One of the primary considerations gardeners must plan for when growing tomatoes upside down is where to hang them. According to the instructions for Topsy Turvy, a popular upside down tomato container manufacturer, tomato plants will pull out of a plywood base and should be anchored to a joist or rafter. If you don't want to attach upside down tomatoes to the rafters of your home, grow them from a trellis in your yard. A trellis similar in construction to grapevine arbor will support the weight of an upside down tomato plant.
Separate three landscaping timbers--two side timbers and one crosspiece timber. Drill a ½-inch hole through the end of the crosspiece timber, and the top end of each side timber.
Dig a post hole for each side timber that is spaced exactly as far apart as the distance between the two holes in the crosspiece timber. Make the post hole 1/3 the length of the side timbers.
Place the side timbers in the post holes with the end that has the drilled hole pointing upward. Align the timbers so that the drilled holes are pointed the same direction.
Fill in the post holes so that the landscaping timbers are held perpendicular to the ground.
Lift the crosspiece timber up so that the drilled holes in either end of the timber align with the drilled holes in the side pieces. Place a washer on one end of the carriage bolts and slip them through the holes on either end of the crosspiece and side pieces.
Slip the washer and nut on the other end of the carriage bolts and tighten them in place with a wrench.
Attach a set of screw hooks to the underside of the crosspiece. Each screw hook should be capable of holding 85 lbs. of weight. Space each screw hook approximately 36 inches apart to promote good circulation between plants.
Hang each plant from the hooks.