The short version: thatch is a spongy layer of dead and living stems and roots that builds up between the grass blades and the soil. A thin layer is normal, but a thick, thatchy lawn suffocates the grass and is a common reason a North Texas lawn is slow to green up in spring. You can dethatch a small lawn yourself with a thatching rake, hire out lawn thatch removal on a bigger one, and prevent it going forward with proper mowing, deep watering, and relieving compaction. The rest of this guide covers how to spot lawn thatch, what causes it, and how to get rid of thatch in a lawn.
Every so often we notice a pattern across the lawns we treat: several lawns taking longer than normal to come out of dormancy in spring. On closer look, the combination of freezing temperatures over the winter and heavy downpour rains in spring points to one culprit. Dead thatch is to blame.
Counterintuitively, thatch tends to go hand in hand with highly maintained lawns, especially ones with creeping grass growth such as bermudagrass. If you take good care of your lawn and it still looks patchy and straw-colored when the neighbors' yards are greening up, this guide is for you.
What Is Thatch?
What is lawn thatch?
Lawn thatch is a layer of dead and living organic material (shoots, stems, and roots) that builds up between the green grass blades and the soil surface. A thin layer is normal. The trouble starts when the layer thickens faster than the soil life underneath can break it down, and the lawn becomes what people usually call a thatchy lawn.
The problem compounds itself: once a thick thatch layer develops, conditions in the lawn favor even more thatch formation.
What is thatch in a lawn made of, and why does it matter?
Thatch in a lawn is mostly the tough, slow-to-decay parts of the grass plant: stems, crowns, and roots, rather than the leaf clippings people often blame. It matters because once that layer gets thick, new grass roots grow into the thatch instead of the soil, so the lawn dries out fast, greens up slowly, and holds disease. That is the difference between a healthy thatch lawn with a normal thin layer and one where thatch has become a problem.
How to Spot a Thatch Problem
How do you know if you have a thatchy lawn?
Thatch problems progress in stages. Early on, you may notice small dull, tan patches where the green is thinning and dead material shows through at the base of the grass. At the moderate stage, the straw-colored layer becomes obvious across larger areas and the lawn feels spongy underfoot. Left alone, the damage stage follows: widespread dead patches where grass has been suffocated and struggles to recover even in good growing weather.
A lawn that is unusually slow to wake up from winter dormancy is often showing the effect of thatch rather than a fertilization or watering problem. A quick field test: cut a small wedge out of the turf and look at the brown, spongy band between the green blades and the soil. If it is more than about half an inch thick, you likely have a thatch lawn that needs attention.
The Damage Thatch Causes
Excessive thatch:
- Harbors disease-causing fungi and insects.
- Prolongs high humidity, which favors disease.
- Causes shallow root development.
- Retards the movement of air, water, fertilizer, and pest control materials into the soil.
As thatch builds up, the roots of new grass plants grow within the thatch layer rather than in the soil. When the lawn is exposed to hot, dry summer weather, those plants are unable to survive.
Zoysia and bermudagrass lawns can develop thatch layers rapidly but seldom die suddenly, since these grasses are more tolerant of heat and drought. In warm-season grasses, severe thatch usually shows up as thin, diseased turf instead.
What Does Not Cause Thatch
Fertilization, pre-emergents, and herbicides do not cause thatch. Your regular lawn program is not the problem.
Grass clippings do not normally cause thatch either. Clippings that are short enough filter down to the soil surface, where they decay. The exception is infrequent or improper mowing: long clippings cannot filter through the grass canopy to the soil, so they sit on top and add to the layer.
Heavy, compacted soils are a real contributor. Compacted soil does not allow the air, water, and nutrient exchange that favors microbial decomposition of the thatch, so the layer builds faster than it breaks down.
Preventing Thatch
- Moderate, regular fertilization of the turf to maintain vigor without excessive growth.
- Regular mowing that removes no more than one-third of the shoot growth in a single mowing.
- Watering as deeply and as infrequently as possible to encourage a deeper root system. Try to moisten the soil to a 6-inch depth when you water, then wait until the turf just begins to wilt before watering again.
- Where thatch has been a recurring problem, dethatch annually before the new flush of growth begins.
- Relieve compaction in problem areas with aeration to improve the penetration of air, water, and nutrients.
On mowing: mow often enough that no more than one-third of the shoot growth comes off at once. This keeps the grass from being stressed and keeps clippings short enough to filter down and decay. If the lawn has gotten away from you, remove one-third of the growth, wait a day or two, then mow again down to the desired height.
On compaction: because compacted soil is what starves the microbes that break thatch down, relieving it directly attacks the cause. Our microbial lawn aeration loosens compacted soil biologically, with no machine and no surface disruption, and one application keeps working for up to nine months.
How to Remove Thatch From a Lawn
Getting rid of dead thatch yourself
Dead thatch must be removed. Left in place, it will eventually suffocate and kill the grass. Lawn thatching, also called dethatching, is the process of pulling that dead layer out, and to get rid of thatch in a lawn you can either do it yourself or hire a professional company for lawn thatch removal.
For do-it-yourself thatch removal on a bermudagrass lawn, you will need either a thatching rake or a vertical mower. A thatching rake works well to remove lawn thatch on small lawns, while a vertical mower is better for bigger ones. Adjust the blades to the thickness of the thatch layer, and err on the side of removing too little: too much lawn thatching can permanently damage the lawn.
To prepare the lawn, mow the grass slightly shorter than usual and lightly irrigate. Dethatch the lawn twice, once in a horizontal direction and once vertical, so you don't miss any spots. Rake up the debris left on the lawn, then mow again to pick up even more. Finish with a good, deep irrigation.
Not Sure If Thatch Is Your Problem?
A slow, patchy spring green-up can have several causes, and treating the wrong one wastes a season. Our estimate is free: we analyze your lawn's condition, tell you honestly whether thatch, compaction, or something else is holding it back, and build a treatment plan around what your lawn actually needs.
