An earth box is a protected, self-watering system for growing plants. The system allows for growing vegetables and other large outdoor plants with minimal water usage and in a limited amount of space. Developed to help feed hungry people in smaller, undeveloped countries, earth boxes and similar systems provide the ability to grow your own food in small areas such as apartment balconies and small backyards in a low-maintenance process.
Turn one of the 5-gallon buckets upside down and, using the plastic drinking cup as a guide, cut a hole in the center of the bucket's bottom large enough to allow the cup to sit down into it without falling through. You can do this by tracing around the lip of the cup to mark where you want to place the hole, but remember that you will need to drill your starter hole and cut your hole about 1/16-inch inside that mark to prevent from making the hole too big. Drill your starter hole and cut out the circle using a jigsaw.
Outside of the center hole drill several small holes in the bottom of the bucket. Drill between 14 and 20 holes using a drill bit that is no smaller than 1/16 inch and no larger than 3/8 inch.
Drill or cut another hole in the bottom of the bucket near the edge that will accommodate the PVC pipe. The hole should be about the diameter of the outside edge of the PVC to allow the pipe to fit snugly in the hole.
Place the bucket with the holes inside of the other bucket. This will create a gap between the two buckets, which is where your water reservoir will be. Drill a hole in the outer bucket just beneath the location of the bottom of the inside bucket. This will form your water overflow hole and must be as high as possible but below the level of the inside bucket.
Cut the end of PVC pipe on an angle and place the pipe into the small hole in the bottom of the bucket and push it down until it rests on the bottom of the outer bucket. Cut the pipe so that it sticks up out of the buckets at least 4 inches. This will be the fill tube through which you will add water to the bucket when needed.
Place the plastic cup into its hole and be sure that it rests on the bottom of the outer bucket or very near the bottom. Pull the cup back out, make some slits into the sides or drill a few holes to allow the water to flow into the cup and place the cup back in the hole.
Place the lid on the top of the bucket and mark where the water fill tube hits the bucket. Cut out the hole to allow the tube to pass through. Cut a 3- or 4-inch hole in the center of the lid to allow the plant to grow through, or, if planning on planting more than one plant, cut one stem hole for each. Alternatively, cut a large hole in the center of the lid, basically cutting the outer rim off of the lid and use a sheet of plastic to cover the top of the bucket with the ring over top of it to hold it on. Cut X-shaped slits in the plastic where the plant will be planted.
Fill the bucket with sphagnum moss or other planting medium that will allow for wicking to occur. The cup in the center will hold some of the planting medium down into the water and the plant will draw up the water as it needs it.
Mix fertilizer into the medium, plant your plant and water well and place the lid on firmly. Fill the reservoir with water until it overflows out of the overflow hole.