Plants need light for photosynthesis, but the light need not be from the sun. Lights with outputs in the red and blue ranges of the visible spectrum are effective for growing plants.
Incandescent light from a standard Edison-type bulb is not good for growing plants. The light is too far in the red end of the electromagnetic spectrum, and too much energy is wasted as heat.
Standard fluorescent lights do support plant growth, although they are not optimized for photosynthesis. Newer T5 fluorescent lamps are excellent for plants.
Metal Halide Lights
Metal halide lamps are high-intensity devices with a strong output in the blue end of the electromagnetic spectrum. Metal halides are good for promoting vegetative growth.
High-intensity sodium lamps have an output shifted toward the red end of the electromagnetic spectrum. They are good for promoting flowering.
LED lamps are expensive to purchase but economical to operate. Red and blue LEDs can be combined to provide a range of outputs that are effective for promoting all stages of plant growth.
- Artificial Lighting: Powered by the Sun
About this Author
Philip McIntosh has more than 30 years of experience as an equipment engineer, scientific investigator and educator. He has been writing for 16 years, and his work has appeared in scientific journals, popular science magazines, trade journals and on science and technology websites. McIntosh holds a B.S. in botany and chemistry, and an M.A. in biological science.