Red Light & Sunflower Growth

Visible Light Waves

• The portion of light we see is just part of the electromagnetic spectrum. The unseen portions include gamma rays, x-rays and ultraviolet light. These different light waves cannot be seen without special equipment and are shorter than visible waves. The longer light waves are infrared, microwave and radio waves. Shorter waves have stronger energy than longer waves. Visible light is in the middle and has moderate strength.

Sunlight

• Sunlight is comprised of ultraviolet and infrared light waves as well as those in between. Chlorophyll is uniquely formed to use sunlight. It absorbs the red and blue light and reflects green light. The light wavelengths correspond to different energy levels. Blue is at the high end of the energy levels and is responsible for vegetative growth. Red light is lower in energy and produces a lower energy spike. The blue light drives flower and fruit production such as the huge flowers and seeds produced by a sunflower.

Sunflowers and Red Light

• Sunflowers are tall plants with huge flower heads. The influence of red light is easy to see in the large bloom but blue light is formative for the tall vegetation. Blue and red combined create both types of growth and enhance overall sunflower health. Part of the reason for this is carbon dioxide. Carbon dioxide is necessary for photosynthesis to take place. Blue light uses the most carbon dioxide while red lights use a medium amount. This gives red light only moderate energy.

Artificial Light and Sunflowers

• Fluorescent light carries more blue light which drives vegetative growth. This makes it ideal for starting sunflower seeds. Broad spectrum fluorescent lights are useful for flowering plants because they contain more red light. Plant lights have both red and blue but have not been found to be as beneficial to plants as fluorescent lighting. Orange-red lights absorb the easiest but do not drive photosynthesis as much as blue-green lights because of their lower energy contribution.