You may envision a country cottage when you think of window flower boxes, but they can be a good addition to any house style. When painting or decorating your window boxes, just keep the structure architecture and surrounding garden style in mind. For a modern or traditional home, paint the window boxes a single color, matching the house trim. If you have a country home and garden, you may add stenciling or free-hand painting for decoration to the outside of the widow flower boxes. Of course, simply brushing the boxes with a stain will go with any style home. To complete this project you will need basic carpentry tools and skills.
Determine the length of the window box. Consider your window before deciding on a short or long window box.
Cut two boards for the window box's length and width. At least a 12-inch width is preferable, but no less than 8 inches.
Make a frame with the four boards. Fit the two shorter boards inside the two longer boards at both ends. You will have one smooth surface on the front and back of the box. Use three screws going into the outside of the long board and into the side edges of the shorter boards; use a drill with a screwdriver attachment. Repeat this process for each corner. You now have completed the frame.
Measure the bottom of the frame, both length and width. Cut a piece of plywood at this measurement.
Place the plywood on top of the wood frame. Screw through the plywood and into the bottom of the boards. Place your screws about every 5 inches, all the way around. The box is now complete.
Drill several water-drainage holes through the plywood. If you don't provide drainage holes, the water will puddle at the roots, causing unhealthy plants.
Turn the window flower box right side up, so the plywood is at the bottom. Screw in eye hooks along the top of the back long board. Place one at each end and then space the rest approximately 6 inches apart. Use heavy-duty open metal hooks (found at hardware stores) to screw into your outside window frame at the same intervals as your window box.
Sand the flower box smooth and then wipe the dust off with a soft cloth. Use exterior paint, wood stain or sealer to cover the wood, as you prefer.