Contributed photo.

September and April are the recommended times to aerate lawns in Iowa, according to horticulturists with Iowa State University Extension and Outreach. Aeration relieves soil compaction, improves water and nutrient movement, and prevents thatch accumulation. It improves growing conditions, resulting in healthier lawns. Aerating in September or April provides time for the grass to recover during favorable growing conditions. The horticulturists advise, the frequency of aeration depends on the soil type and amount of use for each lawn. Those in clay soils should be aerated twice each year, while annually should suffice for established, well-drained soils.