White light contains various colors, including red, orange, yellow, green, blue, indigo and violet. When plants harvest light for photosynthesis, they only absorb a few colors and reflect the rest.
Plants have several types of pigments, which absorb different light colors. The main pigment in plants is known as chlorophyll. Other accessory pigments include carotenoids.
Chlorophyll mainly absorbs violet, blue and red light, reflecting lighter blue, green and yellow light. Carotenoids absorb much of the light blue and green light, reflecting lighter green, yellow, orange and red light.
For green plants that mainly use chlorophyll to absorb light, blue light helps leaves to grow, while red light together with blue light helps flowers to bloom. Fluorescent light produces plenty of blue light, making it good for starting seedlings and promoting leafy growth.