Core aeration is a lawn maintenance practice that involves mechanically removing small cylinders of soil, typically half an inch to three-quarters of an inch in diameter, from the turf. This process relieves soil compaction and creates channels for air, water, and nutrients to penetrate the root zone. After aeration, the lawn is scattered with these soil plugs, leading to the question of whether they should be collected. The direct answer is that in nearly all instances, the cores should be left exactly where they are on the lawn surface.
The Primary Rule: Why Cores Must Remain
The primary function of the cores is to break down naturally and filter back into the turf, acting as a natural top-dressing. These plugs are filled with nutrients and microorganisms from the soil and the thatch layer. As they decompose, they recycle these elements directly back into the ground, benefiting the grass roots.
Leaving the cores on the surface ensures their components are redeposited into the soil profile. The aeration process creates thousands of open holes, allowing the fragmented material to work its way into the root zone easily. This reintegration improves the overall soil structure and encourages stronger, deeper root growth.
Understanding Core Composition
The cylindrical plugs ejected by the aerator are a concentrated mix of materials pulled from the upper soil layer. Each core contains a blend of compacted mineral soil, fine grass roots, and organic matter from the thatch layer. This organic material is rich in beneficial microorganisms that support the lawn’s ecosystem.
Returning this material to the surface reintroduces these helpful microbes, aiding in the ongoing decomposition of the remaining thatch layer. As the cores crumble and settle back into the aeration holes, they create a more favorable environment for nutrient cycling and soil health.
Accelerating Core Reintegration
While the cores will eventually break down on their own, homeowners can take steps to speed up their reintegration into the lawn. The most effective method is applying water immediately after aeration. Consistent watering softens the dry, compacted soil cores, causing them to crumble more quickly.
Running a lawnmower over the area a few days later is another practical way to accelerate the process. The mower blades mechanically break up the plugs into smaller particles, which settle more easily down to the soil surface. This reduces the time the plugs are visible, usually resulting in their disappearance within one to two weeks.
When Core Removal Becomes Necessary
While removing cores is generally not recommended as it deprives the lawn of recycled nutrients, there are a few exceptions where removal or redistribution is necessary.
Exceptions for Core Removal
If the homeowner plans to immediately apply a top dressing of compost or sand, the cores are sometimes raked away to ensure a clean, level surface for the new material.
High-traffic areas are a second scenario, where wet cores can be mashed into a muddy, uneven layer on the turf surface, potentially smothering the grass beneath.
If a homeowner is immediately overseeding, a cleaner seedbed is sometimes desired to ensure maximum seed-to-soil contact.
In these rare instances, the cores can be collected, though they should ideally be repurposed in garden beds or compost piles rather than discarded.