Various different wavelengths, or colors, of light have different effects on the growth of different species of plant. Plants, like animals, have a number of unique needs that vary from one species to the next. The light they respond best to is among these characteristics.
Experiments involving the effects of different light colors and sources have been ongoing for many years. Even the average elementary school science fair is likely to have at least one demonstration. NASA has also seen the benefit of investigating the long-term and short-term impact of different wavelengths of light on the growth and production rate of vegetables and other plants. What has been discovered is that all plants are very different, though most will respond best to blue or cool colors during their early growth period. Later, unique characteristics change those needs based on their native habitat and growing conditions. It has been discovered that some plants achieve a peak in their photosynthetic process during certain hours of the day. Plants that reach this peak during the early morning hours respond more favorably to cooler tones throughout their life cycle. Meanwhile, plants that reach their peak during the afternoon respond to warmer colors of light.