Thatch in St Augustine Lawns


By Rick Orr 04/17/2020
Soil Profile below a St Augustine Grass Lawn with a ruler showing depth
Below the canopy of a St Augustine lawn, the conditions are moist, cool, dark and windless. This is perfect for the composting of organic matter that can form a thatch layer

What is Thatch

Thatch is a layer of organic matter on the soil surface that forms when conditions prevent the enzymatic digestion (composting) of organic matter. Thatch forms a barrier to oxygen, water, and nutrients. It is a dead zone above the soil that chokes the life out of anything below the thatch.

The solution for thatch is to provide the conditions needed to compost organic matter - moist, cool, dark and windless conditions just above the soil surface where organic matter collects.

An Augustine Lawn is Thatch Free

A St Augustine lawn kept tall and wet always has moist, cool, dark and windless conditions at the soil surface. The tall canopy shades and cools the soil and blocks the wind. An irrigation system or rain keeps the organic matter wet and the tall canopy stops evaporation of the moisture. Any organic matter that collects on the soil surface in a St Augustine lawn is composted into plant nutrients.

Composting is the enzymatic digestion of organic matter (OM) by bugs, worms, microbes, fungi, and algae that thrive in the moist, cool, dark, and windless conditions below the canopy. Bugs and worms chew, grind and digest the OM. Microbes, fungi, and algae further process the OM that is eventually used by the St Augustine plant as food. It is a sustainable food system for the lawn.

St Augustine Lawn Lives Above Ground

St Augustine lawn is made of thick above-ground stems with large open space between stems and a tall stiff canopy above the stems. It is this mat of stems and stiff canopy that is often – and wrongly – called thatch. This mat of stems and tall canopy is what provides the moist, cool, dark and windless conditions to prevent thatch.

Fat Grass

During peak growing conditions – hot, rainy and open sun – the growth rate can be excessive in areas of the lawn. The stem mat becomes excessive and mowing is difficult due to the spongy character of the lawn. This is not thatch – it is fat grass, where too much grass is growing in too little space. This is self-correcting. As peak conditions wan, the growth will slow, and the fat grass will become slim again.

Mowing Height is Critical for Composting

Mowing height is critical for composting and protection of stems and roots from the hot Florida sun. Mowing heights of 4” or higher will provide a thick tall canopy providing optimum light reception, insulating of the stems from the harsh sun and perfect conditions for composting. That is a win/win/win – high photosynthesis, max protection for the stems and composting.

Good Action Plan for Thatch in St Augustine Lawns

The spongy cushiony feel of a St Augustine lawn is natural and necessary for the survival and health of a St Augustine lawn and composting of organic matter. For best results keep the lawn tall and wet - mow your lawn at 4” or higher and spend your time and money improving your irrigation system and don’t worry about thatch.

Rick Orr Owner-Operator APL Pest Control/Creator of ILOVETURF.COM
APL Pest Control

Rick Orr is the creator of, Owner/Operator of APL Pest Control and a graduate from VA Tech in Agronomy (Turf Ecology).  

Since 1980, Rick worked in the green industry, mostly with golf courses, resorts and large communities. Rick worked as a Golf Course Superintendent of Fripp Island Resort, agronomist for Seaside, FL and the spray tech for Vinoy Golf Course. Rick has been certified as an arborist, landscape and irrigation contractor and adjunct professor for Environmental Horticulture (SPC) in Pinellas County.  

Home Pest Control came naturally. Entomology (bug science) was part of agronomy studies. Nearly every indoor pest problem starts outdoors. Crossing over to home pest control from lawn spraying was a natural process – the technology, methods and materials used for home pest control are modifications of the ones used for lawn spraying. 

The results of that work is a one of the top rated pest control companies in Pinellas County – APL Pest Control. APL Pest Control is a family owned business serving residential and commercial properties in Pinellas County, FL. 

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Speaking Engagements - Does it seem like you are only hearing one side of water restrictions, fertilizer bans, plant restrictions, and many other urban landscape hot topics? Rick Orr is available for speaking engagements for your HOA, Community or Professional Association or Garden Club about a variety of subjects. To contact Rick you can find him on FacebookTwitterLinkedIn and Instagram for booking information.