Lawn Age

• Do not aerate newly sodded or developing, young lawns started from seed, plugs or sprigs. Aeration is disruptive to lawn grass roots and, if plants are tender or not well-established, the puncturing tines may do more harm than good. Withhold any aeration activities until the following year after the lawn has established and filled in as a dense, green carpet with deep roots.
  
  

Time of Year

• Lawn aeration needs to be conducted at the proper time of year based on the turf grass type. Always aerate at the beginning of the lawn's active growing season and after it's been mowed at least two times. Cool-season lawns, such as those with fescue or bluegrass, need to be aerated in the fall or early spring. Do not aerate in summer's heat or during droughts. Conversely, warm-season lawns -- those with zoysia, St. Augustine or Bermuda grasses -- need to be aerated in late spring after they green up, after temperatures warm and grow vigorously. Don't aerate in fall or winter when they're dormant. Contact your local county cooperative extension office to learn about ideal aeration timing in your region's climate and considering various lawn grass types.
  
  

Condition of Lawn

• If your lawn is healthy and there is no more than 1/2 inch of natural thatch build-up, aeration likely isn't necessary. Some thatch -- the decaying clippings that fall on the lawn after mowing -- is beneficial for the lawn as it provides nitrogen and shades the soil to help retain soil moisture. Also, if you have earthworms in the soil under your lawn, chances are the soil is naturally porous and in balance, so hold off on aeration.
  
  

Rainfall Considerations

• While lawn aeration helps to alleviate soil compaction and improve drainage of water, do not aerate when the soil is wet or bone-dry. If it's a rainy weather pattern, hold off aerating until the lawn is not muddy or flooded. The ideal soil condition is moist. Likewise, if you're in a drought, irrigate the lawn one to two days in advance of aeration. The deep watering softens the soil for coring and the soil moisture benefits the grass roots. Consider postponing aeration if it's so dry that there are watering restrictions. The aeration doesn't benefit the turf if it can't grow with appropriate moisture afterward.