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What is thatch and how to prevent it in your lawn
Grass thatch is a tightly intermingled organic layer of dead and living shoots, stems, and roots that accumulate just above the soil surface of your yard.
It's not necessarily grass clippings even though they may contribute to the problem. Thatch accumulation is due to either over-fertilization, over-watering, and/or soil compaction of the lawn.
While a small amount of it is helpful as it helps regulate soil temperature and moisture of the lawn, too much of it interferes with air and water intake and makes proper lawn care difficult.
Too much of it can also reduce how effective fertilizers and pesticides are and increase disease and insect activity. Eventually, roots may start growing in the thatch, and since it does not hold much water, the lawn can become victim of drought.
For smaller yards less than 2500 sq.ft. and with minimal amounts of debris, a grass or thatch rake will do the job just fine.
The most common method for yards over 2500 sq. ft. is by using a dethatching machine. A dethatching machine is basically a power rake on wheels. Its blades or wires are vertical instead of horizontal and cut through the thatch to the ground surface and lift the old debris to the top of the lawn. You then rake up the mess and mulch it, compost it, or get rid of it.
You can usually rent a dethatching machine from a local rent company and do it yourself or get it done by a professional yard and lawn care company.
When using a dethatching machine to remove average amounts of thatch and to scar the soil, set the blades to cut 1/8 to 1/4 inch into the soil surface. Make a few test passes on an inconspicuous area of your lawn to judge how much thatch and turf will be removed. If too much or too little is removed, raise or lower the blades as you need to.
The spacing between blades can also be adjusted on some machines to work with different grasses. The blade spacing for Bermudagrass and zoysiagrass is 1 to 2 inches, while the spacing for bahiagrass and St. Augustinegrass is 3 inches.
If the thatch is thicker than a half inch, you'll have to run the machine over the area several times in different directions. You'll have to remind yourself that this is good for your lawn as it will look very rough for a while. Depending on your lawn type, it may be necessary to reseed.
On a lawn with thick thatch more than 1-1/2 inches, you may need to partially remove the thatch and allow the lawn to fully recover before the next dethatching session. Removing too much debris all at once can do more harm than good. The rule is to remove what you can without tearing up holes of more than a couple of square inches in live turfgrass. This may not be possible on lawns with very thick debris more than 2 inches. In that case, your may not be able to save the lawn and may need to reseed or re-sod from scratch.