The Dethatching Process
Check for excessive thatch - that's the thick mat of clippings, cuttings and stems that builds up between the green blades and the soil surface. Get down on your knees and part the grass with your hands to see if it's built up to more than an inch.
Understand how de-thatching works: When air, water and light cannot reach the soil surface any longer because of thick thatch, you have to rip it out. The lawn looks rough for a while, but soon you'll see healthy new grass shoots taking off.
Start by really raking the grass with a stiff-tined garden rake or a de-thatching rake. Work up a sweat - sink the tines into the thatch and pull out as much as you can without pulling up the grass.
Can't see the ground even after vigorous raking? Try using a de-thatching blade if your mower has one, or rent a de-thatcher from a reliable dealer who can brief you on its safe operation.
Water the lawn the day before de-thatching only if it's very dry. Begin running the de-thatcher at the farthest point from your home so you can master it before hitting the high-traffic areas.
Watch what you're doing - keep the de-thatching blades on target to cut through the debris without scraping the soil surface. Run the machine over each swath of lawn only once.
Use a leaf rake to clean up the messy piles of thatch you've removed. Recycle all of it in your compost pile.