More in Outdoors
You can build boxes of four different sizes to create a useful space for gardening. The large and small boxes are open squares or rectangles (the size is up to you) made of composite; the ends are simply butted, so no mitering is necessary. For the open planters, simply overlap a long board and a short board and join the ends with four screws. Do this twice to make two L-shaped pieces and then join them to form a rectangle.
The medium box so that it can be fitted with a bottom after the boxes have been stacked (Image 1). It is built like the others except that it has an inner frame of 2x4s at the inside bottom that will support a floor. The floor is simply a series of 2x10 boards placed horizontally across the frame with a gap between them for drainage is constructed (Image 2).
You can also make one extra-large planter box to serve as an enclosure for some large planted citrus trees. It also is built out of a composite material because it will be in constant contact with soil and moisture. This box consists of two 2x8s 10' long and two 2x8s 4' long. These four boards are joined into a rectangular shape in the same way as the smaller planter boxes and then set in place.
An important thing to remember when building a box out of composite material is to leave space between the slats at the bottom. It provides drainage for the plants as they grow.