An installation (10) such as a box or cabinet for horticultural applications including a lighting space between a lighted plane (S) and a lighting plane (12) parallel to the lighted plane (S), with side walls (141, 142) that are at least partly light-reflective. The illuminated plane can be defined by the upper surface of a plant culture medium (P). A set (18) of light radiation sources, e.g. LEDs, arranged centrally relative to the lighting plane (12) projects light radiation towards the lighted plane (S) in the direction of a radiation emission axis (X102). The set of light radiation sources (100, 102) emits light radiation with a distribution of illuminance projected towards the lighted plane (S), which is nonuniform and gradually decreases as a function of the angle (θ) relative to the aforesaid radiation emission axis (X102), wherein the reflection of the radiation on the side walls (141, 142) facilitates uniform illuminance at the lighted plane (S).
