Eliminating thatch is crucial for keeping your lawn in optimal condition, yet it’s frequently overlooked. This process can be performed by hand or using machinery, aiding in the preservation of a robust and vigorous growth habitat for your turfgrass.

Your lawn should be dethatched every 2 – 3 years, or when the thatch layer exceeds ½ inch in thickness. Some lawn varieties need dethatching more than others as they are thicker and more prone to holding a thicker thatch layer.

To check if your lawn is due for dethatching, poke a finger into the grass, and push down to note the depth of the thatch layer. You can measure the thatch thickness by removing a wedge of your lawn with a sharp garden tool and placing a ruler against the profile to determine the thatch thickness.

When should I dethatch my lawn?

When should I dethatch my lawn

Lawn dethatching must be performed only when weather and growing conditions favor a rapid grass recovery. It is ideal to have several weeks of active growing after dethatching to ensure a lush and uniform growing grass.

For cool-season lawns, plan to dethatch in early fall, between late September and mid-October. Kentucky bluegrass and fescue experience periods of vigorous growth during this period. Cool-season grass rarely produces thick thatch, and it is prudent to dethatch with restraint so they have a better chance of recovery.

If you have a warm-season lawn, then it’s best to dethatch in spring. Preferably the months of February and March before greening. Lawns having cultivars of Bermuda grass and zoysia tend to produce large quantities of thatch. And they’ll require extensive dethatching every spring using a vertical mower, followed by deep raking to remove thatch.

However, spring dethatching also increases the emergence of invasive crabgrass. It may be necessary to apply preemergence herbicides if your lawn is susceptible to crabgrass. Remember to use pre-emergent weed treatments after you dethatch your yard – not before.

Why is thatch bad for a lawn?

The presence of thatch in moderate proportions promotes lawn growth. However, too much thatch provides the perfect breeding grounds for fungi and insect pests. The destructive effects of a thick layer of thatch results in a weakened lawn and directly contributes to the premature death of turfgrass.

Excess thatch can hurt your lawn in so many ways. Here are a few examples:

  1. Excess thatch traps grassroots within the thatch layer, resulting in shallow root development, which leaves your lawn defenseless against drought and extreme temperatures.
  2. An overabundance of thatch encourages insect activity and disease by restricting the soil intake of oxygen, water, fertilizer, and pest control treatments.
  3. A thick layer of thatch retains water and encourages high humidity, which fosters disease.
  4. A thick layer of thatch can result in scalping.

Remember, once thatch is established, it quickly creates conditions that promote its growth. To prevent this, lawn owners must adopt preventive thatch control practices. Dethatching your grass is worth it, as it can help to remove the thatch layer and improve the health of your lawn.

Why is thatch bad for a lawn

What's the difference between dethatching and aeration?

Dethatching and aeration are two very different lawn care techniques that work differently to achieve similar outcomes.

Although, most lawn owners misconstrue both methods and their benefits. Their dissimilarities are quite distinct, and in this section, we’ll examine critical aspects of each procedure so you’ll not only be able to recognize the differences but also you’ll have enough knowledge to discern when your lawn needs dethatching or aeration.


Dethatching is the process of removing the excess thatch layer consisting of dead plant stems, decomposing organic material, and debris from your lawn.

What dethatching does

  1. Dethatching increases your lawn resistance to drought and disease.
  2. Dethatching improves soil drainage and reduces water pooling.
  3. Dethatching exposes the soil to more sunlight and reduces your lawn humidity.
  4. Dethatching erases the threat of insects and pests to your lawn.

Signs that you need to detach your lawn.

  1. When the layer of thatch on your lawn is more than ½ inch.
  2. When you notice your lawn retaining large amounts of water, which forms puddles on your turf.
  3. If your fingers can’t penetrate through the thatch to touch the soil.
  4. When your lawn feels bouncy and or springy when you’re walking on it.


Aeration loosens the soil by removing soil and turf plugs from your lawn, allowing air, water, and nutrients to penetrate deep into the root zone.

What aeration does

  1. Aeration encourages the activities of microbial organisms that break down lawn thatch.
  2. Aeration promotes the circulation of air within the soil.
  3. Aeration removes thatch without stressing the turfgrass.
  4. Aeration promotes root development by increasing air, water, and nutrients to the root zone.

Signs your that your lawn needs aeration.

  1. Your lawn develops thinning and bare patches.
  2. Your lawns stop growing even after you’ve overseeded and fertilized.
  3. Your lawn grass suddenly looks worn, discolored, and dull.
  4. Your lawn loses the ability to retain moisture.

Tips on how to dethatch your lawn

Below is a list of helpful tips to help you dethatch your lawn successfully.

  • Moist lawns provide the best conditions for dethatching. Wet your lawn intermittently for a couple of days before you detach. Do not attempt to dethatch a wet or a parched lawn.
  • Request that the cutting depth and spacing of the vertical mower’s revolving blades be set to your lawn thatch thickness by the rental equipment company.
  • Mark sprinkler heads, irrigation lines, and all objects embedded in your lawn before dethatching with the power dethatcher.
  • Make several right-angled passes across your lawn with a power dethatcher. Do not leave any space between the grass. It’s best to overlap by a couple of inches to ensure you cover as much ground as possible
  • After going over the entire lawn, rake and remove all the dethatched debris, heap the thatch debris in a compost pile to recycle back into your yard, or use it as mulch.
  • Fertilize your lawn after dethatching to help your grass recover quickly. Do not fertilize before dethatching.
  • Apply pre-emergent herbicide after dethatching to prevent weeds from taking over your lawn before your grass fully recovers. Do not use pre-emergent herbicides if you wish to reseed.
Benjamin McInerny
Author: Benjamin McInerny - is a qualified arborist and a DIY Home Improvement enthusiast. Ben has a extensive experience on renovation projects including, mold removal, painting, fence installation and more. Ben shares his skills with DIY and gardening enthusiasts.