A plant tray 10 assembly for holding plants and associated media comprising: a base retaining tray 14 having an upper surface 13 defining a plurality of cavities 18 therein for receiving plant pots therein, the plant pots containing the plants and associated media; and a top plate 12 mounted on said base retaining tray 14 and being displaceable relative thereto in a plane substantially parallel to said upper surface, the top plate 12 having a plurality of apertures 16 defined therein and which extend transversely therethrough in a direction substantially normal to said plane, the apertures 16 of the top plate corresponding to the cavities 18 in the base retaining tray 14 in number and configuration, the top plate and the base retaining tray 14 being relatively displaceable between a loading/unloading position and an locked operative position of the plant tray assembly, 10 wherein the apertures 16 of the top plate 12 and the cavities 18 of the base retaining tray 14 are substantially aligned in said loading/unloading position such as to define transversely open plant receiving channels 20 the plant receiving channels 20 permitting the plant pots to be passed therethrough and received within the cavities 16 of the base retaining tray 14 such that the plants protrude through the apertures of the top plate, and wherein said apertures 16 of the top plate 12 and the cavities 18 of the base retaining tray 14 are at least partially misaligned in said locked operative position such that the plant pots are trapped within the plant tray assembly 10 while the plants remain protruding through the apertures 16 of the top plate. 12 a base retaining tray 14 having an upper surface 13 defining a plurality of cavities 18 therein for receiving plant pots therein, the plant pots containing the plants and associated media; and a top plate 12 mounted on said base retaining tray 14 and being displaceable relative thereto in a plane substantially parallel to said upper surface, the top plate 12 having a plurality of apertures 16 defined therein and which extend transversely therethrough in a direction substantially normal to said plane, the apertures 16 of the top plate corresponding to the cavities 18 in the base retaining tray 14 in number and configuration, the top plate and the base retaining tray 14 being relatively displaceable between a loading/unloading position and an locked operative position of the plant tray assembly, 10 wherein the apertures 16 of the top plate 12 and the cavities 18 of the base retaining tray 14 are substantially aligned in said loading/unloading position such as to define transversely open plant receiving channels 20 the plant receiving channels 20 permitting the plant pots to be passed therethrough and received within the cavities 16 of the base retaining tray 14 such that the plants protrude through the apertures of the top plate, and wherein said apertures 16 of the top plate 12 and the cavities 18 of the base retaining tray 14 are at least partially misaligned in said locked operative position such that the plant pots are trapped within the plant tray assembly 10 while the plants remain protruding through the apertures 16 of the top plate. 12