Garden planters add flexibility and design to your gardening space. You can build your own large garden planter from landscaping materials that are already designed for outdoor use. Design the size and shape of the large planter to fit your available space. Make a large, rectangular planter to border your patio or make a large, square planter to create a space for a kitchen garden. The building principles are the same, no matter how large, or small, your landscape timber planter needs to be.
Stack two 8-foot-long landscape timbers so that the ends are flush. Measure and mark the top timber in 1-foot increments for the length of the timber. Hammer an 8-inch-long timber nail through each mark on the top landscape timber and straight into the bottom landscape timber.
Stack another landscape timber on top of the first two with the ends flush. Measure and mark the top timber in 8-inch increments across the top timber. Hammer an 8-inch long timber nail through each mark on the top landscape timber and straight into the second landscape timber.
Stack a fourth landscape timber on top of the first three. Measure and mark the top timber 2 inches from each end and 33 inches from each end. Hammer 8-inch timber nails through each mark.
Repeat steps one through three to make another side of the large, rectangular planter.
Cut four 8-foot -ong landscape timbers in half.
Stack two timbers with the ends flush. Mark the top timber 14 inches from each end. Secure the timbers together with 8-inch timber nails. Stack another 4-foot timber on top of the first two. Mark the top timber 8 inches from each end. Secure the top timber to the first two with 8-inch timber nails.
Stack a fourth timber on top of the first three. Mark the center of the top timber and 4 inches from each end. Secure the top timber to the stack with 8-inch timber nails over the marks.
Repeat steps six and seven to make the fourth side of the large garden planter. Attach the four sides of the rectangular planter with two L brackets in each inside corner. Place one bracket in the center of the top timbers and one in the center of the bottom timbers
Measure the length and width of the base of the large planter from the outside edges. Cut a sheet of 1/2-inch-thick treated plywood equal to the dimensions. Attach the plywood sheet to the underside of the planter with decking screws around the perimeter. Place the screws every 2 to 3 inches. Drill 1/2-inch diameter drainage holes every 3 to 4 inches over the plywood sheet.
Cut plastic sheeting to fit inside the planter. Attach the plastic to the timbers with a staple gun. Puncture the plastic over the drainage holes.