Even though red light is the most effective for photosynthesis, red light alone would cause poor growth in plants, such as overly elongated stems, so blue light is added to keep plants compact and in a more typical shape.
On the other hand, plants cannot be grown only in blue light because this would have a negative impact on their growth and development. Over the years, researchers have discovered that a mix of high red light and a low percentage of blue light is best for the yield of plants that already receive light from the sun.
