430-002
Authors as Published
Marc Aveni, Extension Agent, Prince William County; and David Chalmers, Extension Agronomist, Virginia Tech
What is lawn aeration?
Lawn aeration involves the removal of small soil plugs or cores out of the lawn. Although hand aerators are available, most aeration is done mechanically with a machine having hollow tines or spoons mounted on a disk or drum. Known as a core aerator, it extracts 1/2 to 3/4 inch diameter cores of soil and deposits them on your lawn. Aeration holes are typically 1-6 inches deep and 2-6 inches apart. Other types of aerators push solid spikes or tines into the soil without removing a plug (spiking). These are not as effective because they can contribute to compaction. Core aeration is a recommended lawn care practice on compacted, heavily used turf and to control thatch buildup.
What will aeration do for my lawn?
As lawns age or sustain heavy use from play, sports activities, pets, vehicle traffic and parking, soil compaction can result. Soil compacting forces are most severe in poorly drained or wet sites. Compaction greatly 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. It has a negative impact on nutrient uptake and water infiltration, in addition to being a physical barrier to root growth. This results in poor top growth and lawn deterioration. Core aeration can benefit your lawn by:
- Increasing the activity of soil microorganisms that decompose thatch.
- Increasing water, nutrient, and oxygen movement, into the soil.
- Improving rooting.
- Enhancing infiltration of rainfall or irrigation.
- Helping prevent fertilizer and pesticide run-off from overly compacted areas.
How do I know if I need to aerate?
>If in doubt about aeration, remove a square foot section of lawn at least 6 inches deep. If grassroots extend only into the first 1-2 inches, your soil may be compacted and could benefit from core aeration. Expect a seasonal effect with cool-season grassroots being shortest in late summer and at their greatest depth in late spring.
Other reasons to aerate include:
- Your lawn is heavily used or driven upon on a regular basis, causing the turf to thin or look unthrifty.
- The thatch layer is in excess of 1/2 inch.
- You have a heavy clay soil.
Is there any reason not to aerate?
A lawn that is not exposed to soil compacting events will likely grow well and may not need aerification. Winter freezing and thawing cycles and earthworm activity can help loosen slightly compacted soils. If the lawn has a thatch layer in excess of 1/2 inch, then core cultivation can be used as a preventative approach to control excess thatch build up. Newly seeded or sodded lawns should not be aerated in the first year.
When should I aerate?
In Virginia, the best time to aerate cool season lawns of tall fescue and Kentucky bluegrass is in late August to mid-September. This is when these lawns are coming out of summer dormancy and beginning a period of vigorous growth. Lawns will recover quickly from aeration at this time. Competition from weeds is also minimal during this time. Warm season lawns like bermudagrass and zoysiagrass are best aerated during June and July, as this is their period of rapid growth.
Aerification is the mechanical process of creating air space in the soil that promotes a healthy rooting system for natural turf. Healthy rooting systems are an integral part of a successful golf course and athletic field management programs.
