How Light Affects Plants

Light spectrum
Light is made of energy waves that appear as different colors, depending on how much energy they emit. Red, orange, yellow, blue, green, violet, and indigo-the colors of the rainbow-are colors of light we can see with the unaided eye and  ultra-violet light we cannot see.

Blue light
Helping plants put out healthy leaf growth. Natural light and cool-white fluorescent lights tend to be high in the blue range.

Red light
Affects flowering and plant reproduction, when plants don't get enough red light, they may not bloom well or at all. Both natural light and most incandescent light bulbs tend to be high in the red range. Cool-white fluorescent lights tend to have little red light.

Brightness
The amount of light is important.  Some flowering houseplants may not bloom indoors because they don't get enough light. If shade plants get too much bright light, their leaves burn.

Phototropism
The way plants lean or bend toward light. Turn indoor plants frequently to keep straight.

 

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Both of these pictures are of Black Dragon Coleus. They were both planted 28 days ago in plastic domed "greenhouses". The one on the left was grown under lights in the GrowLab and the one on the right was grown beside an East facing window.