How Do Different Light Spectrums Affect Plant Growth?
- Light rays are composed of various wavelengths, which determine their color. Light spectrums can be red, orange, yellow, blue, green, violet or indigo. Because plant leaves are usually green, they tend to deflect yellow and green areas of the color spectrum. Red and blue spectrums are the most important for plant growth. According to the Colorado State University Extension, blue light encourages leaf growth, and red light helps with the flowering stages. Green light waves are the least effective.
- Natural light is the optimal source for most plants since it provides the whole spectrum of wavelengths, as well as a balance of red and blue light. Situate indoor plants near windows if possible, to provide maximum natural light. If you need to supplement natural light with an artificial light source, avoid incandescent lights and opt for fluorescent bulbs. According to the Colorado State University Extension, incandescent bulbs not only emit excessive amounts of heat, but they also lack the most beneficial wavelengths to support plant growth.
- In addition to light quality, which refers to the type of light wavelengths provided for plants, light intensity is another important factor in healthy plant growth and development. Light intensity refers to the amount of light received, and is measured in units known as foot-candles. To evaluate indoor light levels, you can purchase a light meter at your local home and garden center. For best planting results, you must provide good light quality as well as appropriate light intensity.
- The Colorado State University Extension provides a few additional recommendations for plant-light quality. For seed germination, blue wavelengths are especially beneficial, and can be obtained from fluorescent cool white lamps. Broad-spectrum fluorescent bulbs are more appropriate for flowering plants. According to the University of Illinois Extension, grow lights are not necessary for indoor gardens. Situate indoor plants that need full sun in a south-facing window, since this will provide the most natural light.