It’s important to periodically check your lawn for thatch, a brown layer of mainly dead grass that accumulates in some lawns between the green grass blades and the soil surface. Thatch can easily go unnoticed, causing serious damage to a lawn before an unsuspecting homeowner even realizes a problem exists.
A thin layer of thatch may actually have some benefit, helping regulate temperature and moisture, but once the layer reaches critical mass, it’s time to dethatch.
What Does Lawn Thatch Look Like?
Identifying a Lawn Thatch Problem
To inspect your lawn for thatch:
- Push a wide knife or hand hoe into the grass
- Rock back and forth until you reach an inch or so into the soil
- Gently pull back the grass and inspect the area just above the soil line
If you see little or no brown material, you are in the clear.
However, if you see a brown layer of thatch 1/2 inch or thicker, take action.
Can Thatch Damage Your Lawn?
A dense thatch layer essentially chokes your lawn by preventing life-sustaining air, water and nutrients from circulating properly. Lawn thatch holds onto moisture at the soil surface, causing grass to develop shallow roots, which in turn makes your lawn less hardy and less drought tolerant.
The moist thatch environment also creates favorable conditions for infiltrating fungus, insects and disease. Bottom line—if left unchecked, thatch can weaken and eventually kill your grass.
What Causes Lawn Thatch?
It’s a common myth that thatch develops from grass clippings. Once thatch has become a problem, excessive grass clippings can contribute to thatch, but clippings do not cause thatch.
Some lawns are more likely to develop a troublesome thatch layer than others. Warm season grasses like Bermuda and zoysia, for example, are naturally more susceptible to thatch issues than cool season grasses like tall fescue. Also, lawns with balanced pH and well-draining soil are less likely to develop problems, whereas lawns that get overwatered or over-fertilized are more likely to develop thatch buildup.
Avoiding Thatch Buildup
If your grass has a thatch layer of less than 1/2 inch, these lawn care tips will help keep it in check.
- Irrigate less often but more thoroughly to encourage deep healthy grass roots.
- Avoid overuse of nitrogen fertilizers, which leads to excessive growth and thatch buildup.
- Mow frequently, removing only 1/3 of the grass blade at a time.
- Use a lawn aerator once or twice a year, especially if you have clay or compact soil.
- Avoid nonselective pesticides, formulated to kill a wide variety of pests. General pesticides can kill earthworms, which help break down thatch naturally.
How to Remove Thatch from Your Lawn
If your thatch layer already exceeds the 1/2-inch mark, we recommend you call in a trusted professional to dethatch. Most solutions require specialized equipment and heavy labor.
Aerating your soil can be curative as well as preventative. Rent a power aerator or hire a professional.
Vertical mowing and power raking involve the use of specialized power tools to break up the thatch layer. Both tools can be rented, but be careful. Used incorrectly, they can easily do more harm to your grass than good.
The Best Time of Year to Dethatch
Dethatching promotes growth, so excessive lawn thatch should be removed during the growing season. Warm season grasses like Bermuda, zoysia or centipede should be dethatched in early to mid-summer.