Thatch is the layer of dead material and organic matter between the soil surface and grass. It gives Florida grasses a sponge-like feel under the feet that springs back when you step.
This layer can be a double-edged sword. It provides many benefits but if left to accumulate can have a negative impact on the turf. The most common turfs in Florida experience thatch. Those grasses are St. Augustine, Zoysia, Bermuda, and Centipede grass.

What are the benefits of having thatch?
It gives the turf more organic matter which can help to reduce the need for fertilizer applications.
Insulates the soil from excessive heat or cold.
It helps reduce damage from heavy traffic.
It can help reduce erosion from heavy rainfall.
Water retention, reducing the need for frequent irrigation

What is the negative side of too much thatch?
Can block water and nutrients from reaching the soil surface
Can be a great place for diseases and pests to find a home
Decline in the quality of turf, by increasing the need for water by not allowing water to reach the soil
Compaction
Increased risk of heat stress, by insulating too much heat and not enough water.

Practicing proper lawn maintenance can help to prevent excessive thatch, it’s okay to have thatch in your turf, but too much can lead to problems.
Thatch removal or aerating may be a necessary step if there is too much, and issues are occurring.

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