Two main aerating tools exist — a spike aerator and a plug aerator. With a spike aerator, you simply use the tool to poke holes into the ground with a solid tine, or fork. Plug aerators remove a core or plug of grass and soil from the lawn. For the best results, use an aerating tool or machine that actually removes plugs of soil. Poking holes is less effective and can actually cause additional compaction in the areas around the holes.
Look for an aerating tool or machine that removes soil plugs approximately 2 — 3 inches deep and 0.5 — 0.75 inches in diameter, and about 2 — 3 inches apart. These machines can be rented from lawn and garden stores or home improvement centers. Always follow the directions provided by the store. You may want to consider sharing the rental cost with a neighbor who is interested in aerating the lawn.