Pumpkins can be grown in large containers, 5 gallons or larger. Place the container in a sunny spot. The plants will sprawl, so give the container room, or grow the pumpkin vines on a trellis. As the pumpkins develop on the trellis, you may need to rig cloth slings to support the weight of the fruit. For the best result, allow the plant to set only two or three pumpkins.