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Timely Tip – Core Aeration

Why aerate your lawn?

Break up hard-pan clay soils - Soils in the Delaware Valley contain high amounts of fine-particle clays, and our hot summers act like a kiln, baking the clay into a seemingly impenetrable, compacted hard-pan.  Aeration will break up hard-pan clay soils so that grass roots can penetrate deep into the ground this fall and become the lawn’s lifeline to reserves of water next summer.  Opening up the soil structure through aeration will also significantly increase the movement of air, moisture and fertilizer through the soil.
Reduce Thatch – If your lawn has a thick layer of thatch, core aeration will punch through that layer and improve air, water and nutrient penetration to the root zone.  Additionally, the pulled cores of soil that are deposited on top of the thatch inoculate the thatch with beneficial soil micro-organisms that help break it down.  Maintaining thatch at no more than 1/2” contributes mightily to a healthier lawn that is better able to withstand drought, disease and insect stress.  

Reduce Water Requirements – By relieving soil compaction and thatch, water penetration is increased, and water run-off is reduced. 

How is aeration done?

The hollow coring tines of the mechanical aeration equipment puncture the soil, systematically removing small soil plugs. The cores of soil and thatch are pulled up by the machine and left on the lawn, as they contain beneficial microorganisms that will help to break down the remaining thatch. They will disappear back into the lawn in 7 to 10 days with mowing and rain. Raking the cores to break them up will speed their disappearance from the lawn surface but is not necessary. 
When is aeration done?

As a measure of the importance of aeration, it should be noted that golf courses will often aerate 4-7 times per year.  For homeowners in southeastern Pennsylvania we recommend lawns with normal thatch layer thickness of less than ½” be aerated once per year in the fall.  Lawns with heavy thatch, including most newly sodded lawns, should be aerated twice per year until the thatch layer is less than 1/2'” thick.  Aeration can be done in the spring, but the window of opportunity is narrow.  Spring aerations must be done after soil saturated with melting snow water dries out and becomes friable and before pre-emergent crabgrass control is applied.