The whole window will have a one foot wide window sill. I will have to show you the place to get a good idea of things. Basil planted in teacups for the kitchen, cheap and pretty teacups planted with fresh herbs on the window sill.
Maybe an up cycle idea for all those used formula tins - Tin can vertical plant hanger and rustic painted wooden screen door. Love the screen door as a decorative element with potted plants surrounding.