The invention relates to an assembly system for forming planters applicable for forming planters formed by means of connecting modular elements, comprising engagement parts (5) which are fixed on the elements (1) forming the side walls of the planters, and insertion parts (6) in the mentioned engagement parts (5) for establishing, by means of coupling said parts (5 and 6), the connections among the elements (1) of the side walls of the planters and the connections of said elements (1) of the side walls with a base element (2) and with a mouth element (3) in the planters.
