Ann: maybe this will help
For the Latest Gardening Trend, Think Outside the (Flower) Box
You will have to either sit in a shelf or attach with brackets. I would think it is the same as exterior except for mounting.
Hi Ann: It would be just like an outside window box. You just need to be able to put it in the right light requirement for your plants. Line the box with a plastic planter so that you don't get drips on your window sill or floor. Good luck
Hi Ann, are you looking for a wooden flower box that will mount to the wall under a window in the house? If so, it will get very heavy when you water the plants. You'll want to make sure that it's properly anchored to the wall, so it won't rip away from the sheetrock.
If you're talking about a pretty box for flowers that you set on the table here's a post: https://www.hometalk.com/28277689/diy-silver-flower-box
2 x length of box required and 2 x width of box required + 1 base for box. You can either Glue and nail or screw the box together. Set up on short legs. 2 x pieces of timber across base - inset!. if required. Drainage holes if required. Finish to suit application......Have fun!
Hi Ann, here is a great project that shows how to build one... https://www.hometalk.com/40027935/rustic-wood-box