Aerating Your Lawn

Living creatures need air, and the roots of your turfgrass plants are no different. Unfortunately, soil can become compacted over time, making it too dense to effectively allow air, water, and nutrients to reach grass roots. Compacted soil slows and can even stop grass from growing.

Aeration—the process of creating openings in the soil structure—is the cure for compaction. It literally opens up the soil, bringing essential air and water to the roots, while allowing those roots a loose structure through which to spread. Aerating your lawn prevents thatch buildup (and can alleviate an existing thatch problem), ensures that fertilizer finds its way deep into the soil rather than languishing on top, and generally creates a very hospitable environment for beneficial microorganisms.

The aeration process is simple. It involves pulling cores of soil out of the ground and depositing them on top, where they will dry out and break up naturally. The holes left behind are made at regular intervals about 3" apart.

You can use any of a number of manual aerators available on the market, but the most effective and quickest way to aerate is to rent a power core aerator. This machine features rows of hollow tines on a roller or other device. As you move it forward, the tines jab down into the soil about 3" deep, pulling up cores and ejecting them onto the lawn.

No matter which kind of aerator you use, be sure that the soil is slightly moist; if it’s too wet, it will bog down the machine or manual aerator, and mud will fill in the holes. If it’s too dry, you’ll have a very rough go of it as the machine struggles to penetrate the surface.

You’ll also need to plan the right time for aeration. Cool-season lawns should be aerated in late summer to early fall, while warm-season lawns are aerated in late spring. Adjust this time a bit to ensure that you don’t aerate during the germination period for weeds common to your area. Because it’s gentler on the lawn than dethatching, you can aerate once a year. Follow up aeration with a topdressing of compost or other organic amendment to get the most out of the process. Water deeply after you’re done. Post-aeration is also a good time to overseed the lawn and feed it with a light application of fertilizer.

The Compaction Test

You can determine if your lawn is a candidate for aeration with a very simple test. Try sticking the point of a long Phillips head screwdriver into your soil. If you have a hard time pushing it in, it’s a good sign that the lawn is overdue for aeration.

Power aerating your lawn creates openings for air and nutrients to get deep into the root system. It also creates hundreds of dirt cylinders that can be left to dry and then worked back in.

How to Use a Power Core Aerator

Water the entire yard lightly a few hours before you aerate to ensure that the soil is moist—but don’t overwater or you will bog down the machine in mud.

Flag all sprinkler heads, shallow sprinkler lines and shallow buried cables, wires and utility lines. Clear the lawn of other debris such as small tree branches.

Set the depth gauge on the coring machine to maximum. Run the machine across the lawn, back and forth in one direction. Then run it again, perpendicular to the original direction.

Allow the cores pulled up by the aerator to dry for a day, then gently rake across them to break them up so that they decompose more quickly.