A flower box is a welcome addition to any home or garden. It adds dimension to the exterior of a house, sprucing up the space with a burst of color. Flower boxes can be placed practically anywhere -- on the patio or porch, on steps, or in the yard or garden. They can even be hung outside windows. Flower boxes can be appreciated by the home's occupants and passersby on the street. Although there are many different shapes and sizes available in home department stores, you can build one to match your house at less than half the price.
Determine the height, width and depth of the flower box. Using the measuring tape, measure the area where you want to display the flower box so you can build it to fit the spot. Flower boxes are typically square or rectangular. Keep in mind that a flower box wider than 3 or 4 feet will prevent you from reaching the flowers planted in the center easily.
Decide on the material for your flower box. Although you can use a variety of material, wood is preferred because of its natural appearance and ability to blend with the surroundings. You can select any wood you like, such as pine, teak, oak, cedar or redwood, but keep your budget in mind. You can also use plywood sheets, but avoid these for large flower boxes, as they can get heavy because of the amount of soil they contain.
You will need five boards -- two identical boards for the long sides, two identical boards for the short ends, and one base board as wide as the short end but the same length as a long side. Cut them yourself with a handsaw, or have them pre-cut at a hardware store.
Drill 1/2- to 1-inch holes, spaced 6 inches apart over the base board to encourage good drainage.
Hold a long side board on an even surface and place a short end board against it, making sure that the seams are flush. Check that both of the pieces are at the same level, and attach them together with 1 1/2-inch galvanized wood screws drilled near the top and bottom edge. You will have an L-shaped structure. Repeat the procedure to join the other long side and short end as well.
Join both the L-shaped structures by holding them in such a way that the short end of one is against the long side of the other. Drill 1 1/2-inch wood screws into them so they are firmly connected. Check the stability of the box, and reinforce any joint by drilling another woodscrew so it is secure.
Turn the box so its base-side faces upward and lower the base piece over it carefully. Drill three woodscrews on each long side, and two on each short side, so it is joined securely.
Sand the flower box with the medium grit sandpaper, and spray a coat of the exterior paint so it stands out.