Thatch is a spongy layer of plant debris that accumulates below the leaves in warm-season lawns. It builds up in Bermuda, Zoysia, and Centipede lawns because they grow by “runners” (technically called stolons and rhizomes). The thatch layer consists of living and dead material, both produced by the lawn itself.
Dethatching is the process of removing thatch by mechanical means. It’s not always necessary to dethatch a lawn; some thatch is to be expected and about 1/2 inch of buildup is typical.
If the thatch layer is more than 1/2 inch, your lawn will show signs of struggling due to heavy thatch and you’ll see more brown, dead grass blades amongst the green, living lawn than is desirable. Thatch should be removed when the buildup reaches 1” or more.
We’re going to explain how to prevent thatch, then we'll explain how to dethatch, plus the benefits of doing so.
Thankfully, there are easy techniques to incorporate into your lawn care routine to prevent thatch from building up in the first place.
Practice these good landscaping techniques to minimize thatch and you may never have to dethatch your lawn by mechanical means (dethatching is explained further below).
Rent a core aerator to remove plugs of soil/turf from your lawn. The holes left in your lawn are portals for air, water, and compost to seep into and benefit the soil.
After aerating, topdress with Soil³ compost to further improve the growing conditions and reduce thatch.
Microorganisms inherent in our Soil³ compost break down the thatch layer. They consume thatch and turn it into nutrients, thereby benefiting your lawn by improving the health of your soil.
We recommend aerating and topdressing with Soil³ compost once a year, when your lawn is fully green and actively growing.
That first number on the fertilizer bag is what most people recognize for getting the grass to grow. It’s the 16 in the 16-4-8 ratio. When overusing Nitrogen to push lawn growth unnaturally, it contributes to thatch. Stick to our recommended fertilizer rates for your type of lawn.
Yes, that machine in every garage – the lawn mower – is a tool for reducing thatch.
When your warm-season lawn builds up too much thatch, removing that debris layer becomes necessary. After you dethatch by these mechanical methods, going foward, establish the preventative techniques we explained above.
Core aeration will not quickly remove thatch, but it is the safest method for the health of your lawn. While topdressing with compost is one of the key prevention techniques, it will also mitigate thatch buildup because the microbes in Soil³ compost will break down the thatch over time.
Scalping is the term for removing the grass canopy, usually by a lawn mower set at a low cut height.
This is not the preferred method for dethatching, but you will see others scalping dormant Bermudagrass. We've hurt our own lawns scalping them – this procedure is that touchy.
We strongly recommend employing all the other methods we mention, rather than scalping.
This Bermudagrass lawn was intentionally scalped. Now we wait for green growth - will it start growing again? This is a scary time. If you scalp, water like crazy and fertilize to help the stolons sprout new growth.
Work the dethatching machine over your lawn in a crosshatch pattern by going back and forth in one direction (north to south), then back and forth perpendicular to that pattern (east to west). Plant debris will be brought to the top, which you can then blow off your lawn using a leaf blower.
You'll see a lot of thatch flying in this video because we forgot to attach the debris deflector plate. Attach that plate and it's less messy. We have also tried electric dethatchers and they work well too.
If you have a small lawn, all you need to do is get a leaf rake and rake out that thatch by hand. Like with the machine, you’ll bring a lot of dead plant matter to the top, which you can then blow off your lawn. There are also specific thatch rakes, if you like having specialized tools.
Dethatching with a leaf rake. It's fun! Rake deeply, but avoid tearing up the stolons too much. Then blow the piles of thatchy material off your lawn with a leaf blower.
You are now done dethatching. Straightforward, right? Even though it doesn’t take up much time (and raking is good exercise), it’s ideal to prevent thatch accumulation, rather than trying to fix it by yearly dethatching.
Time was, folks would torch their dormant warm-season lawns to burn up the thatch. Sod farms used to light up their sod fields too, but this practice was abandoned more than 50 years ago.
Greg Nichols (inside sales rep) warns that, "Dormant grass gets very dry and brittle, so fire moves very quickly." Because fire is the active ingredient, there are big problems with burning turfgrass:
Burning lawns is an old fashioned dethatching technique that is replaced by the preventative methods we explained: aerating/compost topdressing, regular mowing and smaller clippings, avoidance of extra amounts of nitrogen, and use of dethatching machines or rakes. To plainly state it again, "don't burn your lawn."
Dethatch warm-season lawns with runners, such as Bermuda, Zoysia, and Centipede, during different times of the year, depending on your method of choice.
The cool-season lawn we commonly grow in the Southeast is Tall Fescue. It grows in clumps, rather than by runners and thatch doesn’t build up in this type of lawn.
There’s no need to dethatch them! Those dead grass blades will break down quickly enough and benefit the soil.
Now that you’ve gotten a handle on the thatch situation, you’ll experience why your lawn benefits from a reduced thatch layer and you’ll get more satisfaction from it.