On the subject of the hedge, I had a couple of plant ideas for the curvy bed that C has recently re-exposed. Perhaps we should investigate mosses? Scotch moss likes shade and even flowers part of the year.
Then again, nix mosses — an ornamental grass would be a more appropriate scale for the giant hedges. Japanese Forest Grass (otherwise known as Hakonechloa macra ) is perennial, likes shade, goes well with hostas, and comes in a a number of varieties (Albostriata, All Gold and Aureola, to name a few). I just read about a new variety “Beni Kaze” that turns bright red in the fall, but have not been able to find any pictures. From my cursory internet research, it seems highly sought after and probably a bit spendier than its cousins.