Planting Under Oak Trees

Please tell me what can grow under a big oak tree. The soil is shallow and much limestone in the area… grass doesn’t grow. Is there a tall perennial flower? Or ground cover with flowers?…

Planting perennials in root bound soil

I have a small back yard that is surrounded by lots of trees. Even perennials such as hosta are doing poorly. Do you recommend that I plant them in pots in the soil with room for the roots to grow…