Should You Dethatch Your Lawn Every Spring?

By Brian Mounts | Mar 06, 2020
Should You Dethatch Your Lawn Every Spring

Deciding if you should dethatch your lawn every spring depends on several key factors.  What type of grass do you have? How thick is the thatch? Is there another time of year that your lawn would be better suited for dethatching?  And finally what type of equipment will you be dethatching with?

Dethatching is an excellent technique for every lawn in order to remain in pristine condition.  Dethatching helps deliver that rich and luscious green color that is sought after in turf grass.  It aids in reducing the number of insects and pests living in the grass and also will ensure that your irrigation during the dry summer months is actually reaching the roots below.

Removing the thatch, which is the upper most layer of organic matter that accumulates on the surface of a lawn can cause more harm than good.  Wait until it is at around ¾ inch thick before spending the time and energy to dethatch.

If I had to answer whether you should dethatch your lawn every spring (sight unseen) I would recommend that you do not dethatch at that time of year and certainly not every year.

What is Thatch & Why Do We Dethatch Anyway?

Thatch is that part of the turf that consists of old and dead roots. It is that layer that separates the turf from the soil surface.

Thatch build-up does not result due to grass clippings. In fact, grass clippings actually help to reduce thatch problems by decomposing rhizomes and old grassroots.

A thin layer of thatch (½ inches or less than that) isn’t harmful; in fact, it is advantageous for the plants. A healthy thatch range helps to prevent fluctuations in soil temperature. It also helps to make sure the soil doesn’t lose excess moisture.

Though, if this layer keeps building up over time, it might lead to a thatch problem. A thatch layer of 1″ or more might pose a threat to the health of your lawn. This is because, it might pose an issue in allowing nutrients, water, and air to penetrate into the soil.

We dethatch our turf grass lawns to provide the following benefits:

  1. Removes dead matter from the yard. This is often dead and matted grass, but can also be remnants from leaves and other yard debris.  This material begins to break down on the surface and acts as a mulch which can be good up to a certain point and then detrimental once it becomes too thick.
  2. By removing this layer of dead debris that is different shades of brown, you are left with only green grass. This results in that bright green color once the grass starts to regrow after the dethatching process.
  3. As the thatch thickens, it can become a serious moisture barrier. This will act as a very dry sponge during the driest summer months when you need to be irrigating the most.  When you water the lawn all of the water will get soaked up into the thatch and not reach the soil and the roots of the grass.  This means you end up having more dead grass or have to use up a lot more water than you otherwise would need.
  4. It can impede the exchange of oxygen from at the surface with the soil. In order to maintain a healthy lawn the soil needs to be able to breathe.  This is why people will aerate, but don’t get confused aerating a lawn is not the same as dethatching and they should not be done at the same time.

What Causes Thatch Buildup

Since dethatching can take its toll on your grasses, it’s best to prevent excessive thatch build-up. You’ll be surprised that what causes thatch to build upon your lawn isn’t anything external. Too much watering, overly mowing, and overly fertilizing your lawn can cause thatch to build up. Water enough, fertilize enough, and mow enough, but don’t go overboard. Too much of anything they say is never good.

Here is how I determine when to dethatch my own lawn and the advice I give clients requesting the service for their yards:

3 Signs Your Lawn Needs to be dethatched?

  1. Lawn is spongy and is difficult to push a lawn mower through the lawn.
  2. Color variations from green to brown are visible in the lawn.
  3. When you peel a layer of your lawn back the thatch is thicker than ½ inch

The Type of Grass Dictates When to dethatch

Cool Season Grass Dethatching

If your home is in a location with cool season grasses like Kentucky bluegrass then the late summer or early fall is the ideal time to dethatch.

Warm Season Grass Dethatching

If your turf grass is made up of warm season grasses such as Bermuda grass or Zoysia grass then plan your dethatching efforts after the spring green-up phase.  As these grasses enter in the early summer season which is when their growth is at their peak.

Plan to dethatch prior to best growing season for your grass. It is ideal if the grass will have at least a month and a half of peak growing season left after dethatching.

You never want to be dethatching when your lawn is dormant or stressed from the weather as it possible to damage it severely and take a year or more to recover.

Reasons for Not Dethatching in the spring:

  1. The biggest reason to not dethatch in the spring and certainly not in the early spring is that it tears up the turf when the grass is still dormant or just coming out of dormancy.
  2. It is very disruptive to the top layer of soil and will encourage the growth of weeds. If you have crabgrass issues the last thing you want to do is disturb the soil prior to its germination.
  3. Cool season grasses will be slow to grow into the distrubed areas leaving you with bare spots in your yard.

Reasons for Dethatching in the Spring:

  1. You will live in a climate with warm season grasses.
  2. Dethatching removes layer of dead material from last season right before the hottest driest months of the year, ensuring that your lawn irrigation will be as efficient as possible.
  3. The lawn has become so difficult to mow due to a very heavy thatch that the service is needed just so you can continue with regular lawn care.

How Often Should You Dethatch?

Thatch build-up varies with turf type, but even still, dethatching shouldn’t be a regular lawn care exercise. Unless it is absolutely necessary to, don’t dethatch often.

Thatch takes time to build up, and so dethatching every spring might be unnecessary and, worse still, harmful to your lawn. Because it is unlikely that if you do everything right, you’ll have excessive build-up in a period of one year.

Consider dethatching every couple years if you’re growing warm-season turfs and every 4-5 years if you’re growing cold season turfs but always look at your conditions first, you may not ever have to dethatch if the layer doesn’t ever get too thick.

Do not dethatch regularly, except when you see the need to. In doing this, your lawn will have enough time to recover, without risking the chances of being severely damaged beyond repairs.

3 Tools for Dethatching Your Yard

There are three preferred tools for dethatching your lawn in the spring or the fall.  Depending on the thickness of the thatch, the results you are seeking, and your budget will determine which tool you should use.

Manual Dethatching Rakes

A manual dethatching rake can be found online or at any nearby garden center.  They are a specialized rake specifically for removing the dead matter from turf grasses.  There are both fixed versions and one’s that can be adjusted to determine how aggressive the action will work in digging into the turf and pulling out the thatch.

To use a manual rake select the area that you want to work and simply push the rake back and forth over the year.  When you are pulling the rake towards you, the thatch is getting released and when you push the rake, back it is coming off the rake. Then using a regular rake you can pick up the debris and throw it away.

If you really need to break the rules around cool season grass and warm season grass dethatching then I suggest going with the manual dethatching rake as it is the least disruptive of the tools for this task.

Power Rakes

A power rake looks like a small lawn mower without the bag, but the underside is very different.  Instead of a large single rotating blade, it is a series of metal flails that rotate around so that they dig into the top layer of the soil.

Power rakes have a level setting similar to your lawn mower to set the height.  I always suggest starting high for your initial pass and then begin to lower the power rake so that it progressively is going deeper and deeper into the thatch.  The optimal setting for power raking will be removing almost all of the dead material and just starting to scratch the surface of the soil.

If the rake is digging into the soil more than just a little bit you will quickly notice deep scars and bare spots.  This is the #1 reason the vast  majority of homeowners are afraid of dethatching their own lawn.  It is very easy to cause severe damage with a power rake.

Eliminate that from happening by taking it slow and start with a high setting and work down.

Vertical Mowers

Vertical mowing also known as verticutting is very effective with very thick thatches as consist of solid mounted blades unlike the flail style in power rakes. They are designed to cut deep into the turf and effective at cutting lateral stems and rhizomes in the grass while dislodging the thatch.

Most homeowners looking to purchase a machine for dethatching will be best served with a power rake.

Things to Consider While Dethatching:

  • Ensure Your Lawn Is Moist Enough: The keyword being “moist” and not wet.
  • Watch Out For Weeds: Be careful not to dethatch if weeds are also germinating, you could have serious weed problems afterward.
  • Use Herbicides: You might want to make use of pre-emergent herbicides after the dethatching process.
  • Watch the Weather: Detaching can be a stressful activity for your lawn. You don’t want to contribute to this. Try to dethatch the lawn on a day when the weather is cool.
  • Mow Your Lawn: Finally, never attempt detaching an overgrown lawn that might cause too much strain for the turfs. Before you begin, make sure you mow your lawn to at least half its regular height.

What to Do After Dethatching

For optimum results, these are basic practices you should carry out after dethatching:

#1. Overseeding

This is something you want to consider after dethatching. It will definitely help in restoring your lawn to its natural, verdant, and lush look.

#2. Test Your Lawn Regularly

To prevent further thatch complications, it’s advisable to test your soil at least every 3 – 4 years. Also, make sure to follow soil test specifications in order to keep the soil nutrients, and pH level at its optimum. Doing this will help in reducing thatch build-up.

#3. Fertilize, Water and Mow Wisely

Make sure to fertilize your lawn based on the recommendation of the soil test. Just don’t over-fertilize, as this can bring you back to square one.

Same with watering and mowing the lawn. You’ll need to do it right to promote growth and prevent thatch problems. Water enough, but don’t over-water the lawn!

#4. Aerate

Aerate! Aerate! Aerate! I can almost not overemphasize this. It’s important to aerate compacted fields, this will help in loosening the soil and foster the growth of the turf root.

Dethatching is great for your lawn and should be part of your lawn care routine every few years or so.

All said make sure you inspect your lawn’s thatch thickness on an annual basis. If it is thicker than ½ – ¾ of an inch, let whether you have a cool season turf or warm season turf dictate if you should dethatch your lawn in the spring or fall.

More answers on how to grow green grass.