Backyard grass is soft, but should not be spongy. Spongy yards contain a high level of thatch or built-up pieces of dead grass and other garden debris. If thatch becomes too thick, it prevents the grass from obtaining soil nutrients. For proper lawn maintenance, de-thatch your yard every two years.
Mow the lawn to half of its normal height. Remember to do this slowly, in 1/4-inch intervals to avoid shocking the yard. Wait two days in between the mowing rounds.
Rake the yard thoroughly with a thatcher. A thatcher is a bladed rake with hooks on the ends to tear out the thatch. Rake up the thatch pieces from the yard and dispose of them.
Sprinkle the entire yard with a seed blend designed for your type of yard.
Fertilize the entire yard with a fertilizer/pre-emergent crab grass killer blend.
Water the fertilizer in thoroughly. For best results, irrigate the yard with an inch of water and let it soak in completely. Repeat this process twice a week during the duration of the grass' growing season.