To make a wooden flower box you need only basic carpentry skills, a few tools and five pieces of wood. Keep in mind that the best wood to use is one that is naturally durable and deteriorates at a slow rate, such as redwood or cedar. However, a flower box made from other available lumber can last for many years when it is sealed properly.
Cut the lumber to create a frame for the flower box. For a 2-foot long box, you will need to cut two 1-foot board lengths and two 2-foot board lengths with a skill or hand saw.
Stand up one of the 2-foot pieces on its longer edge with a flat surface facing you. Stand up a shorter piece so the boards make an L-shape, with the edge of the shorter piece flush with the flat surface of the longer piece.
Screw in three galvanized screws, evenly spaced (top, middle and bottom), along the flat surface of the longer board where it meets the edge of the shorter board.
Repeat Steps 2 and 3 for the other two boards. Fit the two L-shapes together, forming a frame. Repeat the same attachment (screw) process, as before, to form a complete frame. Galvanized screws will not rust; therefore, they are optimal for outdoor projects.
Set the wood frame onto a piece of plywood or pressed board. Draw around the frame with a pencil. Remove the frame. Use a saw to cut the board where you have marked it. This piece will be the bottom of the wooden flower box.
Put the cut plywood on top of the wood frame. Screw it to the frame along the edges. Use four or more screws along the long sides and three along the ends. Turn the piece right side up to view your completed flower box.
Seal your wooden flower box. If you prefer a natural look, paint a clear exterior polyurethane on the inside and outside of the box. If you would like a decorative appearance, paint the box with an exterior paint. You can jazz it up further by adding designs using stencils. Just make sure that you also use exterior paint for the artwork.