Outdoor planters add style and dimension to your landscape. You should build an outdoor wood planter from wood that will withstand the elements and that will naturally repel insects. Cedar wood is a good choice for your outdoor planter, as it will weather well over time, and the wood contains oil that most insects do not enjoy. Look for cedar boards and the other materials necessary to build an outdoor planter from your local home improvement store.
Determine the desired size of your outdoor planter. You can make any size planter you like, but if you are placing the planter beneath a window or on the patio, space may be an issue. Consider, too, the types of plants you plan to cultivate.
Measure and mark the cedar plywood to fit the dimensions of the four sides and the bottom of your planter. For example, if you're making a rectangular planter that's 16 inches high, 18 inches long and 12 inches deep, you'll need two sides measuring 16 inches wide by 18 inches long to make the length of your rectangle. Cut the plywood for the sides of the rectangle 13 inches wide by 17 inches long to create the depth of your planter. The sides measure 1 inch larger on the width and the length to account for the thickness of the cedar plywood. The bottom board of your rectangular planter will measure 18 inches long by 11 inches wide as it will fit inside the four sides.
Cut the plywood on your marks.
Attach the two 16-inch by 18-inch plywood sheets to the bottom panel with decking screws. Place the bottom panel on a flat work surface and butt the front and back panels flush against the 18-inch-long sides of the bottom board. Insert the screws through the side panels into the edge of the bottom panel. Place screws every 2 inches.
Butt the remaining side panels flush against the attached side and bottom panels to enclose your box. Attach the panels together with decking screws along the side and bottom edges.
Drill holes for drainage into the bottom section of the wood planter. Cut a sheet of plastic liner to fit inside the planter. Attach it with a staple gun. Puncture the plastic wherever it falls over the drainage holes.