You'll need a couple of 18-gallon or larger rubber tote boxes with lids, preferably in a dark color. The boxes need to be wider than they are deep. Try to get one with straight sides. You'll also need a 5-inch pond basket that you can obtain from a landscape supply store. Finally, you'll need 2 feet of 1.5-inch plastic or PVC pipe. For tools you'll need a drill with a quarter inch and one and a half inch bit and a jig saw.
Cut the top half off one tub so there are about 6 inches of side left. Flip the tub half over and cut a hole in the center with the jig saw. The hole should be large enough so that the pond basket fits snugly inside the hole. Next drill quarter-inch holes in the bottom of the tub half so the holes are scattered evenly all over the bottom, 2 to 3 inches apart. Cut a 1.5- inch hole at one corner for the watering pipe. Drill quarter-inch holes around the bottom 4 inches of the watering pipe. Push the drilled end of the watering pipe through the hole in the upside down tub half.
Set the uncut tub right-side-up and place the upside-down tub half inside. Set the pond basket in the center hole in the bottom of the half tub. The basket will provide a contact point between soil and the water reservoir so that moisture wicks up into the root system without saturating the soil and causing root rot. Insert the PVC pipe into the corner hole you cut for it. This creates a watering pipe through which you can refill the water reservoir. Drill a quarter-inch drain hole about 5 inches from the bottom so that it passes through both tubs. This prevents the water level in the reservoir from getting too high. Use a box cutter to trim the center out of the tub lid. Finally, fill the box with whatever soil mixture you prefer for the plants you will be planting in the box
Cut a sheet of black tarp or plastic the size of the lid. You'll have to cut a hole in the plastic to fit over the watering pipe. Stretch it over the top of the grow box and then snap the lid that you cut the top out of down over the plastic to hold it in place. The plastic sheet will keep the earth warm by absorbing heat and will help to hold the moisture in the soil. Cut an "X" in the plastic where you want to plant your seedlings and plant them in the soil. Fill the water reservoir until water comes out of the drain hole. Mix any fertilizer mixture you plan to use with the water in the reservoir. You should only have to refill the water reservoir every four days or so. Check the soil every day at first to prevent it from becoming too dry.