Would a Plant Grow Better Under a Green or Red Light?


As indoor gardens soar in popularity, so does the amount of misinformation about lighting techniques. One persistent rumor is that plants grow better under green light, however, green light is not conducive for plant life. Red light is the best light for plants to blossom.


Perhaps what some people refer to as green lights are the new energy-efficient, i.e. "green," LED lights. There is a difference between the actual color or pigment of a light and the color of the light spectrum that is distinguished by its wavelength and frequency. For example, a standard HID light would produce a predominantly red light in the spectrum, yet it shines as a normal white light. This is not to be confused with encasing a light with a red translucent plastic, which would produce a red-colored light. According to the light spectrum, blue or red light has the highest capacity to provide adequate lighting for growing plant life, not a light that is colored green nor a green light in the spectrum chart.


The main types of grow lights are LED, compact fluorescent, high-intensity-discharge (HID) metal halide and high-pressure sodium lamps. LED lamps are the most energy efficient and produce the least heat (which can prevent the air conditioning from being unnecessarily used). HID are efficient in that they produce a high level of lumens per watt. Fluorescent lights are full spectrum with blue as a prominent light. HID are primarily red light and deficient in blue light.


HID lamps are typically 24 inches by 12 inches, and range from 250 watts to 1,000 watts. Compact fluorescent lamps are usually 14 inches by 4 inches. LED lights are spotlights normally four to six inches in diameter.


Light in the red spectrum (not red-colored light) is most helpful for plants to bud and flower. Light in the blue spectrum assists plants with vegetative growth.


People generally use 25 percent blue light for most plant-growing purposes. To expedite plant growth, try 50 percent or 75 percent blue light. Use 100 percent red light to maintain plants that are past their main growth state and to promote fruiting.


  • ACF Greenhouses: Indoor Plant Grow Light Guide
  • Home Grown Lights

Who Can Help

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Keywords: growing lights, red light, green light, blue light

About this Author

Mercedes Martinez is an eco-designer focusing on renovations. She has a degree in interior design and a minor in architecture. Recently, Martinez has been enjoying exploring her writing skills that have developed her passion for design.

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