Throwing any old fertilizer on your lawn is a great way to not only destroy the lawn, but to help contaminate your local river or lake as well. Fertilizers are only meant to supplement the nutrients already in the soil, and any extra nutrients are simply wasted and washed away, like phosphorus, or can actually burn your grass, like nitrogen. A nearby university cooperative extension will be able to test your soil, for a small fee, and the results will include recommended fertilizers for growing grass.
Just as the right type of fertilizer is important, when you fertilize is equally important. The grass needs to be in a growing state, not a dormant state, for the fertilizer to have any effect. Late summer is the best time for fertilizing warm-season lawns, while late fall is the best time for cool-season grasses. An additional application in late spring or early summer is usually helpful, but never in the early spring, as the fertilizer will encourage too much blade grown, and not enough root growth.
While your lawn needs to be watered, too much will cause excessive topgrowth that will just result in more maintenance, and too little will result in a thin and brown lawn. To get the right amount of water on your grass, apply about an inch of water once a week. If you use a sprinkler, this will end up being between one and two hours per section. Water in the early morning to reduce loss to evaporation.
Always keep a sharp blade on your lawn mower, as a dull one will damage the grass that remains behind. Set the height on your mower so that you cut only the top 1/3 of the blade, as deeper cuts will damage the lawn. If you need to make the grass shorter, wait a few days and mow it down again. Only mow the lawn when the grass is completely dry.
Decaying organic matter is the main source of nutrient replenishment for your soil. By leaving your lawn cuttings on your grass, you actively add nutrients back to the soil and reducing the amount of fertilizer that you need. According to the Ohio State University Extension, leaving these clippings on your lawn reduces your fertilizer needs by up to 25 percent.