Aerating Lawns: the What, Why, How, and When
What is Aeration?
Aeration, sometimes called “core aeration,” consists of perforating the soil (and any thatch above it) with small holes that remove cores of soil, thatch and grass. This allows water, air and fertilizer to get closer to the grass’ roots, which enables them to grow more deeply, producing a more vigorous lawn. In tests, grass roots have been shown to proliferate around the holes. Aerating will also improve soil compaction and reduce the likelihood of thatch becoming an issue.
Why Aerate?
Poor drainage, failure to turn green after fertilizing, and the presence of many worn areas may signal the need to aerate. Intensively maintained lawns (those that receive regular fertilizer feedings) should be aerated about once a year; those receiving moderate maintenance (not much ferilizer) need aerating every two years or so.
When to Aerate?
If you live in the South, then aerate in the spring. If you live in the North, then aerate in the spring or the fall. If you have a St. Augustinegrass lawn, consult a professional about aerating.
How to Aerate
You can contact a lawn care company. (Tip: call a month or so in advance as they will be busy serving other customers.) For new lawnowners or for those strapped for time, hiring someone to do it for you is highly recommended.
To aerate a lawn, use a specialized tool to remove plugs from the soil. You can purchase or rent a motorized aerating machine from a tool rental company or a garden center. To be effective, individual holes should be at least ¾ inch in diameter, 3 inches deep, and no more than 3 inches apart. Run the aerator over the lawn several times to make enough holes.
Select the type of aerator that removes a plug of soil. Some aerating tools punch nail-like spikes into the sod without removing plugs. Because this type compresses the soil around the hole, it is less effective that the type that removes plugs.
Make sure the soil is moist during aeration—neither too wet nor too dry—so the aerating device can penetrate it fully. You may have to water it first.
The plugs of soil the machine removes are deposited on the surface of the lawn. Leave the plugs to dry for a day, then break them up with energetic raking or by mowing with a side-chute lawn mower. This creates a thin, beneficial top dressing. If you don’t mind their appearance, you can just leave them to deteriorate in rainfall or irrigation. They will disappear in a couple of weeks.
After Aerating
An aerated lawn will recover faster if fertilized and watered adequately. Apply fertilizer as soon as possible, and water whenever rainfall fails to supply about one inch of moisture per week. If the lawn is thin, overseeding with a high quality grass seed is recommended.