Over time, grass and soil can become compressed and compacted. This creates thatch, which is a thin layer of dead and living grass roots, stems and shoots that forms between the soil and the grass in your lawn.  Some of this organic matter, including the grass stems and roots, decays slowly, so thatch can build up.

As the thatch becomes thicker, it prevents air, water and fertilizer from reaching the roots of the grass. This causes your lawn to thin out and die. 

Aeration is the practice of making holes in your lawn to loosen the soil underneath. This lets oxygen, water and important nutrients reach the roots, so your grass can become lush, green and healthy. 

Aeration can also help improve a lawn growing in poor soil or heavy clay. 

Consider aerating your lawn if it is thin and brown and you have trouble growing grass. Aerating is also a good idea if your lawn is your grass is subject to heavy foot or vehicle traffic. 

The best time to aerate is during the growing season. Most homeowners should aerate their lawns at least every other year, while golf courses or other places that get heavy use are typically aerated at least twice a year.

Thoroughly water your lawn a day or two before you begin the aeration process.  Apply at least one inch of water. You can also aerate after a good, soaking rain that provides at least an inch of water.

After watering your grass, use irrigation flags to mark any areas in the lawn that might have hidden objects like tree stumps or irrigation heads. This will help you avoid running over them with the lawn aerator.

Whether you're using a core aerator or a spike aerator, go completely over the lawn in one direction and then go back over it in a perpendicular direction.

Spike aerators will punch holes in the lawn as you go, while core aerators will remove plugs of grass and soil. It's fine to leave the plugs on the lawn to decompose. 

Tip: A steel spike aerator is ideal for small yards, while a core aerator is designed to handle bigger areas.

Once you've finished aerating your lawn, apply grass seed, if needed, and fertilizer. 

Follow the directions on your fertilizer product for how much and how often to feed your grass. Water the lawn after fertilizing to avoid burning it.