Like most living things, plant roots — including those of turfgrass — need air, water and nutrients. Unfortunately, traffic on the grass — from feet and vehicle/equipment tires, even from lawn mowers — can compact the soil, squeezing out the spaces between soil particles and preventing the vital movement of air, water and nutrients down to the roots. But a compacted soil-surface layer even as thin as 1/4” or 1/2″ can prevent your lawn from growing its best.
Thankfully, correcting a compaction problem is relatively easy with aeration machines (also called aerators or aerifiers). Aerators push tines (spikes) down into the ground to open up the soil. Some aerators have solid tines, while others have hollow tines that pull up plugs of soil (called cores). The best aerators for lawns are those with hollow tines, since the solid tines can actually further compact the soil around them.
Some aerators are equipped with a bin or bag to collect the removed cores of soil as the machine moves. Other people just allow the cores to remain on the surface and then break down over time. Regardless, after aerating your lawn, it’s a great time to topdress (spread a thin layer) with either sand (for clay soils) or compost (for sandy soils) over the lawn and then brushing the material into the core holes.
In general, a lawn should be aerified each year at a time when the grass is actively growing and still has time to recuperate before its dormancy period. For warm-season grasses (like bermudagrass and zoysiagrass), that’s any time in summer. Cool-season grasses (fescue and bluegrass) go semi-dormant in summer, so the best time to aerate them is in fall (or early spring). Also, the soil should be somewhat moist — not soggy nor bone-dry.
Aerification machines vary in size — some are powered walk-behinds, while others are more like ride-on lawn mowers or even as large as a tractor. Although the smaller aerators are less expensive than the large ones used by sports turf managers and golf course superintendents, even the “lawn size” ones can be pricey. Instead, you can often find them available for rent at many home-improvement stores and lawn/garden centers. Or you can contract with a local landscaping or lawn-care service to perform the work for you. Either way, your lawn will be “repay” you after aeration by growing more beautifully!