Core aeration is a beneficial turf maintenance practice that involves mechanically removing small cylinders of soil, thatch, and grass, known as plugs, from the lawn surface. This process primarily relieves soil compaction, which restricts the flow of air, water, and nutrients to the grass roots. After the procedure, the common question is whether these soil plugs should be removed or left scattered across the turf. The recommended answer is to leave the plugs where they fall, allowing them to naturally break down and reintegrate into the lawn.
Why Leaving the Plugs is Recommended
Leaving the soil plugs on the lawn surface is the most straightforward and beneficial approach for turf health. These cores are packed with organic matter and microorganisms from the soil’s subsurface. Allowing them to remain ensures these materials are recycled back into the grass ecosystem.
The plugs act as a slow-release topdressing, distributing essential plant nutrients across the turf. Nutrients like nitrogen, phosphorus, and potassium, which may have been locked away in the compacted soil, are returned to the surface layer. This process enhances the soil’s fertility without the need for external fertilization.
The soil cores also reintroduce soil microbes to the upper thatch layer and the new aeration holes. These microorganisms break down the thatch, which is a layer of dead and living organic matter that can suffocate the turf if it becomes too thick. Leaving the plugs promotes a healthier microbial environment that contributes to long-term thatch management and soil structure improvement.
This practice improves the overall soil structure by mixing the existing soil with the organic matter from the plugs. For lawns with heavy clay content, this redistribution of material can improve drainage and aeration on the surface as the plugs disintegrate. Essentially, leaving the plugs is a passive, yet effective, method of enhancing the lawn’s recovery and vitality.
The Natural Decomposition Process
The physical appearance of the scattered soil plugs is temporary, as they decompose and disappear naturally back into the turf. The primary catalyst for disintegration is water, whether from rain or irrigation. Moisture softens the clay and soil particles, initiating the breakdown process.
Warm, moist conditions significantly accelerate decomposition because they promote microbial activity within the plugs. Microorganisms consume the organic material, causing the plugs to crumble and flatten out. In optimal weather conditions, the plugs begin to break down noticeably within a few days.
The time it takes for them to fully disappear ranges from one to four weeks, depending on the soil type and environmental factors. Plugs on sandy soils break down faster due to better drainage, while those on heavy clay soils may take slightly longer. Homeowners can accelerate this process by light irrigation and mowing the lawn.
Mowing over the plugs physically breaks them into smaller particles, speeding up their reabsorption into the turf. This physical disruption, combined with consistent watering, ensures the soil material and recycled nutrients are quickly integrated back into the lawn’s surface. The goal is to avoid letting the plugs dry out completely and harden, as this slows the breakdown process.
When Plug Removal or Breaking Up is Justified
While leaving the plugs is generally the recommended practice, certain conditions may warrant removal or mechanical disintegration. One exception is a lawn with heavy clay soil, where the plugs can dry out and harden into dense pellets. If these hard plugs risk smothering the grass or creating an uneven surface, breaking them up is advisable.
Another scenario involves lawns with a history of severe lawn disease, such as patch diseases or active fungal infections. Removing the plugs is sometimes recommended to eliminate the infected soil and organic matter from the turf. If the lawn is heavily infested with problematic weeds, removing the plugs can prevent seeds and weed runners from being redistributed across the aerated surface.
Aesthetic concerns for highly visible ornamental turf areas or safety worries in high-traffic zones may also justify intervention. A dense layer of plugs can be visually unappealing and, in rare instances, a tripping hazard. In these situations, the plugs should be broken apart using a flexible lawn drag mat or a light pass with a rotary mower set at a high blade height.
The goal of intervention should be mechanical disintegration, not total removal, to ensure the recycled nutrients are retained. If plugs must be removed entirely, the material should be added to a compost pile to conserve the organic matter. However, breaking them apart and spreading the material thinly is preferable to raking them up and losing the topdressing benefit.