Planter boxes give both amateur gardeners and container gardening enthusiasts an excellent option for showcasing an assortment of vegetables, herbs and flowers. According to Virginia Cooperative Extension, cedar provides an ideal material for planter boxes, since it is one of the most naturally rot-resistant wood species available for this type of carpentry project. Whether you place your 12-inch-by-11-inch cedar planter boxes on your back patio, mount them on windowsills or use them to line your front sidewalk, they'll provide visual enjoyment throughout the growing season for you and your loved ones.
Drill eight to 10 holes in the 12-inch-square, 1-inch-thick cedar board to provide adequate moisture drainage for any plants that you place inside each planter box. Use a 5/8-inch bit to produce large holes.
Lay the base board flat on the ground. Position two of the 12-inch-by-13-inch cedar boards perpendicular to the ground and butt them against the base of your planter, placing them at right angles to each other. Allow one 13-inch-long board to overlap the end of the base board and bring it flush with the other side board to minimize water leakage along the side seams of your planter.
Nail the bottom of each side board to the base board, using one 1 ½-inch galvanized nail every 3 inches along the bottom length of each board. Nail the two side boards together along the height of their connecting sides in the same way. Repeat this entire construction process with the two remaining 12-inch-by-13-inch cedar boards on the opposite corner of the base board.
Push the ends of the two pairs of side boards together at the third and fourth corners, making sure they're flush before nailing them together at each corner with three more nails. You should now have a basic square framework for your cedar planter box.
Finish your cedar planter box by nailing the 1-inch-by-2-inch boards along the top edge. Fit the edging boards in place around the top perimeter of your planter, placing them parallel to the side boards with the top edges flush. Cut the ends of the edging diagonally with a jigsaw to create an attractive mitered border. Secure the mitered ends together with wood glue after nailing each edging board in place with three nails.
Sand down any rough edges on the boards to minimize splinters, especially if children will be playing or working near the planter. Stain or paint each planter box in colors that complement your home and landscaping style. Layer 1 to 2 inches of gravel in the base of your planter before filling it with potting soil and inserting your plants. Repeat this entire process for each cedar planter box you desire.