I make planter boxes from recycled wood. Here is an example of a completed planter box. This particular box is 2 cubic feet.

Here is a top view looking down inside the planter box. I have not finished the trim piece in this particular photo. Notice the bottom is comprised of 2x4 wood placed at forty-five degree angles. I placed the wood at an angle for structural strength and rigidity in the box frame.

The photo below shows the planter box upside down. Note the box has openings at bottom near 4x4 corner legs to allow water to drain. On some planter boxes I also drill additional 1-inch holes when I want additional drainage capability.

I created a Blueprint of the dimensions. These do not have to be exact. The 2x4 horizontal sides are drilled with pocket holes to attach to the 4x4 corner posts.

Having already built three two-cubic foot planter boxes, it was time to build a fourth box. The dimensions of this box are approximately 3.42 feet (length) by 3.42 feet (width) by 4 feet (height). It will be home to an apple tree. In this first photo, I cut four 4x4s into 4 foot lengths. I cut eight 2x4s to 34 inch length. Note: when the 2x4s are joined to the 4x4s, the width and length of the planter box will be increased by 7 inches. I also drilled pocket holes to join the 2x4s to the 4x4 posts. This preparation is necessary before I can begin to assemble the box.

The next step is to build one side of the planter box. This will require two 2x4s and two 4x4s. I use pipe clamps to hold everything together before I put deck screws into the pocket holes. I pre-drill small holes into the 4x4s through the pocket holes. This starter hole keeps the wood from splitting when driving deck screws in. Note: I stack two panel boards underneath each end of the 2x4s before attaching the 2x4s to the 4x4s. Using a stack of two panels will displace the 2x4s enough to give me a recessed panel look when I ultimately put a single panel on outside of the planter box.

The process for creating the second side is identical to the first (above). The next step is attaching the two halves together. I use pipe clamps and temporary angled bracing for structural rigidity. The pair of adjacent 2x4s stacked vertically serve as spacers. They are not being attached. They help me determine how high the bottom horizontal 2x4 brace needs to be mounted.

Now the fourth side of the box is attached. Notice how the 2x4s that are already attached are not centered on the 4x4s but rather offset? This is purposefully done to allow for a recessed look when I later attach the exterior panel siding.

With all four sides attached the next step is to add a floor. I purposefully attach the floor at forty-five degree angles for structural strength. This prevents the planter box from racking or twisting.

Here is a view of the floor of the completed planter box.

The large planter box is now finished. I used recycled wood for the bottom and structure. I used new fence siding for the panelling because I ran-out of recycled wood! This box is 64 cubic feet in volume. I will be planting an apple tree in the box.