Garden planter boxes are generally made of lumber. They can be painted or left natural with a clear sealer painted on. This type of planter can be used for lawn edging, window boxes or as a decorative element dispersed throughout your garden. Planter boxes can even be used in the vegetable garden, as a raised bed. Adjust these instructions appropriately to build a garden planter box size that fits your needs.
Cut your lumber. You may use any type you like. However, both cedar and redwood are naturally weather resistant and durable. Cut two board lengths of 1 foot and two board lengths of 3 feet.
Screw the ends (shorter pieces) to the sides (longer pieces). Place the side pieces over the end pieces and screw in three screws at the corners of each of the side boards. Use galvanized screws, as they are resistant to rusting.
Place the constructed wood frame onto a piece of plywood. Trace around the frame. Cut the plywood. This will form the bottom of your garden planter box.
Place the cut piece of plywood over the top of the wood frame (the top and bottom are the same). Screw the bottom onto the frame. Use four screws along each side and three screws on each end. Make sure you are catching the wood frame with the screws.
Paint your garden planter box with an exterior paint or a clear sealer, inside and out. Use an organic sealant if you will be planting vegetables in your planter. Let the box cure overnight, before planting in it.