Flower boxes are a form of container gardening that add depth and dimension to any area they are placed. Patio flower boxes can contain seasonal flowers, annuals or perennials to accentuate the patio and add a splash of color to the surrounding landscape. These can be mounted on a patio as a permanent fixture, placed on a side so they can be relocated easily or hung to create visual interest at varying levels.
Measure the area on your patio where you want to display the flower box so you can determine the height, length and depth. Keep it 3 feet wide so you can access the flowers planted in the middle with ease. A depth of 8 to 10 inches is sufficient to provide roots of most flowers ample space to spread and grow.
Use a circular saw to cut the boards to size, or have a professional cut them for you. You will need two long boards for the front and back of the flower box, two short boards for the sides, and a base board that is as long as the front and back piece, but as wide as the side.
Place the five boards on a flat and even surface in front of you.
Take the front board and hold one of the short pieces on its side, ensuring the edges are flush, and the tops are even with one another. Wear your protective eyeglasses and earplugs and drill two 1-inch galvanized woodscrews into the front piece, an inch from the top and bottom edge. These screws will penetrate the front of the flower box and the side piece to join them both together. Reinforce the joint by drilling another screw in the center, if necessary. Set this L-shaped frame aside.
Repeat the procedure to connect the back piece to the second short side.
Join the L-shaped frames together by drilling woodscrews into them in such a way that the short end of one frame attaches to the long side of another. Your flower box will now resemble a box without a base or lid.
Turn the flower box upside-down. Take the base piece and drill 3/4- to 1-inch drainage holes, evenly spaced throughout its surface. Carefully lower it into the cavity and attach it in place by drilling three woodscrews per long side and two per short side.
Sand the flower box to remove any sharp or rough edges. Paint it a bright color, or apply a coat of clear paint to protect it from natural elements that cause wear and tear.