Lawn aeration combats soil compaction by removing plugs of earth and thatch in a pattern that spans the entire grassy area. It enhances a lawn's overall health and look by improving the soil's ability to absorb water and nutrients, which may then reach the grass' roots. If you perform this task consistently, your lawn will be healthier with strong and deep root growth.
Pick the Right Time
Aerate your lawn once a year. If you grow cool season grass---this includes bluegrass, ryegrass and tall fescue---pick a late August or early September date. For warm season grasses, such as Bermuda or St. Augustine varieties, choose a day in June or July. These time frames coincide with the grasses' growth seasons, which allow the lawn to quickly recover from the aeration.
The exception to this suggestion is a recently established lawn that is newer than one year; do not aerate it. Moreover, if your soil consists of heavy clay, consider aerating twice a year. Choose spring and fall as your calendar markers for this task.
Choose the Right Equipment
Soil compaction most likely affects the upper four inches of your lawn surface. Rent an aerator from your local home improvement store or nursery that will address this problem. There is no need to purchase your own aerator, since this is a tool you only use once or twice a year.
Pick a model with hollow tines--not spikes---measuring about four to six inches in length; ask for this equipment by requesting a core aerator. Hollow tines extract soil cores, while spikes merely puncture the soil. Although the spikes provide short-lived aeration, they actually do not offer a long term solution.
Moisten the Soil Prior to Aeration
Attempting to aerate compacted soil is difficult and might not yield good results; therefore, moisten your lawn surface prior to aeration. Water runoff may be a problem with compacted soil, and it is a good idea to spend two days of intermittent watering to reach desired moisture levels. Water just enough to wet the surface and then give the soil a chance to absorb the water. Repeat this process as needed. This greatly reduces runoff. Do not overwater, since you do not want the soil to be wet. The Virginia Cooperative Extension suggests using the cumulative equivalent of one inch of water to sufficiently moisten the soil.
Aerate in Two Directions
Mark your sprinkler head locations with little flags to avoid damaging them with the aerator. Aerate your lawn by walking the aerator first in a vertical direction across the lawn and then in a horizontal direction. The goal is to minimize compaction by maximizing coverage of the lawn's surface.
Seed or Fertilize After Aeration
Leave the extracted plugs on the lawn. Watering will break down the plugs, and the soil works its way back into the lawn area. Fertilize or seed your lawn right away, as needed. Do not apply top soil to newly seeded areas, but instead rely on the soil from the plugs to eventually cover the seeds.