Peat moss is organic matter that contains decomposed plants--often sphagnum moss. Adding peat moss to the existing topsoil in a growing area will amend the soil and make it a higher quality soil. Peat moss is acidic, so adding peat moss will help to increase the acidic level of topsoil. Adding peat moss will also improve the soil drainage in a growing area.
Till the growing area to work the topsoil and break up the large chunks of soil. Set the tiller to till the soil to a depth of at least 4 inches.
Add a 1-inch layer of peat moss for every 4 inches of topsoil you have tilled. If you tilled only 4 inches of topsoil, add 1 inch of peat moss. If you tilled down to a depth of 8 inches, add 2 inches of peat moss. Spread the peat moss evenly over the entire surface of the soil.
Till the soil to incorporate the peat moss. Work the tiller over the entire growing area until the peat moss is fully incorporated.
Rake the surface of the soil smooth.