Abstract: A trough which spirals in several turns in a plane about a vertical central axis has an arrangement of rails superimposed on it so the rails radiate from the vertical central axis and divide the trough into cells. Potted plants are placed in the cells, initially near the center, with spacing between them along the spiral. As the plants grow, either the trough or the arrangement of rails, or both, is turned about the central axis, so that the rails, engaging the pots, propel the potted plants outwards along the spiral, thus giving the plants more room. The plants can be watered by introducing water into the trough.