Leave the clippings on the lawn when mowing. This provides nitrogen for the lawn. Mow frequently so that no more than 1/3 of the length of the grass blade is cut in any one mowing. Grass decomposes rapidly and very little thatch is formed. Small amounts of thatch can actually be beneficial to a lawn, serving as a mulch. Many parks and golf courses have been doing this for years. Other uses for grass clippings include mulching for weed control and as a great addition to your compost pile. There are some cities that no longer will allow grass clippings in their dumps.