The invention relates to modular greenhouses for growing fruits and vegetables comprising a frame formed from piles (1), posts (2), longitudinal beams (3), transverse beams (4), and a cambered roof (5) formed from arched beams or a flat roof (5) formed from springs; the greenhouses being equipped with a system for fully opening/closing the roof, comprising an electric motor (6) with a reduction drive (7), and a transmission (8), which are connected to a rotary shaft (12), being rigidly mounted in the center of the roof, and connected to a helical shaft, spanning the entire width of the frame, and to a movable reduction drive connected to the rotary shaft.