Plants need light to grow, but does the colour of light matter as well? According to photographer and inventor John Ott, light colour greatly affects plant growth. His experiments indicated that colour impacts blossoming, fruit-bearing and even gender.
Light quality refers to the colour or wavelength the light emits. Red-orange hues have long wavelengths, yellow-green are medium, and blue-violet are short wavelengths.
The pigments within a plant absorb light and use the energy for photosynthesis. Plants absorb different colours at different levels. Blue-violet light offers the highest absorption level, followed by red-orange. Plants are green in colour because they reflect green light rather than absorb it.
Blue-violet light promotes leaf growth, while red-orange combined with blue fosters flowering.
Types of Light
Natural sunlight emits full-spectrum colour, making it ideal for plant growth. Some artificial lights filter out certain colours and are ineffective for plant growth. Incandescent and fluorescent light produce varying colour wavelengths and are good for growing indoor plants.
Evaluating Light Quality
A spectrometer can evaluate the quality of an artificial light source by showing you what wavelengths are in the light. You can purchase one or make one at home using a cardboard tube, black card stock and an old CD.