Layer of thatch shown in a core sample

Excessive watering or fertilizing and improper mowing can cause turfgrass to develop a thick, spongy mat called thatch. Thatch is a layer of dead and living turfgrass that develops between your lawn and the actual soil. When excessive, thatch causes serious problems in Florida lawns. Thatch is an excellent habitat for insect pests and disease, makes mowing difficult, and reduces air and water flow in the lawn.

To control thatch, follow these recommendations:

  • Mow at recommended height and frequency.
  • Avoid indiscriminate use of fertilizer. Use minimal amounts of nitrogen, and soil test for phosphorus levels.
  • Maintain a soil environment conducive to rapid decomposition. This includes adequate aeration, irrigation, and soil pH control.
  • Core cultivation (aerification) can help control thatch formation and soil layering.
  • Topdressing with sand provides the best biological control of thatch. Proper timing and rates are necessary to provide the best thatch control with the least chance of disease occurrence.
  • Use vertical mowers if mechanical removal of thatch becomes necessary. Follow this with irrigation.

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