Abstract: The present invention comprises a tray which includes: a flat frame having a plurality of compartments, each having an opened bottom but in which may be seated a plant-growing cartridge; and retractable supports movable between a stored position, wherein they lie in the longitudinal plane of the frame, and an upstanding position, wherein they lie in a plane describing an angle of more than 90.degree. with that of the stored position, thereby leaving a space beneath the frame to allow air circulation beneath the cartridges and to plants therein.