There are a number of different reasons that the grass in a lawn may die, and it can be frustratingly difficult to determine the cause. While a number of diseases can kill a lawn, it's often best to consider non-disease causes first. Your grass might be getting too much or too little water, or the soil might be too compacted.
Water is essential to the health of your lawn, but it can also be the cause of your lawn dying. If you water your lawn too often, you risk killing it. As a general rule, it is best to water enough to wet the whole root zone on an infrequent basis. If your lawn is healthy and your soil is not compacted, give your lawn about 0.75 to 1 inch (1.90 to 2.54 cm) of water once a week. As summer temperatures taper off to cooler weather, it’s best to water less often.
Soil compaction can also hurt your lawn. It is important to till the grass adequately before it is established. Too often, people add just a couple of inches (5 cm or so) of soil before they seed or sod. Unfortunately, handling your lawn in this manner will lead to a shallow root system. Instead, it is best to till to a depth of 6 to 8 inches (15.23 to 20.32 cm) before you plant.
To help deal with compaction and prevent the demise of your lawn, don’t forget to aerate as needed. When you aerate your lawn, be sure to cover about 15% of the area with holes. Though this procedure can be tedious, it can go a long way toward saving you the disappointment of having to deal with your lawn dying before you eyes.
Other things that may lead to lawn problems include improper mowing heights, thatch that is too thick, slopes or low areas, certain herbicides, insects, and diseases. If you believe a disease may be the cause of your lawn dying, take steps to identify the problem and correct it quickly. There are many resources online that may be help you recognize diseases and other lawn conditions. If such resources fail to help and your lawn is still dying, consider seeking the services of a lawn-care professional. Keep in mind that many diseases are caused by improper lawn care, so it's important to take excellent care of your grass.