You have probably already heard of thatch and know that dethatching is a best practice for lawn care and a healthy lawn. But where does thatch actually come from, and what is it? Well, it’s part of a process that naturally occurs, giving the soil fertility and making it suitable for growing plants, including your lawn. So, what causes thatch in lawns? Let’s take a look.
What Causes Thatch in Lawns? (The Short Answer)
Many different elements make up lawn thatch, like dead grass blades, grass clippings created by your lawn mower, and any other organic material that finds its way onto your lawn, such as leaves from trees and shrubs. Once this organic material begins to decompose, it turns into thatch.
Lawn Thatch Causes (A Closer Look)
To understand what causes thatch in a lawn, you first need to know where the material comes from. Here are four lawn thatch causes you’ll find adding organic material to your lawn. Let’s take a closer look.
- Natural Material From Grass
- Grass Clippings
- Dormant Grass Remains
- Additional Vegetation
Natural Material From Grass
As the grass grows new blades, the lower blades of the plant begin to die. These dead grass blades slowly decompose and fall onto the soil bed. This process of releasing old blades allows the grass to grow taller and stronger as it no longer has to waste energy maintaining old blades that don’t benefit the plant.
As these dead grass blades decompose on top of the soil, they begin the process of thatch buildup by creating the top layer of the earth called the organic horizon.
The bulk of the thatch layer comes from the grass clippings created by mowing. Every time you mow and mulch your clippings, you add organic material to the thatch layer. So, the volume of grass clippings left to decompose into the lawn during the cutting season makes up a large section of the layer of thatch.
Dormant Grass Remains
Depending on your lawn’s grass type and your location, you might experience a complete browning of your lawn during the cold winter months and the summer heat. Unless you remove the dead grass, it will all become part of the thatch. With some grass types, the entire lawn may go brown at once, adding a huge amount of material to the thatch in one go.
I use my lawn mower to mulch up various things around my yard throughout the year. For example, I mulch things like dead leaves from bushes and trees and even trimmings from my bushes and plants. If you have mulching blades on your lawn mower, you’re likely able to mulch most things down to pretty much nothing. Mulching blades are a great time saver, but all of this material is being added to the thatch and contributing to potential problems further down the line.
Prevent Thatch Buildup (I’ve Had Some OK Results)
There are a few different methods you can use to prevent thatch buildup or at least slow it down. Now that you have a good understanding of what causes thatch buildup in lawns, you can use this knowledge to reverse or slow down these causes. Here are five methods you can try.
- Bag & Collect Clippings
- Limit How Much You Mulch
- Pick Up Leaves
- Be Careful What You Mulch
- Power Rake Your Lawn
Bagging & Collecting Clippings
You don’t want to completely eliminate the organic layer of your soil makeup. Instead, you want to keep it at a beneficial thickness. The best place to start is by limiting the amount of new material that reaches the organic layer. In my experience, the biggest contributor to thatch is grass clippings from mowing. Therefore, if your lawn mower has a bagging option to collect clippings, this is a good place to start.
However, I understand that bagging systems don’t always come as part of larger lawn mower setups like tractor mowers and zero-turns. So, you guys with larger mowing equipment will have to focus on the following methods.
Limit How Much You Mulch
If you are using a lawn mower with a bagging system, then you’ll want to make sure that you make a point of actually using it. In the past, I always removed my bag from my lawn mower and mulched the clippings instead. I opted for mulching for two main reasons.
One, mulching is easier than emptying a bag of clippings every few passes. Two, you get some nutrients from the clippings as they decompose. But I changed up my method when I realized that alternating between mulching and bagging actually makes a big difference to the amount of thatch buildup on my lawn.
So, if you have the ability to limit how much or often you mulch, you’ll be able to greatly reduce the amount of material added to your lawn’s thatch.
Be Careful What You Mulch
My next method to reduce what causes thatch in lawns is to be careful what you are actually mulching. I’ve noticed that certain leaves, such as sea grape leaves, mahogany leaves, and even the leaves from my live oak trees, can take a long time to decompose. But it’s mainly the seagrapes that are a problem, as they can take months to finally disappear.
So, before you start mulching all of the organic material on your lawn, double-check that the material won’t take a long time to decompose and thicken up your layer of thatch.
Power Rake Your Lawn
If you find yourself with a lawn mower that isn’t able to collect clippings, you’ll want to try a different method. While you could grab a spring rake and rake up the grass clipping, this is a long and slow process, not to mention a backbreaking job. Instead, you can try using a power rake.
By now, you know that decomposing organic material is what causes thatch buildup in a lawn. But this happens in stages. The very top layer of material that sits on top of the thatch doesn’t actually become part of the thatch until it begins to decompose. This process happens as more material gets layered on top, causing the older material to move further down, deteriorate, and become thatch.
So, you can use a power rake to rake out the top layer of material before it becomes part of the thatch. All you have to do is push the power rake over your lawn the same way you would use a push lawn mower and then collect the waste.