Abstract: The invention as described in the present specification provides an improved container for growing seedlings for transplanting. The container is split in half longitudinally. The two half sections may be separate, in which case they are held together by the walls of a crate into which a number of the containers are placed. Alternatively, the sections may be connected together along their bottom margins by a hinge. In this latter case the container can be opened in the manner of a book to expose the seedling and root ball for easy extraction. Each half section comprises a pair of spaced, inwardly-protruding shoulders and a web connecting the shoulders. When the two half sections are pressed together, the shoulders mate -- the opposed webs and shoulders then define an open-topped cell having an air-pruning opening at the base thereof. The webs are formed to provide vertical grooves running the length of the cell to the air-pruning opening.