Determine the area where you want the planter box to be. Measure the area (8 feet by 4 feet) with the tape measure. Use the spray paint to outline the area.
Shovel out the grass and weeds inside the painted area to clear the soil of all debris.
Dig a 6-inch-deep trench along the painted lines and as wide as one landscape timber.
Place a landscape timber in each trench with the 4-foot sections resting inside the 8-foot sections. Lay another landscape timber on top of this first layer, nail in place with the nails on each end of the timbers, and equally spaced along the timber.
Add two more layers to the timbers and nail these in place as well.
Measure and cut the correct size of landscape fabric to place inside the box on top of the soil. Cut a hole in the fabric in the desired location for plants.