Building a window box is an easy DIY project that is great for any beginner. The best choice of wood for a window box is cedar or cypruss, because both woods will naturally resist rotting the best. This will give your window box the best chance of lasting more than five years. The process of building a window box begins with measuring the window for window box length, followed by assembly, followed lastly by hanging it. Let's skip straight to the middle and focus in on the actual building of a window box and the steps that are required. You'll need a drill, a few special bits, a brad gun, and a miter saw for this project.

For simplicity purposes let's build a 36" window box from 3/4" thick cypruss. Cypruss wood stock can be attained from most local lumberyards in a variety of dimensions. For window box purposes, a 1" x 8" board is recommended. For this box we will need roughly 12 feet of length. Now, miter the board at 34.5" three consecutive times such that you have three boards, one for the bottom, front, and back. We want to join these three boards with screws so that the boards are held tightly together. Butt two boards up at a ninety degree angle and join them with some gorilla wood glue. You want to make sure you use a wood glue designed for exterior purposes. Once glued, shoot a few brad nails along the joint to hold the two boards together temporarily. Next, countersink three small holes through the boards in preparation to pass screws in to more securely join the boards in a ninety degree fashion. A countersink drill bit is one that drills a pilot hole deep and a big hole shallow so that the screw head can sink pass the face of the board. Countersink a hole on the left, in the middle, and on the right. Next, sink a screw into the boards so that they grab tightly. The butt joint should show on the bottom of the box. Repeat the same steps to fasten the back board to the bottom boards. Once finished, you will have everything but the side pieces.

For fastening of the side pieces I recommend again using gorilla glue and brad nails to quickly secure the piece to the box. Follow that up with countersunk holes and screws to secure the side pieces to the box firmly. The side piece should be cut to size first. Once the side pieces are attached, the structural assembly of the box is complete. Next, use a drill with a 1/4" drill bit to drill drain holes in the bottom. I recommend placing a hole in each corner of the box and one in the very center where water will likely migrate to the most. Next, caulk inside the box to seal all the inner joints. This will reinforce the box and also keep water from seeping through. Lastly, staple an erosion tarp to the inside of the box. This will act as a filter between dirt and water so that water can drain through the box easily while keeping the dirt in. Viola, now you're ready to hang it and put flowers in it. It's just that easy. If you're not up for the challenge of building a wooden window box every five years, a good idea may be to consider investing in a PVC window box. They're moisture resistant, reasonably priced, and because they don't rot they're designed to last 30 years and more without any maintenance.