A structure for cultivating plants out of ground, particularly for producing cut flowers, comprises at least a cultivation platform (10) having at least a cavity (12a, 12b, 12c) in the form of a container intended to receive a plant with the respective earth, and support means (34) which can be associated with said platform (10) in order to keep it raised with respect to the ground. The support means (34) are adapted to support a plurality of cultivation platforms (10) arranged according to a condition aligned and side by side so as to make a modular structure, each cultivation platform (10) being made by molding a plastic material, with walls adapted to provide a thermal insulation of the plants received in said containers (12a, 12b, 12c), with respect to the outer environment.