The present invention relates to a method for forming a connecting slit (11,13) in a plant container, such as a pot or a tray for plants, to which connecting slit (11,13) a label (30) comprising an information part can be detachably connected, wherein the connecting slit (11,13) is mechanically formed in the plant container by means of a cutting element. The present invention further relates to plant container, such as a pot or a tray for plants, produced by using a method as described above. The present invention finally relates to a combination of such a plant container and a label.