Issue 16, September 16, 2015
Aeration, core-cultivation, or soil aerification are interchangeable terms to describe the process of pulling plugs from the lawn, one of the best practices any homeowner or professional should do to turfgrass. It's not just for golf courses.
There is a direct relationship between root growth and top growth. The more the roots can grow, including deeper, the thicker the stand of grass. The lawn is also more drought-tolerant as the root system tends to be stronger. Aeration creates a looser soil, one with larger pores and less compaction. The result is better root growth.
Aerating in the fall, coupled with fertilizing and overseeding, can really thicken up the turf. Aeration also helps reduce thatch by placing a thin layer of soil on top of the existing thatch, helping break it down.
Most aerating machines pull a plug from the soil, usually about 2 to 3 inches deep, and spaced about the same. All the plugs makes it look like a gaggle of geese descended on the yard. But that's only temporary.
Core aerification (Cornell University).
Aerators only work on moist soil. If the soil is too dry, the machine won't be able to slice into the soil and pull the plug. If the soil is soggy, the machine just sits and spins, ripping up the lawn. Rain or a thorough irrigation 2 or 3 days before aeration should make the soil ideal.
Make sure the lawn is mowed before aerating. Set the machine to the appropriate depth and spacing. The following day or two after aeration, run the mower over the lawn to pulverize the plugs, which hopefully have dried. Some of the soil will filter down in the hole, but most won't. The holes will collapse inward, loosening the soil around it.
Fertilizing the turfgrass is recommended following aeration to encourage new root and shoot growth, and to hide the aesthetic injury aeration does to the lawn. Of course, watering is also necessary. Aeration is crucial on heavy clay soil, especially for sodded turf. In other words, the common suburban yard.
Spring aeration, coupled with fall aeration, is recommended for heavily compacted soils but remember there is more weed competition in the spring, especially with an opened turf. Be prepared to apply weed control.
Most lawns recover within three weeks after aeration and fertilizing. While it's best to aerate in early September, satisfactory results can occur even in mid-October. (David Robson)