Wooden containers, as landscape elements, not only sustain small parcels of greenery on a deck or on a patio, but they are visually appealing in their own right. The modular design of the freestanding planter with optional benches that is shown below allows you to use your imagination to fill a space of just about any size or shape.
Because the chemicals in pressure-treated wood can harm many plants, buy ordinary lumber for planters and flower boxes. Countersink the heads of all finishing nails and plug the holes with waterproof wood putty, then paint or stain the wood to seal it. Before filling a container with soil for planting, cover the bottom with galvanized screening and 1 to 2 inches of gravel.
A modular system
Boxes for planting can be freestanding units or components of a larger assemblage having one or more benches. A box consists of five courses of 2-by-4s with a 2-by-2 brace in each corner and a cap of mitered 2-by-4s. These dimensions yield a planter sufficiently large for an ornamental shrub or an interesting flower arrangement, yet not too heavy to be placed on a deck. Each bench uses seven 2-by-4s, up to 8 feet long. Because the presence of benches affects box construction, plan the unit before you begin building it.
Building the base
Cut four 2-foot lengths of 2-by-4 and set them on edge to form a square. For best results, orient the end grain of the pieces as shown in the photo at right. With a ⅛-inch bit, drill two pilot holes through the face of each 2-by-4 where it overlaps the adjacent piece, then fasten each corner with 2½-inch galvanized nails. For the feet, cut two 2-by-4s, 25¾ inches long. Drill two pilot holes at each end of the feet, then lay them across the frame, about 2 inches in from the edges. Square the frame and nail the feet in place. Cut five pieces of 2-by-4, 22¼ inches long. Turn the structure over and nail the 2-by-4s to the feet as shown above, leaving uniform drainage spaces between the boards.
For a planter that looks professionally built, it is essential that all the 2-by-4 pieces be exactly the same length. If you don’t have a table saw, you can achieve the results with a circular saw and the jig shown above. A 2-by-6 at least 6 feet long serves as the base. Near one end, screw a piece of 2-by-2 to act as an end stop. A little more than 2 feet from the end stop, screw an 18-inch 2-by-2 to the base, flush against the edge, as a side stop. Mark a 2-by-4 with a cut line 2 feet from one end, and set the board against the side and end stops. Place the blade of your saw at the cut line, then set a piece of ¾-inch plywood alongside the saw’s baseplate. Put the saw aside and screw the plywood to the side stop as a saw guide. To use the jig, set your saw for a 2-inch depth. Slide a 2-by-4 against the stops, place the saw baseplate against the guide, and cut through.
Putting the box together
For the corner braces, cut four 16-inch lengths of 2-by-2. Hold a brace firmly in one corner of the base and drill ⅛-inch pilot holes through the 2-by-2 and into the 2-by-4s at the corner, offsetting the holes so they do not meet. Attach the brace with 2½-inch galvanized screws. Repeat at the other corners. Assemble the second course as you did the frame for the base, and slip it over the braces, forming the corner-joint pattern shown at left. Drill pilot holes and screw the corner braces to this course.
Finishing the box
For boxes without benches, repeat the preceding step to add the remaining three courses. However, if your plan includes benches, stop after the third course and build the fourth course as shown here—three-sided to support one bench end or two-sided to support the ends of two benches. Nail a two- or three-sided course together, as called for. Lay it on the third course, and screw the corner braces to it. Set the fifth course in place, supporting it with a scrap piece of 2-by-4 in the case of a two-sided fourth course (inset). Screw the corner braces to the fifth course. For the cap, cut four lengths of 2-by-4, 26½ inches long, then miter the ends with a backsaw and a miter box. Nail the cap pieces to the fifth course with finishing nails, set the heads, and hide the holes with waterproof wood putty.
Fitting bench slats
Place the boxes in their final locations with open sides of the fourth course facing each other. Measure the distance between the interior faces of the boxes, and cut seven 2-by-4 slats to that length. Insert the slats on edge into the space in the fourth course so that the ends are flush with the interior faces of the boxes (above). Place ⅜-inch spacers—plywood works well—between the slats at both ends of the bench (inset), then center the bench in the fourth course.
Completing the fourth course
Measure the gap between the bench and the inside edge of the fourth course (left), and cut a 2-by-4 filler to match. Fit the filler into the gap, then nail through the fourth course into the end of the filler to secure it. (You need not anchor the filler to the bench.) On the other side of the bench, slide a piece of 2-by-4 into the gap and against the bench. Mark a trim line on the board using the outside of the box as a guide, then cut the filler and nail it in place.