Lawn Thatch is a naturally occurring aspect of grass growth. Thatch is an organic layer that occurs between the grass crown and soil. It consists of shed and decomposing grass roots, grass stems, organic material, Stolens and rhizomes mixed together with living roots and grass tissue, insects and microbes.
Most cool season grasses are "bunch type" grass that don't buildup a lot of thatch. The cool season grasses that have the potential for building thatch are Kentucky Bluegrass, Creeping Red Fescue and creeping bentgrass. In the last several years, Rhizomatous Tall Fescue has been added to the list. While these can add to lawn thatch build up, they are rarely a problem and do not hold a candle to warm season grass thatch problems.
Warm season grass is more notorious about thatch build up. Bermudagrass, zoysiagrass, St Augustinegrass, Centipedegrass and many others are predisposed to thatch problems, especially in poorly managed turf. Bermuda grass thatch buildup can be problematic because some varieties grow fast and are aggressive spreaders.
Lawn thatch in itself can actually be a good thing. Healthy thatch levels can add several benefits to your grass and soil. A healthy thatch level is a thatch layer of 1/2 inch or less. It is a home to many beneficial soil microbes, earthworms and beneficial insects. It can hold moisture, provide cooling to soil roots and soften playing fields. It naturally filters pesticides from moving to ground water.
This is important if you have had thatch problems in the past: Beneficial soil microbes are responsible for keeping lawn thatch at safe and healthy levels. There are no chemicals that can do this for you. All natural Turf Formula helps keep your current microbe levels high and can fix many problems before they start.
What causes unhealthy levels of thatch?
The short answer is improper turf management. This is often a result on more intensively maintained turf, but it can easily happen on home lawns as well. Unhealthy thatch can be described as thatch that is too thick, from below 1 inch and up to several inches thick. When thatch reaches these levels it can cause serious problems.
Unhealthy Thatch Levels and Grass Roots Problems
When thatch gets too thick, grass roots will begin to grow only in the porous thatch since it is easy to penetrate and can often be more moist. This is especially true if the ground underneath is compacted or has other problems. The thatch becomes a divide between the roots and soil. Major problems occur when the thick, porous, spongy thatch dries out in hot weather. Dried out thatch can lead to grass injury or even kill grass.
In addition, thick thatch can become hydrophobic if it dries out completely during hot weather. Hydrophobic thatch loses its sponginess and can crust over, which repels water. This can become a permanent problem if left untreated. The water sits on top and the roots dry out. If on a slope, the water just runs off.
Disease Problems with Unhealthy Thatch
To make matters worse, the beneficial microbes numbers begin to fall and pathogenic microbes start to increase. Pythium Blight and Patch diseases tend to be more problematic where unhealthy lawn thatch is present. Standing water and poorly drained soils fuels pythium. There are many beneficial microbes that live by capturing and feeding on pathogenic microbes. With the beneficial numbers down, pathogenic microbe numbers start to rise.
How Unhealthy Lawn Thatch Starts
Excessive Nitrogen Applications: This is probably the number one reason for unhealthy thatch buildup. Nitrogen speeds up grass growth and the growth can easily out pace the decomposition of naturally shed roots and plant tissue. (Dr. Nick Christians) Understanding grass types and nitrogen rates during the year is extremely helpful. While there may be reasons for additional nitrogen at times, the tendency for the average homeowner is to apply more than is needed.
However, regardless of the percentages of Nitrogen listed on the bag, it is possible to apply the correct amount if you know how to do it. Please see our page on How to Calculate Fertilizer Rates below for help with this.
Beneficial Microbes are responsible for the breakdown of thatch and keeping it in check. Soil pH that is too Low or too high can affect microbial levels. As the pH drops below 5.5 or rises about 7.8 it begins to have detrimental impacts on soil microbes.
Adding Super-Cal can help by supplying immediately available calcium to plants and beneficial microbes. In soil tests starting with 2,500,000 microbe CFU/Gram in just 24 hours after apply Turf Formula with Calcium the microbes increased to 187,000,000 CFU/Gram. That is a tremendous increase!
Soil compaction is detrimental to soil life because it allows less water and air into the soil. Most plants draw in air through roots. In seriously compressed soil, water will sit on top with no where to go. If you have thick thatch on top of compressed soil, your grass can be in serious trouble.
How to Fix Lawn Thatch Problems - Dethatching Lawn Thatch
Lawn Thatch Removal Equipment: For thatch up to 1.5" thick, core aeration is recommended. Commercial core aerators should be able to penetrate to 3 inches deep and pull out a plug. Go over the lawn in multiple directions and try to get at least 30 holes per square foot. The holes will allow for air and water to reach below the thatch layer and allow for microbes to work better. Irrigate the lawn well after aeration.
For thicker thatch you may need to rent a vertical mower machine. It has blades that turn vertically instead of horizontally like regular mowers. These vertical blades slice the thatch and will tear a lot of it out. There is more mess to clean up with these machines, but they are often necessary to reduce the thatch and fix the problem.
Apply Turf Formula mixed with Super-Cal to the grass. Tested at the University of Missouri/Columbia, native, in soil beneficial microbes were increased by 3400% in 24 hours and 5000% in 72 hours. These beneficial microbes will consume thatch and organic material and convert them into humus and nutrients quickly. It increases nutrient and water uptake, increases root mass, and provides more efficient photosynthesis and much more. The Turf Formula and Super-Cal together form a bio-enhanced calcium that is extremely helpful for plants and soil. Using Turf Formula Prebiotic biostimulant on healthy thatch can help keep many problems from even starting. We provide full product support by phone or email.
Last but not least, correct the problems that led to thatch build up. We have everything you need on our website to learn how to do this correctly. If you can find it, use the search bar on the top right or shoot me an email.