Planter boxes are a terrible idea.  Most homes that have these installed were done so without proper waterproofing and drainage barriers at the walls of the structure.  As you can see moisture can infiltrate the wall and flooring structure and as a result causing damage to the structure.  Repairs can be very expensive as the garden box will need to be removed, the exterior cladding removed and any wet or damaged framing will need to be replaced.  This will involve removing the finished interior wall sheathing and flooring as well to install new framing, electrical, etc.  Moisture in wall causes mold growth and that in itself is a health hazard.