Method and system for lighting plants grown in a greenhouse using interlight lamps placed between two adjacent rows of plants, wherein the axis (a) of the cone (K) of light emission of said interlight lamps (5, 6, 7) is provided with an inclination angle with respect to the ground (S) and/or to a plane parallel to the ground and/or to a horizontal direction, which angle is variable according to the height of placement from the ground of said lamp with respect to the plant height, i.e. to the point of emergence of plant trunk with respect to the ground.
