your grass.

To fix this, you need to dethatch in preparation for overseeding or even aerating your lawn.

Dethatching to remove excess debris or dead grass helps your lawn in a few ways:

  • It allows proper contact between fertilizer and the soil for proper lawn feeding.
  • Dethatching makes sure new grass seed gets in contact with the soil when overseeding the lawn.
  • It allows for better oxygen transfer, making your lawn breathe better for the healthy growth of grass.
  • Makes the grass appear deeply green. Too much dead grass will quickly start to appear as though brown patches are forming in your lawn.

My Recommended Dethatcher

I really like the Sun Joe Electric Lawn Dethatcher, super easy to use on small to medium yards.

Sun Joe AJ801E 13 in. 12 Amp Electric Scarifier + Lawn Dethatcher...
8,365 Reviews
Sun Joe AJ801E 13 in. 12 Amp Electric Scarifier + Lawn Dethatcher...
  • Powerful: 12-amp motor rakes a 13" Wide path to get your job done faster
  • Adjustable deck: tailor raking depth with 5-position depth control
  • Scarified: use the Scarified function to cut grass roots for thicker growth, healthier lawns

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Anything over .3 of an acre I would recommend a pull behind dethatcher. Such as the Brinly Toe Behind.

Brinly DT-48BH Tow Behind Dethatcher, 48-Inch
496 Reviews
Brinly DT-48BH Tow Behind Dethatcher, 48-Inch
  • Maximum Thatch Removal: For larger mowers and lawns, a 48" working width and 2 rows of 12 independently flexing spring steel tines comb through a lawn, lifting thatch up and out of the lawn where it can be mowed or mulched to promote a healthier root system.
  • Ideal for Large Yards: Wide 48" working width is perfect for larger mowers or bigger greenspaces - covering more ground for quicker results.
  • Long-Lasting Construction: All steel construction, tines are made of durable spring steel; in the unlikely event of a breakage, a safety rod is included to catch the tine and prevent contact with mower blades. No flat rubber-tread transport wheels for durability.

Affiliate links and images pulled from the Amazon Product Advertising API on: 2021-07-28

A very important part of dethatching or power raking your lawn is cleaning up the debris. When aerating, you leave the thatch plugs on your lawn while you will need to remove the debris of dead grass from your lawn when dethatching.

Is it better to dethatch or aerate?

Dethatching and aerating seem to do the same thing, but there’s time for each. So should you dethatch or aerate? Core aerating not only breaks up thatch buildup but also relieves compacted soil.

Dethatching mostly loosens the top layer of soil and also removes the layer of debris (dead grass) from the soil. Dethatching can really help when overseeding your lawn.

Dethatch or aerate before overseeding?

Both aerating and dethatching are recommended before overseeding because they improve grass-to-soil contact for proper germination. In most cases, you’ll only need to dethatch to remove the debris that is covering the soil and preventing grass seed from germinating properly.

However, if you have compacted soil in your lawn, you may want to aerate the core to allow deeper penetration of water into the soil. Deeply and well-watered soil promotes healthy and deeper root development of the new grass seed.

After overseeding, topdress the area with about 1 yard of compost per 1000 square feet to increase the rate of grass seed germination in your lawn.

Does a Dethatcher aerate?

Most dethatchers are simple tools such as lawn rake. Depending on the type, you can use it to dethatch your lawn if it is not heavily compacted.

However, using a mechanical aerator often produces better results compared to a dethatcher or a rake.

8 thoughts on “Should I Aerate or Dethatch My Lawn First? [When + Overseeding]”

    • I’ve had st Augustine for 10 years now and never had to dethatch. I can see if parts start to die off then u want to remove and replace.

      Reply
  1. I purchased a sunjoe Scarifier/Dethacher. I might not have needed to use the Scarifier but I did get rid of a ton of dead grass and thatch.

    Should I wait a few days before aerating and overseeding?

    Thanks

    Reply
    • Hi Matt, thanks for the comment and sorry for the delay in replying. I’m assuming you waited a few days before aerating. I would say that you don’t really need to wait after dethatching.

      Reply
  2. Great article. for aerating in the fall, how late is too late for aerating? And … I would assume to aerate after the short mow so I’m not sucking up plugs and nutrients.

    I’m in NE WI, avg temperatures going into November are 30s-40s overnite, 40s to 50s during the day (in the forecast), just coming through a cold spell of highs in the 40s.

    Thank you, Mike

    Reply
    • I would say its probably too late in the season for you now to aerate but you can probably still get it in. Don’t mow too short though.

      Reply
    • You should scarify before overseeding for sure. Do it right away so that the ruts you have created during scarifying the soil don’t fill back in. You want the seeds to sit nicely in the ruts and then you can lightly cover over. For seeding make sure you are keeping the ground moist for at least 14 days for proper germination and growth.

      Reply

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