Provide drainage while keeping large pots light: Cut dollar store pool noodles and use as drainage material instead of stones. Large planters will be light enough to move later if needed.(and could use styrofoam peanuts for smaller pots)
Hydrangea paniculata Limelight, large white blooms tinged with pale green; trailing Ivy at the base spills over the sides of the classy zinc planter boxes. Baltic Ivy (variegated creamy edge) would combine well too.