Aerating your lawn breaks through the thatch layer, enables the roots to breathe, and improves water and nutrient penetration. The process also helps break down thatch by providing a better habitat for the microorganisms that do those sorts of things. Aerating annually, in late summer or early fall, is one of the best things you can do for your lawn, thatch or no thatch.

Signs that your lawn needs to be aerated include

• Worn areas where people walk often
• Water puddles after irrigating
• Water runs off the lawn after only a few minutes of watering
• Parts of the lawn that just can't seem to keep moist

The most effective type of aerating is with a gas-powered machine called a core aerator that pulls out small cores (or plugs) of grass and soil. Other aerators use short spikes to punch holes in the turf. Spiking isn't nearly as effective as core aerating, but it's better than nothing. You can find aerators at your local tool-rental center.

When you aerate, strive for an even 3- to 4-inch spacing between holes throughout the lawn. To do so, you must make two passes in different directions. Make sure that the soil is slightly moist — not too wet or too dry. Set the aerator to pull out cores that are about 3 inches long, which end up all over the lawn. Rake up the cores if they bother you; however, if you leave them, the cores break down quickly and the nutrients return to the lawn. After aerating, water and fertilize the lawn.