Grass roots need oxygen to function, and with heavy clay soils in much of the Midwest, getting enough oxygen to the roots can be difficult. With Core Aeration, we poke holes into your soil and pull the cores out. Aeration helps lawns with thatch problems. It loosens the soil to let nutrients work better; plus, it helps your lawn make the best use of watering because an aerated lawn will retain more water with less runoff. You do not want to aerate in the Summer, however. It is best to wait until the cooler weather, Spring or Fall, arrives and the soil is a bit more moist.