20+ things to know about Lawn dethatching

Have you noticed your lawn looking lackluster and thin, despite your best efforts to maintain it? If so, the culprit may be excessive thatch buildup. In this article, we’ll explore what lawn dethatching is, when it’s necessary, and how to do it correctly to restore your lawn to its full potential.

What is dethatching

Dethatching is the process of removing the layer of dead grass and other organic material that accumulates between the soil and the living grass blades. Too much thatch can create a barrier that blocks water, air, and nutrients from reaching the roots of the grass, leading to an unhealthy lawn.

Thatch is not grass clippings

Thatch is composed mainly of grass stems, roots, rhizomes, and stolons. Other organic matter such as dead leaves and grass clippings play a smaller role because they decompose relatively quick. Stems are typically more difficult to decompose than grass blades due to their higher lignin content. Lignin is a complex organic compound that provides structural support to plants, but this means it is more difficult to break down. Stems may also have a thicker cuticle layer than grass blades, which can slow microbial decomposition.
Don’t worry about leaving clippings on Lawn
Overall, the combination of higher lignin and thicker cuticle in stems makes them more resistant to decomposition than grass blades. Rest assured, leaving grass clippings on the lawn will not exacerbate a thatch issue.

Is all thatch bad?

Some thatch is actually beneficial for a lawn, as it can provide insulation and protection for the roots. A thin layer of up to 1/2 inch is considered normal and healthy. Thatch doesn’t really start to be a problem until at least 3/4 to 1 inch. If your thatch is between 1/2 and 3/4 inches, don’t panic, you can adopt strategies to reduce thatch without machines.  See below.

How to tell if you need to dethatch

Most home lawns do not require dethatching. If you suspect a thatch problem, you must take a soil core sample and measure the thickness of the thatch layer. If the thatch layer is more than 3/4 inch thick, your lawn may be suffering.

How to dethatch properly

Aeration is the best method that can reduce thatch buildup in a hurry. By creating small holes in the soil, water, air, and nutrients will encourage thatch decomposition.

Is dethatching expensive?

The cost of dethatching can vary depending on the size of your lawn and the method you choose. DIY options such as renting a dethatching machine can be less expensive than hiring a professional service. Dethatching is straightforward, if you can handle a lawn mower, you can dethatch too.

When to dethatch

The best time to dethatch is when the grass is actively growing, typically in the spring or early fall. Avoid dethatching during periods of drought or extreme heat.
The reason for this is to quickly recover the damage done by dethatch blades. Dethatching is not beneficial to healthy grass in any way, it serves to remove debris at the expense of the growing lawn. In some cases it is justified.

Dethatch before seeding

It is always recommended to achieve good seed-to-soil contact to improve germination rates. If you plan on dethatching, take advantage of the opportunity by overseeding afterward. Dethatching will increase the chances of seeds reaching the soil through the thatch layer.

What type of dethatcher is best

Dethatching blades come in two types: flail and spring tine. Flail blades are aggressive to remove deep thatch but significantly damage the living grass blades and stolons. Spring-tine blades are gentler and better suited for light raking but still damage the grass.

What to do with thatch clippings

grass clippings
Remove heavy clippings after dethatching to prevent them from causing further thatch buildup. Alternatively, If you have a high-powered mulching mower, and only a little thatch, you can mulch thatch back into the lawn.

What’s the cause of thatch problems?

Excessive thatch is caused by compounding factors, including over-fertilization, overwatering, mowing too low, and soil compaction. Certain cool-season lawn grasses, such as Kentucky bluegrass, produce more thatch than others. In other words, thatch problems are a result of bad lawn management.

How often should you dethatch the lawn?

Dethatching is “generally recommended every 2-3 years for most lawns”. The problem is this recommendation doesn’t include a diagnosis. Dethatch only when needed to save money and save time.

Dethatching to remove rocks

While dethatching can remove some small debris, it is not designed to remove large rocks. Rocks can damage the blades of the dethatcher leading to costly repairs. It’s important to clear any large rocks before dethatching to avoid damage while dethatching.

Liquid dethatching

Liquid dethatching products are available that claim to help break down thatch and promote healthy soil. Their effectiveness may vary but they most likely do nothing at all. It is true that microbes break down thatch but these products are unregulated and can’t promise product viability.
For example, biological control products are registered, tested, and patented strains of specific microbes. Liquid dethatch products are not.  Garden myths have a great article on this.

How to prevent thatch buildup

Balanced fertilization
A well-fertilized lawn promotes healthy grass growth and can reduce thatch buildup. Nitrogen (N) is an essential nutrient for grass and is often the limiting factor for growth. However, excessive N application can lead to thatch buildup, as it stimulates above-ground stem production.
Annual composting
Compost can enhance soil quality and reduce thatch buildup in lawns. Compost is decomposing organic matter, that contains nutrients, and improves aerification and water-holding capacity for nutrient cycling. All things needed to break down thatch. Compost is an effective thatch buster.
Proper watering
Watering practices also play a role in preventing thatch buildup in lawns. Overwatering can lead to shallow root growth and low oxygen levels that contribute to thatch buildup. Underwatering can reduce microbial activity in the soil, making it harder to decompose thatch.

Dethatching to control creeping charlie

Creeping charlie is a common lawn weed that is difficult to control in Ontario. Dethatching can help remove some of the above-ground runners of the weed, but it may not completely eliminate the problem. It is a good idea to dress and seed the areas after dethatching or raking creeping charlie.

Thatch and insect problems

A thick layer of thatch can make it difficult for live microbes to penetrate to the soil and reach the grubs or chinch larvae. It’s important to thoroughly water in microbial insecticides for this reason.

Your neighbor’s dethatching recommendations

Some people may recommend dethatching because it’s a satisfying process with immediately visible results. Often, homeowners that recommend dethatching take good care of their lawn backing up their claim. If you’re unsure, It’s best to let a professional advise you on whether you need to dethatch your lawn.

Dethatching vs. power sweeping

Dethatching and power sweeping are two different processes with different goals. Dethatching is intended to remove thatch from the surface of the soil. Power sweeping, on the other hand, is designed to remove debris like leaves, twigs, and other small objects from the surface of the grass. If debris is the primary concern, power sweeping may be more appropriate. Power sweeping is less destructive to the lawn and may be a better option depending on your goals.

Importance of maintaining healthy thatch

A healthy thatch layer can provide several benefits to a lawn, including insulation, moisture retention, and erosion control.
  • Moisture retention: Thatch can act as a sponge, absorbing and retaining water from rainfall or irrigation. This can help to reduce soil erosion and improve water availability for grass roots, especially in sandy soils.
  • Temperature regulation: Thatch can insulate the soil and protect grass roots from extreme temperatures, both hot and cold. This can help to maintain optimal soil and air temperatures for healthy grass growth.
  • Nutrient recycling: Thatch contains nutrients such as nitrogen, phosphorus, and potassium that can be released back into the soil as it decomposes. This can help to reduce fertilizer needs and improve soil fertility over time.
  • Soil protection: Thatch can help to reduce soil compaction and erosion, as it provides a cushioning effect for foot traffic and other impacts. This can help to maintain soil health and structure.
  • Microbial habitat: Thatch can provide a habitat for beneficial microorganisms, such as bacteria and fungi, that help to decompose organic matter and enhance nutrient cycling in the soil. This can help to maintain a healthy soil ecosystem and support plant growth.

Spring dethatching for snow mold

Snow mold is a common fungal disease that can occur in lawns that are covered by melting snow for extended periods of time. Dethatching can help prevent snow mold by removing excess thatch that’s trapping moisture and creating the ideal environment for fungal growth.
Redistributing snow and using a leaf blower to fluff the lawn in spring can prevent snow mold. This way, you can avoid lawn damage caused by a dethatcher.

Wrapping up

A healthy thatch layer in lawns has benefits like retaining moisture, regulating temperature, recycling nutrients, and protecting the soil. But too much thatch can cause problems like shallow roots, less nutrient uptake, and vulnerability to pests and diseases.
To address thatch buildup, dethatching can be useful. However, it’s important to core test the lawn before dethatching to avoid unnecessary damage.

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