How Does Red Light Affect Plants?

Certain colors of light can improve a plant's growth.

Plants are affected by the light they absorb--not just in quantity but also quality. Plants grow better when they are able to take in higher amounts of red and blue light.

Light Quality

Wavelengths determine the quality, or color, of light. In order to complete photosynthesis, a plant needs every wavelength, but it will grow best with higher amounts of red and blue light.

Red Light Benefits

Red light encourages plants to bud and flower.

When red light is absorbed by a plant, it promotes flowering and budding, according to the "Oregon State University Extension Service Master Gardener Handbook."

Red Light Disadvantages

When combined with too little light of other wavelengths, too much red light can be detrimental to a plant's growth, causing it to become spindly, warns experts from the Government of Alberta, Canada, Agriculture and Rural Development.

Best Use of Red Light

Red light should be used in conjunction with blue light, which encourages leafy growth and development. When combined, blue and red light can bring about the greatest degree of healthy growth and flowering.

Artifical Lighting

Gardeners can nuture plant growth with the right lighting.

Artificial lighting can be used to encourage plant growth. Fluorescent lights contain high levels of blue, making them especially beneficial for new seedlings and promoting general plant growth. Incandescent lights, which have high levels of red and orange light, can be added to increase flowering. Light bulbs, however, should not be placed too close to plants; the heat produced by incandescent lights can damage the plants.

References

• "Oregon State University Extension Service Master Gardener Handbook;" Light
• Government of Alberta, Canada, Agriculture and Rural Development: House Plants: Artificial Light