Thatch
Lawn thatch is composed of a tightly intermingled layer of stems, leaves and grass roots, which accumulates between the vegetation and the soil. Too much thatch increases the turf’s susceptibility to lawn diseases, reduces its tolerance to drought, cold, and heat stress; and hinders the movement of air, water, fertilizers, and nutrients into the soil. In severe cases roots of the grass will not grow into the soil but only take root in the thatch layer making the turf susceptible to drought and heat stress.
Why Do Most Lawns Not Need Mechanical Thatch Removal?
If a lawn is building thatch faster than the microbes can break it down, this indicates that the lawn is lacking beneficial microbes. The cure to a thatch problem is not physical removal of the thatch, but by managing thatch in a lawn by stopping the improper cultural practices that are killing microbes in the soil. The cure to preventing and curing a thatch problem isn’t mechanical removal of the dead grass, instead it is to stimulate beneficial microbial activity in the soil.
99.99%+ of lawns DO NOT need to have the thatch removed via power raking or vertical cutting. Please contact your local lawn care expert before scheduling or performing a power rake service.
Thatch will accumulate in a lawn if the production of dead material (organic matter) exceeds the ability of the microorganisms in the soil to break down the organic matter. Thatch build-up occurs in lawns that have “dead soils” and thatch is a symptom of the absence of beneficial microbial activity. Thatch buildup happens if there is poor soil aeration and drainage. Improper lawn watering practices (usually too much water or too frequent water), cold soil temperatures, the use of chemical pesticides, and the use of synthetic fertilizers are all factors that increase thatch accumulation in lawns.
When a lawn’s thatch layer is greater than 3/4 of an inch thick it may need to be mechanically removed via power raking or vertical cutting.
Lawn Care Practices That Cause Thatch Buildup in Lawns
- Shallow or frequent lawn watering practices.
- Severe over watering of the lawn.
- Fertilizing the lawn with fast release nitrogen. Salt based nitrogen like those found in synthetic fertilizer sources will kill microbes in the soil.
- Mowing the lawn infrequently where more than 1/3 of the blade of grass is removed.
- The use of lawn herbicides and lawn fungicides. Both of these have been proven to kill microbial activity in soils.
- Compacted soils that have not been aerated annually.