Growing upside down tomatoes is an alternative way to plant when you have limited gardening space. You can plant a single upside down tomato plant in a five-gallon bucket or you can build your own upside down tomato garden out of wood to grow several plants at once. The tomatoes grow just as well upside down as they do right side up, but there is no need to stake the plants as they grow and become heavy.
Determine how many tomato plants you plan to grow in your upside down tomato garden. The overall depth of the garden box should be 15 inches to give the tomato plant's roots adequate depth. You should also allow a 1-foot-by-2-foot area of space for each plant. For example, if you wish to plant four tomato plants, build the wood garden box 4 feet long by 2 feet wide by 15 inches deep.
Cut two sections of 1/2-inch thick cedar plywood, equal to the desired length of the upside down tomato garden, by 15 inches wide. These are the front and back sides of the tomato garden box. Cut two sections of 1/2-inch thick cedar plywood 1 inch less than the desired width of the tomato garden, by 15 inches long. These are the two sides of the garden box.
Cut one section of 1/2-inch thick cedar plywood equal to the desired length of the garden, plus 1 inch, by the desired width of the garden, plus 1 inch. This is the bottom of the tomato garden. The variation in measurements allows for the width of the cedar boards.
Draw lines to section the bottom of the garden off in 1-foot increments along the length. Find the center points of each 1-foot block and drill a 2-inch hole for the tomato plants.
Attach the front cedar board to one of the side boards with decking screws along the seam. The side panel should butt against the back edge of the front panel. The top and bottom edges should be flush. Attach the remaining side panel to the opposite end of the front panel.
Attach the back panel to the back edges of the side panels. You should have four sides of the garden box connected. Attach the bottom of the wood box with decking screws around the perimeter. Place the screws every 3 inches or so.
Insert one 2-inch decking screw to the center of each side panel. Hook a length of chain onto an S hook. Hook the S hook to the decking screw. Hang the wood garden box at least 5 feet from the ground. You can use a strong garden arbor or two shepherd's hooks to hang the upside down tomato garden.
Insert the roots of the tomato plants through the holes along the bottom of the garden. Fill in the box with potting soil to hold the plants firmly in place.