I have a few areas of my lawn that I have had trouble growing grass in. I can't figure out why. I have aerated these areas each year with the rest of my lawn, I have even tilled it and added new soil to the area. For some reason these areas still become very hard for most of the year, even though they are irrigated with the rest of my lawn. At this point I have gotten pretty frustrated as all I have been able to do is shrink these areas. Any recommendations?