A floatable plant growth system is provided. The system comprises an upper tray (10) and a lower tray (20). The upper tray has a plurality of downwardly tapering cells (11) for receiving plant growth material, with each of the plant cells having an opening (13) at its bottom. The lower tray has a plurality of upwardly tapering cells (21) that trap air, enabling the system to float in use. The upper tray is removably mateable with the lower tray such that the plant cells of the upper tray are located in the space (27) between the air cells of the lower tray. The lower tray is provided with a plurality of openings (26). When the upper and lower trays are mated together and placed in a body of liquid, liquid enters the mated tray configuration (10, 20) through the openings (26) of the lower tray, fills the space (27) that is below the plant cells (11) between the air cells (21) of the lower tray, and in use may be taken up through the bottom opening (13) of each upper tray plant cell.