Simply put, lawn aerification is the process of introducing air (oxygen) into your soil. Overtime, soil becomes compacted due to an abundance of organic material laying on the surface. This excess material is called thatch, and is composed of dead leaves, old grass clippings, and other organic matter. The combination of soil compaction and thatch will slowly suffocate the grass making it unhealthy, patchy, and brown.
There are several types of aerification, but the most responsive type of aeration is core aerification. Small ‘cores’ of turf will be removed, creating spaces in which oxygen, water, and other nutrients will be able to freely reach the soil and the root system of your lawn.
Late fall is the best time to aerate. Follow the aerification up with a slow feed fertilizer and over-seeding and your lawn will be lush, healthy, and beautiful when spring rolls back around.