The tip of the leaf of a plant senses blue light and signals the plant to grow in the direction of the blue light.
The red glow of a sunset is what signals the plant when it is time to bloom. A plant kept in a dark closet can be signaled to flower with just a short flash of red light.
Plants use both blue and red light to feed themselves but slightly favor red.
Plants appear mostly green because they are reflecting most of the green light that hits them, it doesn’t get used by the plant.
If your plant is not growing well, try adding more blue light. If you’re not getting flowers try more red light.