The plant culture tray (1) has a seating piece (2) for fixing the tray on a support. This piece comprises a fixing plate (2A) having a hole (14) for the passage of a fixing screw to the support. It has a part (7) for immobilising and positioning the tray on the seat. The tray has in its bottom part a tubular chimney (5) open at its base which extends orthogonally to the bottom towards the tray opening (6). This constitutes a housing for the seating positioning piece. Joining of the tray to the seating is obtained simply by fitting the housing on the seating immobilising piece. The chimney has an opening in its peripheral surface emerging in tray bottom face and in the tray side face (10). The size of the hole in the side face prevents the passage of the immobilising part.
