When to Aerate Your Lawn: Fall vs. Spring by Grass Type
Core aeration pulls thousands of small plugs of soil out of the lawn. The holes let air, water and fertilizer reach the roots, relieve compacted soil and help break down thatch. It works best when the grass is growing strongly enough to fill the holes within a few weeks, so the right time depends on your grass type.
The short answer
| Grass type | Best time to aerate | Soil temperature |
|---|---|---|
| Cool-season (tall fescue, Kentucky bluegrass, ryegrass) | Early fall; early spring is second best | Cooling through the 60s in fall |
| Warm-season (Bermuda, zoysia, St. Augustine, centipede) | Late spring to early summer, after full green-up | Holding above 65°F |
Not sure which grass you have? See cool-season vs. warm-season grass.
Cool-season lawns: early fall
Early fall is the best time for the same reasons it’s the best time to seed: warm soil, cooler air and fewer weeds competing for the open soil. Aerating right before you overseed puts seed in direct contact with soil, which matters more than anything else for how well it comes up. Finish at least four weeks before your first fall frost so the grass can recover.
Spring aeration works too, with two cautions. Wait until the lawn is actively growing and the soil has dried out enough to work. And aerate before you put down crabgrass preventer, not after: punching holes through the preventer layer can let weeds through.
Warm-season lawns: late spring to early summer
Bermuda, zoysia, St. Augustine and centipede recover fastest in the heat. Aerate once the lawn has fully greened up and the soil holds above 65°F, typically from late spring into early summer, and at least a month before growth slows in fall. Avoid aerating warm-season grass in fall: the holes stay open through dormancy and give winter weeds a place to start.
Do you need it?
Not every lawn needs aeration every year. Signs that yours does:
- A screwdriver is hard to push into moist soil.
- Water puddles or runs off instead of soaking in.
- Thatch, the spongy layer between the grass and the soil, is thicker than half an inch.
- The lawn gets heavy foot traffic, sits on clay soil, or was laid over soil compacted during construction.
Lawns on sandy soil with light use may only need it every few years.
How to do it
- Water first. Aerate when the soil is moist but not soggy: the day after a good rain, or after about an inch of watering the day before. Dry soil is too hard for the tines to go in.
- Mark obstacles. Flag sprinkler heads, shallow irrigation lines and buried pet-fence wires.
- Use a core aerator, not a spike aerator. Hollow tines remove plugs; solid spikes just push soil aside and can add to compaction. Aim for plugs 2 to 3 inches deep and 2 to 4 inches apart. On badly compacted lawns, make a second pass at an angle to the first.
- Leave the plugs. They break down within a couple of weeks of rain and mowing and return soil to the surface.
After aerating
- Cool-season lawns: overseed right away, and feed according to your fertilizer schedule.
- Warm-season lawns: keep up normal watering and feeding while the grass fills in.
Keep the lawn watered for the next two weeks; the holes close fastest when the grass is growing hard.
Check your timing
The ZIP code tool shows today’s estimated soil temperature for your lawn and which jobs are open right now.