Core Aeration: What It Is and Why Do It

Core aeration
Vít Švajcr/Wikimedia Commons/CC 3.0

Lawns require a lot of care. The tasks that come to mind are mowing, fertilizing, and clearing them of leaves and debris. But you can't forget aeration. Aeration is an essential aspect of lawn care.

Core aeration is a type of lawn aeration whereby a machine (a lawn aerator) with hollow tines mechanically removes plugs or "cores" of soil and thatch from a lawn. Core aeration reduces soil compaction, creating a channel through which oxygen, water, and nutrients can penetrate the soil.

What Is Core Aeration?

Core aeration is a type of aeration that extracts plugs of soil from a lawn in order to increase air flow.

There are other ways to aerate a lawn. For example, some lawn aerators drive solid tines into the earth. But that method isn't considered as effective as core aeration, in which you're creating holes of a significant diameter—1/2 inch to 3/4 inch. Likewise, you could plunge a pitchfork into the grass every X number of square inches, but that's not feasible for most people.

Here's what you should know about core aeration, and how it can benefit your lawn.

Why Core Aeration Is Important

Picture the soil under a healthy lawn. It's a soil studded with networks of air pockets. Oxygen travels through these pockets, and that's important: Just because grassroots are underground, that doesn't mean they don't have to breathe! But it's more than just oxygen that must percolate down through the ground, as your grassroots also need water and whatever nutrients homeowners are supplying when fertilizing lawns. There's a veritable beehive of activity going on down there under a healthy lawn.

Now consider the soil under the grass that is performing poorly. Instead of being fluffy enough for oxygen, water and nutrients to flow through it (down to the grassroots), it is compacted. It may also be crowned with a thick layer of thatch, rendering it even more impervious. This lawn is crying out for core aeration.

Core aeration creates those pockets of air that allow oxygen, water, and nutrients to move through the ground.

Core Aeration Helps With Moss Problems

Many people complain about having moss plants growing in their lawns, and they'll proceed to wage a campaign against the moss, thinking that all that is needed is to apply the correct herbicide. This is a misguided policy. Lawns that drain poorly due to compacted soil and/or thatch might just as well be displaying a sign that reads, "Moss Welcome Here." Compacted soil is a common problem for lawns subjected to excessive foot traffic (as when kids play on the lawn frequently).

Core aeration helps reduce the compaction of the lawn.

The Best Time for Core Aeration

For cool-season grasses, perform core aeration in early fall. For warm-season grasses, the time generally recommended for core aeration is mid-spring to early summer.

The one time you definitely shouldn't aerate your lawn—no matter whether you have cool- or warm-season grasses—is when the weather is particularly hot and dry.