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.
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.