A wood planter box is a great idea for the beginning gardener for a variety of reasons. You can keep your garden above ground, making it easier to control the soil composition. A planter box will also make it easier on your back, which is something any gardener can appreciate.
Even if you have limited carpentry knowledge, you can still build a wood planter box using the following steps.
Step 1 - Prepare the Area
Although your wood planter box will contain soil, you still need to prep the sub-surface to properly install the planter. Use a flat-edged shovel and garden rake to make the area reasonably flat and free of weeds and roots. Use any topsoil that you remove to backfill against the planter box when you’re done.
Step 2 - Build the Planter Box
Don't use pressure-treated wood as the harmful chemicals used in the treatment process could contaminate your garden. Regular lumber will do just fine for this application and will last at least a few years before rotting.
Using your tape measure, mark off each 2x12 inch board with the desired width and length of the box (in this case, 10 feet long and 6 feet wide). Carefully make the required cuts with your circular saw.
Next, assemble the box using nails or screws to secure each piece. Use at least 3-inch fasteners and install at least four on each side of each corner. It’s a good idea to lay the wood planter box out and assemble it in the area you want to keep it in to avoid moving it twice. Before securing the last piece, use your framing square to check each corner.
Step 3 - Install the Planter Box
Cut the 2x4 into 12 inch pieces. Next, cut the end of each piece into a point with your circular saw. Cut each 12 inch piece in half, leaving you with two 6 inch spikes. You’ll need a total of six to place around the perimeter of the planter box.
Place two stakes evenly apart on each side of the planter box and drive them into the ground. Secure them to the box with either nails or screws. This will help hold the box together against the pressure of the dirt inside.
Step 4 - Backfill the Planter Box
Use leftover topsoil to backfill around the box and inside. Use the excess soil left over from the leveling process. Place about 2 to 3 inches of fill around the entire perimeter of the planter box and use your foot to compact the soil. This will also help in preventing the box from spreading apart over time.
Use premium-grade topsoil to fill the planter box.