Core aeration involves mechanically removing small plugs of soil and thatch from the lawn. This helps relieve soil compaction and allows air, water, and nutrients to better penetrate the root zone. Proper preparation is necessary to ensure the success of this process. Mowing is a preparatory step that directly influences the efficiency and effectiveness of the aeration equipment.
Why Mowing Height Matters for Aeration
Mowing the lawn to a lower height immediately before aeration ensures the coring machine’s tines reach the soil with minimal obstruction. Taller grass blades and excessive thatch interfere with the aerator’s function, preventing maximum penetration depth. A shorter turf profile allows the machine to operate cleanly, ensuring the removal of soil cores that are typically two to three inches long.
The general recommendation is to reduce the grass height to 1.5 to 2 inches, or about one-third lower than the turf’s normal cutting height, without “scalping” the lawn. For common cool-season grasses like Kentucky Bluegrass, this lower cut clears the way for the hollow tines to enter the ground efficiently. This intentional short cut aids the machinery and provides an advantage if overseeding is planned, ensuring better seed-to-soil contact.
This lower cut also helps expose the soil surface, allowing subsequent grass seed or fertilizer to fall directly into the newly created aeration holes. When the tines penetrate the soil more effectively, deeper and wider cores are pulled. This directly translates to better oxygen flow and root development. The temporary stress placed on the grass is quickly offset by the profound benefits of the upcoming soil treatment.
Preparing the Lawn Beyond Mowing
Beyond a pre-aeration mow, managing the soil’s moisture level is the most important preparation to facilitate optimal core extraction. The ground should be thoroughly watered about one to two days before the scheduled aeration, aiming to moisten the soil to a depth of four to six inches. Moist soil allows the aerator tines to smoothly punch through and pull out full, intact soil plugs, which are approximately a half-inch to three-quarters of an inch in diameter.
Soil that is too dry will be excessively hard, causing the aerator to struggle for penetration and potentially resulting in shallow or incomplete cores. Conversely, soil that is waterlogged or muddy will clog the tines of the machine, preventing the removal of plugs and potentially causing soil smearing, which negates the aeration benefit. Check the soil moisture by pushing a screwdriver into the ground; if it penetrates with little resistance, the moisture level is appropriate.
Prior to starting the machine, identify and clearly mark all underground obstacles to prevent expensive damage. This includes outlining the location of shallow irrigation pipes, sprinkler heads, in-ground lighting wires, and any invisible pet fences that may be buried just beneath the surface. Removing surface debris, such as large sticks, stones, or matted leaf litter, is also required to ensure the aerator passes smoothly without jamming or breaking tines.
Immediate Steps Following Aeration
Once the aeration process is complete, the soil plugs, or cores, should be left on the surface of the lawn to decompose naturally. These plugs contain microorganisms and organic matter that will break down within a few weeks. This decomposition essentially top-dresses the lawn, reintroducing nutrients and improving the texture of the surface soil.
Immediate deep watering is required following aeration, especially if overseeding or fertilizing is planned. The newly exposed soil and roots are vulnerable to drying out, so watering maintains moisture and helps the grass recover. Watering also assists in settling new seed and fertilizer into the aeration holes, maximizing their effectiveness.
Aeration creates the perfect environment for overseeding. Applying grass seed immediately after the treatment ensures the seeds fall directly into the open holes, achieving superior seed-to-soil contact for better germination rates. Following seeding, a starter fertilizer should be applied within 24 to 48 hours. This provides the necessary phosphorus and nitrogen to support new seedlings and established roots.