In lawns where they appear, moss and toadstools go hand-in-hand. Moss is a simple plant with no roots and short growth. Moss typically grows in a dense mat-like colony. It does not crowd out grass, but instead grows in areas where grass is thin and patchy. Unless they are part of a fairy ring, toadstools are actually a part of a beneficial cycle of lawn care.
Toadstools grow as part of the reproductive cycle for underground fungi that break up organic material. Fairy rings, on the other hand, occur when soil is compacted and water cannot penetrate. To kill moss and toadstools in your lawn, improve the soil conditions.
Mow your lawn with a lawn mower that bags all the grass and debris that the mower cuts. This will help to remove toadstools and bring grass down to manageable levels for the rest of the process.
Rent a dethatching machine and soil aerator from your local hardware or large machinery store. Both a soil aerator and dethatching machine operate similar to a push mower.
Dethatch your lawn with the dethatching machine by setting the level of the dethatching blade. Push the machine over your lawn in sections similar to if you were mowing. The dethatching machine will remove thatch and fungus that causes toadstools, as well as low-growing moss.
Loosen soil with a soil aerator by setting the depth that the aerator will areate to. A soil aerator aerates the soil by removing plugs of soil and sod from the ground, allowing water and nutrients to penetrate the lawn. Once you have set the depth of the machine, pass it over the lawn in sections similar to the way in which you mow the lawn.
Spread soil amendments such as compost and gypsum as well as a balanced 10-10-10 fertilizer over the lawn to a depth of 2 inches.
Work amendments into the soil level through the grass by combing grass with a leaf rake.
Water your lawn to work these amendments into the soil through the aeration holes. Gypsum will help to break up compact soil, while fertilizer and compost will provide nutrients that support the healthy development of grass.
Overseed lawn with grass seed to fill in patchy areas of the lawn. Continue to water lawn every few days to germinate seeds. Then slowly back off your watering schedule to once weekly.