Topdressing is a method of adding compost or other materials to improve soil composition as well as to level out sections of the existing soil. This involves spreading a thin layer of compost and soil over the lawn, 1/2" to 1" thick. Large clumps of topdressing should be broken down for an even spread. In the Greater Toronto Area, leveling the soil to repair low spots is normally done with loam or topsoil.
The benefits of topdressing are to feed the soil with essential nutrients and microbes that keeps your lawn healthy. This method allows an increase of microorganism activity that reduces the thatch layer in the lawn. Regular topdressing in the Durham Region can also help improve drainage in clay soils or moisture retention for sandy soils.
Topdressing works best after aerating or dethatching. This can be done either by hand or by machine. It is recommended that topdressing be done as long as the lawn is actively growing.