Does anyone do that you can you only use them with sash windows? Thanks!!
I had casement windows. I attached the window boxes myself. It's hard to find something that will fit them otherwise.
I'm sure they make some kind of bracket that might fit. But I just used that metal 'tape' with the holes in it. I wrapped the tape around the windowbox and then attached the tape to the bottom part of the windowsill with screws. I painted the metal to match the box.
You need the box to be low so the window doesn't hit it when open.