Core aeration is a mechanical process designed to alleviate soil compaction and improve lawn health. This involves a machine with hollow tines extracting small plugs of soil and thatch, typically measuring 1/2 to 3/4 inches wide and 2 to 4 inches deep. These perforations create channels that allow oxygen, water, and nutrients to better reach the grass’s root zone, encouraging deeper, vigorous growth. Proper care before and after this treatment is necessary to maximize its benefits, especially regarding the timing of mowing.
Preparing the Lawn Before Aeration
Preparing the turf before the aerator arrives helps ensure the machine works effectively. Cut the grass shorter than its usual height, ideally one to two days before the scheduled aeration. This preparation is important because a shorter blade length allows the aerator’s tines to penetrate the soil more easily and consistently.
The recommended height for this pre-aeration cut is typically between 1.5 and 2 inches, but avoid cutting the grass so low that it causes stress or “scalping.” Keeping the grass short also ensures the ejected soil cores land cleanly on the surface rather than getting suspended in tall grass blades. These plugs are meant to decompose naturally, and their uniform placement facilitates this process. Mowing also removes any excessive thatch layer that could interfere with the aerator’s function or the subsequent breakdown of the plugs.
The Mowing Delay: Cutting Grass After Aeration
The question of whether you can cut the grass immediately after aeration is answered with a recommendation for patience. The soil plugs left scattered across the surface are an intentional part of the process and must be allowed time to break down. Mowing over them too soon can disrupt their natural decomposition, which returns beneficial microbes and nutrients to the soil.
Attempting to mow immediately can also be detrimental to the lawn’s recovery and your equipment. The heavy weight of a mower, combined with turning, can re-compact the soil directly around the newly created holes, partially defeating the purpose of aeration. This re-compaction hinders the movement of air and water into the exposed root zone.
A waiting period of 7 to 14 days is advised before the first cut after aeration. This duration allows the soil cores to dry out and begin to crumble, aided by watering and weather cycles. If you have chosen to overseed immediately following aeration, the delay is even more important to protect the delicate, germinating seeds.
Running a mower over the soil plugs before they have sufficiently broken down causes unnecessary wear and tear on the mower blades. The blades will repeatedly strike the dried, dense soil, which dulls them quickly. Waiting for the cores to disintegrate ensures the soil’s benefits are retained and the turf is ready to tolerate the stress of mowing.
Post-Aeration Mowing Technique
Once the waiting period is complete and the majority of the soil plugs have dissolved, you can prepare for the first post-aeration cut. This initial mow should prioritize the health of the newly exposed root system. Return to your normal, higher mowing height, avoiding the temptation to cut the grass short.
Using a mower with a sharp blade is beneficial during this time, as a dull blade can tear the grass blades, leaving them vulnerable to disease and stress. Sharp blades ensure a clean cut, promoting faster healing for the turf. If you notice any stubborn, remaining soil cores, consider using the mower’s bag attachment during the first pass to collect the debris.
Alternatively, a light raking or dragging a piece of matting across the lawn before mowing helps shatter the final plugs and scatter the remaining organic material. Following these steps helps transition the lawn back to its regular maintenance schedule without compromising the structural improvements made by aeration.