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What is lawn aeration, and what does core aeration include?
Core aeration pulls plugs of soil out of the lawn with hollow tines and drops them on top, so air and water get past a compacted surface to the roots. Spike aeration presses holes without removing soil, and University of Maryland Extension says it adds to compaction. UMD describes plugs 2 to 4 inches deep and ½ to ¾ inch wide, 2 to 6 inches apart. Ask which machine the crew runs and how many passes the price includes.
When should you aerate your lawn?
While the grass is actively growing, never when it is dormant. For cool-season lawns such as tall fescue and Kentucky bluegrass, UMD's advice is once a year in autumn, just before overseeding, where the lawn gets regular foot traffic, and every 2 to 3 years otherwise. Warm-season grasses such as zoysia and bermuda grow in summer, so they get aerated then.
If it has been dry, water the lawn first; UMD notes the tines cut into moist soil more easily. Don't aerate soggy ground either, since wet soil compacts under the machine's weight and your feet.
Does aeration help the lawn?
Where the soil is compacted, yes. UMD says a compacted layer as thin as ¼ to ½ inch at the surface slows drainage and makes dry soil harder to re-wet. Core holes open channels for air and water and give seed a place to land. Cars, foot traffic and pets cause it, and clay packs faster than sand, so the dog run and the path to the shed need it more than the front lawn.
Aeration doesn't fix standing water. UMD says aeration alone can't solve soil saturation, so a spot that stays soggy for days after rain needs its drainage looked at. Ask where the water comes from and where it could go.
Should I overseed after aerating?
On a thin cool-season lawn, yes: aerate, then seed right after so the seed drops into the holes and the loosened soil. That is why UMD puts the yearly aeration just before autumn seeding. Its guide says warm-season lawns such as zoysia and bermuda are not overseeded, so ask why if a quote adds seed to one.
Seed is its own line on the quote: the mix, the pounds per 1,000 square feet and who waters afterward. If one quote covers core aeration of the front and back lawn and another adds overseeding with a named seed mix, ask the first for its seeding price, or the second for aeration alone, before you compare.
What should an aeration quote list?
The lawn area in square feet or the lot size, core (hollow-tine) aeration, the number of passes, and anything bundled with it, such as seed, fertilizer, lime or topdressing, each on its own line. UMD notes that more than one pass is sometimes needed to make enough holes, and University of Minnesota Extension recommends three to five passes with a commercial aerifier on compacted soil before seeding.
Before the crew arrives, flag sprinkler heads, shallow irrigation lines and buried dog-fence wire; a tine through any of them is a repair bill. If the lawn is on a mowing plan, ask whether aeration is a one-time charge or added to the monthly price.
Frequently asked questions
Should I pick up the plugs after aeration?
No. Leave them on the lawn. UMD says the plugs break down in a couple of weeks, putting the soil back on the surface.
Is aeration the same as dethatching?
No. Dethatching rakes out thatch, the layer of dead and living stems and roots between the soil and the grass blades. UMD calls a ¼ to ½ inch layer healthy and 1 inch or more a problem. Zoysia, bermuda and Kentucky bluegrass build it up; fescues rarely need it removed.
Can you aerate in the spring?
Yes. Cool-season grass grows in spring too, so aeration works then. If you are also seeding, fall is the better time: University of Minnesota Extension's preferred overseeding window is mid-August to mid-September, with early spring second best.
Sources
- University of Maryland Extension: Maintaining an established lawn · Checked
Core plug size and spacing, solid-tine compaction, timing and frequency, saturation, thatch depth and overseeding.
- University of Minnesota Extension: Renovating a lawn · Checked
Aerifier passes on compacted soil and the overseeding window.
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