As lawns age, or sustain heavy use, soil compaction can result. This reduces the pore space within the soil that would normally hold air. Roots require oxygen to grow and absorb nutrients and water. Compaction reduces total pore space and the amount of air within the soil which can result in poor top growth and lawn deterioration. Lawn aeration involves the removal of small soil plugs or cores out of the lawn. Benefits include:
Increased activity of soil microorganisms that decompose thatch
Increased water, nutrient and oxygen movement into the soil
Help the prevention of fertilizer and pesticide run-off from overly compacted areas
More reasons to aerate include:
Lawns that are heavily used or driven upon on a regular basis, causing the turf to thin
Thatch layers that are in excess of 1/2 inch
Presence of heavy clay soil
If in doubt about aeration, remove a 6" deep square-foot section of lawn. If grass roots extend only into the first 1-2 inches, the soil may be compacted and could benefit from core aeration. Expect a seasonal effect with cool season grass roots their shortest in late summer and at their greatest depth in late spring.
In Georgia, the best time to aerate cool season lawns of tall fescue and Kentucky bluegrass is March through April or in October. This is when these lawns come out of their summer dormancy and begin a period of vigorous growth. Lawns will recover quickly from aeration and competition from weeds is minimal during this time. Warm season lawns, like Bermuda grass and Zoysia grass, are best aerated May through August as this is their period of rapid growth.