If you have a healthy lawn you will have a healthy population of earthworms. Earthworms provide a natural fertilizer for your soil and their diet consists of plant litter, soil and organic matter. Earthworms also improve the aeration of your soil and help with thatch decomposition.
Before planting your new lawn, determine your soil type. There are three basic types of soil, sandy, loamy and clay. These three basic types of soil can also be found in combination.