A common problem in urban and suburban lawns is the soil becoming too tightly packed together. Compacted soils can be the result of a nutrient imbalance, or frequent activity. Healthy soils have air pockets, which creates space for micro-organisms to thrive, and water to be absorbed. 

Aeration, or adding small holes to soil, is one of the best ways to fight compaction and create a healthier lawn ecosystem. It also helps incorporate soil amendments, like compost. 

How to tell if your soil is compacted

An easy trick to identify a compaction problem is to stick a screwdriver into your soil a few days after a rain. If you cannot easily stick the screwdriver into the soil, then your soil might need aeration.  (We also recommend  getting a soil test, because this issue might also be from high amounts of magnesium, and aeration alone won’t solve the problem.)

Aerator by Aigarsr, 123RFA core aerator.  Photo by aigarsr, 123RF

​How to aerate

Aeration is best done with a core aerator, which pulls out plugs of soil that look like big Tootsie Rolls. There are some hand tools that you can use in a small area to create the plugs, but it’s best done with a machine, and worth asking a lawn company to do for you. Avoid using a spike aerator when possible—these tools simple push a hole into the soil and can increase compaction.

Tip #1:  Ask a lawn care company to core aerate when your soils are compacted. You can also rent a core aerator from a home improvement store. (Team up with your neighbors to maximize the rental and save money.)

How to Aerate and Overseed

When to aerate

Aeration is best done in the spring or fall, and after a deep watering or heavy rain. Even a machine has a hard time working on dry soil.

When transitioning from a chemical lawn to an organic lawn, you might consider aerating in both the spring and fall for a year or two. Don’t aerate repeatedly, though, as aeration can cut up important fungal connections in the soil.

Check your soil conditions each year to determine if soils are getting compacted from lawn mowers or foot traffic.

After aerating is the best time to top dress with compost, add organic materials, and  overseed .

Tip #2:   Add soil amendments after aeration for greatest results.