Light Spectrum & Plant Growth

The full color spectrum can be seen through a prism.

Light is essential for growth and food production in all plants. Plants grow naturally under a full light spectrum, though light of different wavelengths---that is, different colors---can encourage better, faster growth.

Color Spectrum

White light is comprised of all colors, as seen when it is broken up through a prism. An object's color is determined by the wavelength the object reflects---plants, for example, reflect green light and, therefore, appear green.

Chlorophyll

Chlorophyll, the green-tinted pigment in plants, is a pivotal component of the process of photosynthesis, which absorbs light to produce starch. Chlorophyll absorbs the entire color spectrum except for light of the green wavelength. Of the two kinds of chlorophyll, A and B, chlorophyll A tends to absorb red and violet light, while chlorophyll B tends to absorb blue and orange light.

Grow Lights

Gardeners can perform indoor experiments on their plants with grow lights and light-emitting diodes (LEDs), which can eliminate the green wavelength, promoting ideal growth. Other varieties of light can encourage different kinds of growth, such as high-pressure sodium bulbs, which produce light of the red wavelength and tend to promote flowering, and metal halide bulbs, which produce light of the blue wavelength and tend to encourage leaf production.

References

• The Succulent Plant Page: About Light and Lighting
• Estrella Mountain Community College, Online Biology Book: Photosynthesis
• AFC Greenhouses: Indoor Plant Grow Light Guide