Posted by Cause my lawn has thatch – The term “thatch” refers to a buildup of dead and living grass stems, roots, and shoots that sit directly on top of the soil, right below the grass.
In warm, humid conditions thatch will decompose quickly and serve as a useful source of nourishment for the soil.
However, if it’s not breaking down as quickly as it’s forming, the thatch will accumulate and start to cause problems.
If the thatch is less than 1/2“ thick, you should leave it to work its magic. If you notice that the sheet of organic matter is getting thicker over time.
You’ll need to take some action to prevent it from weakening your lawn and providing a haven for pests and diseases.
When you have a thick layer of thatch that prevents moisture and fertilizers from filtering down to the roots.
And you can find yourself adding too much water and fertilizer, both of which can damage the lawn.
In severe cases, the grassroots can start to grow in the thatch instead of in the soil.
Thatch forms easily when:
- The soil is wet and heavy; when it’s alkaline (pH is high); or when it’s compacted
- You’ve applied so much pesticide that earthworms and microorganisms can’t do their jobs
- The lawn has received too much fertilizer, and is growing faster than the waste matter it generates is able to decompose
- It’s warm and you have creeping grass species such as Bluegrass, Bentgrass, Bermuda, or Zoysia
It’s important to note that you don’t get more thatch buildup when you mulch your lawn clippings.
Since grass clippings are 85% water, they decompose quickly and actually add nitrogen to the soil when you leave them on the lawn.
This reduces the need to use fertilizers.
Keeping thatch under control
So, if you have more than ½” of thatch, how do you get rid of it and/or improve the condition of your lawn so that it won’t reappear?
Dethatching
Maybe you’ll get away with just raking the turf energetically, or you might have to resort to using specialist power tools.
You can either engage a lawn care service to do the job or rent a machine at a tool rental store or garden center.
A vertical mowing dethatcher has spinning vertical blades that pull the thatch up to the surface and cut it.
A power rake dethatcher rips up the thatch with the help of sturdy, spring-loaded metal wires.
Whichever method you pick, your lawn will be a mess, so you’ll need to clear away the loosened vegetation and use it for compost.
After you’ve removed the thatch, your turf will be weak.
You can shorten the recovery time by giving it some fertilizer, overseeding it if required, and then watering it.
Topdressing
To promote increased microbe activity in the soil and the breakdown of thatch, try topdressing with humus that has a high organic content. You can also water with an organic “tea”.
This is not a quick fix, though, and won’t be sufficient to restore your lawn if the thatch situation has already gotten out of hand.
Core aeration
Use a special tool with hollow tines to punch holes in the lawn so that water and air reach the soil more easily.
The organic matter removed disintegrates and serves as a top dressing, which helps get rid of thatch.