This invention concerns apparatus for growing plants comprising a column (100) of pots (102) stacked one above the other to define an enclosure for housing plants. Each pot (102) defines a chamber (104) for holding a plant. Separators for separating pots of the column are provided and the separators define an enclosed headspace around a top of at least two of the pots where plants project from the chamber. The chamber comprises a passageway (106) that provides a continuous flow path for air through the column (100) without requiring the air to flow through the chamber (104). This flow path includes the headspaces above the at least two of the pots (102).