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.
There are so many uses for shelf brackets! These are shelf brackets, repurposed to frame a window --- what a clever idea. You could do this to define and separate spaces in the same room, too. (Say an entryway and a dining room.