Lighting device for plants, cultivation greenhouse, plant factory and plant cultivation method

The invention provides a lighting device for plants, a cultivation greenhouse, a plant factory and a plant cultivation method. By employing the lighting device for plants, the psychological burden of workers can be relieved, and the lighting device irradiates light for facilitating the growth to plants efficiently. The synthesized light of emergent light of a lighting part for the growth and emergent light of an auxiliary lighting part has a first peak of photon flux when the wave length is larger than 400nm and smaller than 500nm, and has a second peak of photon flux when the wave length is larger than 600nm and smaller than 700nm, and the photon flux is smaller than the photon flux on the first peak and the photon flux on the second peak when the wave length is larger than 500nm and smaller than 600nm in the synthesized light.