What Color Light Causes Plants to Grow Best?

Many people use fluorescent lights for their plants.

Light produces a wide spectrum of colors. Plants require light for photosynthesis and benefit most from the red and blue spectrums of light. Sunlight produces both of these, as do other kinds of light bulbs.

Color Temperature in Light

Color temperature is measured with the Kelvin scale. The higher the degree of Kelvin, the light appears more blue; the lower the degree of Kelvin, the light appears more red. Color temperature is not rated for how hot or cold the actual temperature is but the way we perceive the the light.

Red and Blue Spectrum

Plants primarily use the red and blue spectrum of light for photosynthesis and creating flowers. Fluorescent bulbs give light more on the blue end of the spectrum. Incandescent lights give light more on the red/yellow end of the spectrum. The combination of red and blue spectrum lighting is what causes grow lights to appear purple.

Sunlight

Plants thrive best in natural sunlight. Sunlight provides the full range of the color spectrum and gives the plant the best light source. Many light bulbs now claim to emulate daylight.

References

• University of Minnesota Extension; Light Requirements for Houseplants; David Whiting
• University of Minnesota Extension; Yard and Gardening News: "Fellow Gardeners, Start Your Seeds"; Meleah Maynard; Feb 2009
• University of Minnesota Extension: Yard and Gardening News; "How to Kill a Houseplant in Five Easy Steps"; Carl Hoffman; January 2008
• Ultra LED Lights: Full Spectrum Grow Light