I recently read an article about thatch in lawns written by Terry Blackburn who has a company in England dealing with lawn care. Terry shared that core aeration is helpful in degrading thatch in lawns and also helps solve some of the causes of thatch. Terry goes on to say that core aerifying in conjunction with topdressing will generally help correct the reasons that thatch is accumulating. These processes will also help solve the problems of compaction and poor drainage. Terry recommends topdressing between 1/8 and 1/4 inch. The topdressing adds microorganisms to the soil which helps reduce thatch. For more on Terry’s thoughts check out this site www.lawnsurgeon.com .