Whether an unsightly patch or a thick layer that keeps air, water and light away from grass crowns and roots, dead grass doesn’t belong on a healthy lawn. Dead grass on an existing lawn can be the result of a number of causes, and its removal should address only the specific problem because you don't want to have to reseed the entire lawn.
Rake the lawn with a fan-shaped broom rake in the spring after the snow has melted and the ground is firm. Debris from this step can go onto the compost pile. Diagnose your dead-grass problem before going further. Winter kill from snow mold requires a much less extreme treatment than botrytis blight or excessive thatch.
Remove patches of winter-killed or dog-damaged grass with a rigid-tined garden rake. If only the dead grass pulls away, all you need to do is over-seed thin areas. If all of the grass pulls away like a toupee, get the soil tested for fungus or viruses before reseeding.
Rent a core aerator to break up thick layers of thatch or lawns that have compacted soil. Core aerators are heavy machines that operate like lawn mowers; aerate one way and then run the machine at right angles to the original lines for complete coverage. Aerating punches hundreds of small holes in the surface for air and water to get to grass roots.
Use a thatching rake, called a power rake, to pull thatch out of the lawn. Thatch rakes have hooked, sharp steel tines that cut, or “scarify” the ground as they pull all of the dead grass out of the lawn. Thatching strips the dead grass that protects grass roots as well as destroying grass crowns; reseeding is often necessary.
Water your lawn well afterward, no matter what method you use to remove dead grass. It stimulates roots and helps undo the damage done by thatching.