SPRING LAWN AERIFICATION AND DETHATCHING

Justin Quetone Moss

Spring is a great time to perform core aerification in the yard.  Core aerification is the process of removing small cores of soil and organic material from your lawn (Figure 1).   One can typically hire a lawn care company to perform this service or rent an aerification machine from a local equipment rental facility.  The aerification equipment typically is setup to pull cores ranging from 0.25 to 0.50 inches in diameter from the top 3-6 inches of the soil.  The cores are removed or can be left to decay on the lawn surface.  Bermudagrass has both aboveground stems (stolons) and belowground stems (rhizomes).  Over time, these dead stems and roots can create an organic layer just above the soil surface called thatch.  While a small thatch layer less than 0.5 inch is acceptable, thatch layers greater than 0.5 inch can cause problems in your lawn.  Aerification helps to break up the thatch layer, reduce soil compaction, increase water infiltration into the soil, and stimulate new root and shoot growth. A temporary disadvantage of core aerification is the disruption the turf area by bringing up soil to the surface which may result in a muddy or messy yard for several days. If there is an excessive thatch layer in the yard, de-thatching may be necessary via a machine called a vertical mower, also known as a verticutter or power rake (Figure 2). Small areas can be de-thatched by “power-raking” by hand using a standard rake to physically rake out the turf thatch layer. To prevent future excessive thatch buildup, one can employ the following turf management cultural practices as described in the OSU Cooperative Extension Service Fact Sheet HLA-6604 titled “Thatch Management in Lawns”:   

• Moderate and regular fertilization of the turf to maintain vigor without excessive growth.
• Regular mowing that does not remove more than one-third of the shoot growth in a single mowing.
• Watering as deeply and as infrequently as possible to encourage a deeper root system. Try to moisten the soil to a 6-inch depth when watering. Wait until the turf just begins to wilt before watering again.
• In situations where thatch has been a problem, dethatch annually in the spring before the new flush of growth begins using a vertical mower. 
• Core aerify compacted areas in order to improve penetration of air, water and nutrients.

Figure 1. Image representing core aerificaiton. Photo courtesy of Cornell University.

Figure 2. Image of a ‘Graden’ brand vertical mower or verticutter. Photo courtesy of Graden USA, Inc.