Growing grass in clay soil
I have unsuccessfully been attempting to grow grass in my backyard for years. There are a few areas that are covered in some vegetation mostly weeds but the majority is just hard compacted clay. I have tried using one of those slicer machines that puts slits into the yard and seeds but nothing has stuck in those hard dirt/clay areas. I was considering tilling the area and mixing some topsoil into the whole yard. The time to seed is now, so I don't know what to do before attempting. Should I till the hard clay, I can barely stick a shovel in it, I don't see how anything will grow there without tilling it.