I am in west central Wisconsin zn 4/5. I have an east facing terrace/boulevard under a Norway maple (separated by the sidewalk). I would like to plant daffs and tulips there then use hardy geranium/cranesbill as a ground cover so I don't have to mow that area. My concern is that the geranium will starve the bulbs of light and nutrients. It gets quite a bit of morning sun. Has anyone tried this?