A safe general rule for time of is to aerate only when the desirable grasses are growing vigorously. You have to worry about proper fertilization schedules, the right amount of watering, proper soil drainage and much more. However, one of the most important considerations here is soil aeration. Aerating a lawn offers numerous benefits, and will help ensure better health and growth for your grass. AMES, Iowa – Aeration is an important part of lawn care, but take care to aerate properly and at the correct time of the year. Here are some tips from Iowa State University Extension and Outreach horticulturists on the proper way to aerate a yard.