The answer to 'when to aeration' is that the best time to aerate your lawn is in the fall, typically between September and November. Aerating your lawn helps to improve soil compaction, promote deeper root growth, and allow better water and nutrient absorption for your grass. This is an important maintenance task that should be done every 1-2 years, depending on the condition of your lawn.
Aerating your lawn in the fall allows the grass to recover and establish new roots before the winter dormancy period. This helps your lawn come back stronger and healthier in the spring. Aerating in the spring or summer can be done, but the grass may not have enough time to fully recover before the hot, dry summer months.