I have a pine/fir/blue spruce tree (one of those...looks like a Christmas tree) that we cut up about 7 foot to allow for walking under it a few months ago. It drops lots of little needles...and I think will be hard to grow grass under. Can I plant some type of ground covering flower or plant under it that requires little to no sun? I live in central Illinois, zone 5. Or is it just impossible to plant because of all the needles? I could use some wood to build a square around it and sort of "raise" the ground up with fresh soil about 6 inches, but will it inevitably fail? Thanks!