This invention concerns an assembly of a first and a second container (1,10) for manufacturing a plant composition, whereby the first container (1) comprises a first inner space (8) for receiving growth medium for plants, which first inner space (8) is enclosed by a first wall (2) with a first upper edge (5) for defining a first upper side (3) and a first lower edge (6) for defining a first bottom (4), which second container (10) comprises a second inner space for receiving growth medium for plants, which second inner space is enclosed by a second wall (12) with a second upper edge (15) for defining a second upper side (13) and a second lower edge (16) for defining a second bottom (14), whereby the second bottom (14) has a smaller surface area than the first upper side (3), and the second container (10) is provided to be placed with respect to the first container (1) in such a way, that the second upper side (13) of the second container (10) is located above the first upper side (3) of the first container (1), and the second bottom (14) of the second container (10) is enclosed by the first wall (2) of the first container (1), and a portion of the first upper side (3) which is located between the first (2) and the second wall (12), is open along the first upper edge (5).
