I was rather surprised that we have never published a plan for a window box planter. This is a terrific project that does wonders to dress up a home. Adding window boxes, with the right plantings, can turn a house from boring into sophisticated and classic. A flowering window box gives a home a much more rich feel that a house without.
I made a similar window box about 10 years ago for a craftsman style home that we had. We drove by the house recently and they are still hanging today. I made mine from Western Red Cedar and was careful to make the dimension just right for an off the shelf (inexpensive) plastic planter. This kept the moisture from getting to the wood and allowed for an easy swap out to be sure each planter was receiving a chance at optimal sunlight.
You will find the full plans along with a video, plan diagram, and cutting list by clicking on the picture. Just in case the PDF plans move, we have local copies here:
Good luck building your own planters.
Below is a picture (grainy as it is) of the window boxes that I built 10 years ago. A bit difficult to see, but I nostalgia forced me to include it nonetheless.