Dethatching is a term to describe the removal of debris that is compacted and accumulated on the soil surface of the turf or lawn. The procedure pulls plugs of thatch debris out, leaving the lawn in a ragged state ready for re-growth. Dethatching forces the lawn to grow buds near the stems, reducing the amount of thatch build up in the future. The best time to dethatch is in the spring and should be done every 1-2 years.
Mow lawn to a length that is half the normal mowing height.
Rent or purchase a power dethatcher. The unit looks similar to a lawn mower except the blade moves in a vertical motion instead of horizontal.
Set the blade depth and spacing to the appropriate level for your lawn. Rental companies will assist with this calibration. The blade is generally set to cut ¼ to ½ inch into the ground. This level will pull up the thatch debris and stir up the soil surface. The blade spacing is set at 1-2 inches apart for tough and dense grasses like Bermuda grass and 3 inches apart for thinner grasses.
Start dethatching the lawn by moving in a parallel direction followed by a second pass in a cross direction. Check the thatch depth and width after the first several feet and make adjustments if necessary.
Thatch that is over 1 inch thick requires a third pass at a 45-degree angle from the first two passes for full penetration of the thatch.
Rake the lawn when finished to remove the debris that was pulled up by the dethatcher. The machine pulls the debris out but does not remove it.
Re-seed the lawn at this time, if desired. Spread grass seed on the lawn and rake into the open soil. Cover with a light covering of organic matter to hold the seed in place.
Add lawn fertilizer to the entire dethatched area and soak with water to promote root production of both the current grass and new seed. Fertilizer and water is recommended with or without re-seeding.