What is Lawn Aeration or Aerification?
Technically speaking, aeration is the naturally occurring process of air exchange between the soil and its surrounding atmosphere. Practically speaking, aeration is the process of mechanically removing small plugs of thatch and soil from the lawn to improve soil aeration. The aeration process is also commonly called core aeration in the lawn service industry.
What are the Benefits of Aeration?
Core aeration helps the lawn’s health and vigor, and it reduces maintenance requirements. The following are other benefits of core aeration.
- Improved air exchange between the soil and atmosphere.
- Enhanced soil water uptake.
- Improved fertilizer uptake and use.
- Reduced water runoff and puddling.
- Improved turfgrass rooting.
- Reduced soil compaction.
- Enhanced heat and drought stress tolerance.
- Improved resiliency and cushioning.
- Enhanced thatch breakdown.
The type of aeration equipment used influences the benefits obtained from aeration. Equipment with hollow tines removes soil cores. Aeration equipment varies in tine size up to ¾ inch and in depth of penetration up to 3 inches,
Penetration depth depends on soil type, soil moisture, tine diameter, and the weight and power of the aerator. Penetration is better in moist soils than dry soils and will differ from lawn to lawn.
Why is Aeration Necessary?
In most home lawns, the natural soil has been seriously disturbed by the building process. Fertile topsoil may have been removed or buried during excavation of the basement or footings, leaving subsoil that is more compact, higher in clay content and less desirable for healthy lawn growth. These lawns need aeration to improve the depth and extent of turfgrass rooting and to improve fertilizer and water use.
Intensively used lawns are exposed to stress from traffic injury. Walking, playing and mowing are forms of traffic that compact soil and stress lawns. Raindrops and irrigation increase soil density by compacting soil particles and reducing large air spaces where roots may readily grow.
Aeration helps heavily used lawns and lawns growing on compacted soils by improving the depth and extent of turfgrass rooting, allowing better water uptake, enhancing fertilizer use and speeding up thatch breakdown.
Most home lawns are subject to thatch accumulation. If thatch is left un-managed, it can lead to serious maintenance and pest problems. For example, thatch accumulation of more than ½ inch on Kentucky bluegrass lawns impedes water; fertilizer and pesticide effectiveness. Core aeration reduces thatch accumulation, minimizes its buildup and modifies its makeup by incorporating soil into the thatch.
Thatch accumulates faster on compacted soils, heavy clay soils and subsoils that are disturbed during building processes than on well-aerated soils. Therefore, lawns require frequent aeration to prevent thatch buildup. Most home lawns growing on heavy clay or highly compacted soils require annual aeration to restrict thatch accumulation.
When Should Lawns Be Aerated?
Annual aeration is beneficial for most lawns. The University of Guelph Turfgrass Institute recommends aeration be done in either Spring or Fall at least once per year. Lawns growing on heavy clay or subsoils, and lawns exposed to intense use benefit from more than one aeration each year. Most turf grasses respond favorably to aeration when it is properly timed.
Both spring and fall are ideal times to aerate cool season turfgrass such as Kentucky bluegrass and perennial ryegrass. In most cases, spring aeration is performed between March and May. Fall aeration is done in late summer and early fall, usually between mid-August and late November. Aeration before or at the time of late season fertilization enhances root growth responses and improves spring green-up and growth.
Although aeration is beneficial for lawns, it also can open up spaces for weeds such as crabgrass and annual bluegrass to invade the lawn. It is best to aerate and seed before you apply pre-emergence herbicides like Corn Gluten. If you wish to aerate and utilize corn gluten, you should wait until the fall for aeration once any crabgrass has past its’ chance to germinate. Applying fertilizer after aeration helps the lawn compete against weeds. Water the lawn after aeration, particularly in areas where drought and high temperatures are common.
What Can you Expect?
Immediately after aeration, your lawn will be dotted with small plugs pulled from the soil. Within a week or two, these plugs of thatch and soil break apart and disappear into the lawn.
About 7 to 10 days after aeration, the aerification holes will be filled with white, actively growing roots. These roots are a sign that the turfgrass is responding to the additional oxygen, moisture and nutrients in the soil from the aeration process.
On compacted soils and on lawns with slopes, you should see an immediate difference in water puddling and runoff after irrigation or rainfall. After aeration, your lawn should be able to go longer between watering’s, without showing signs of wilt. With repeat aeration’s over time, your lawn will show enhanced heat and drought stress tolerance.
Don’t expect miracles from a single aeration, particularly on lawns growing on extremely poor soils. Most lawns benefit from annual aeration. Lawns that receive this care will be healthier, more vigorous, easier to maintain and have fewer pest problems than lawns that are neglected.