Do plants grow better under sunlight or artificial light?

Answer 1

In general, sunlight is better for plant growth as it is intense and contains the full spectrum of electromagnetic radiation required for optimal plant growth.

Artificial light, if it is an ordinary room light, will only support low-light tolerant plants. Most artificial light sources (fluorescent and incandescent) do not provide the full visible light spectrum that is required by plants for optimal growth, this results in plants that are tall and spindly (etiolated) and sometimes discolored.

However, there are special lights with a spectrum that is tailored for growing plants. They have to be on for longer hours than sunlight, but as long as a plant is getting enough light-energy to manufacture its food, it will grow well. It doesn't matter whether that light is coming from the sun or from grow lights.

The downside to extended exposure to light is the plants metabolic functions operate twice as hard for the same amount of output. Recent studies have also highlighted some of the negative aspects of extended photosynthetic periods (extended light reactive period and shortened dark reaction period).

There are times when artificial light has an advantage.

Hydroponic gardening with artificial light makes it possible to grow plants in unreliable climates that are lacking in sunshine - think of the long "night" periods of areas of the northern hemisphere. In some places in Canada forage for animals is produced indoors during the winter months in artificial conditions.

Supplemental lighting is used in horticulture to produce plants in flower outside of their normal flowering period. For instance Christmas cactus, poinsettias, tulips, narcissus, chrysanthemums, etc.

Many houseplants grow better under artificial lamps, not because of the lights, but because it keeps them away from drafty windowsills!

Plants will grow better under sunlight; artificial light lacks the complete spectrum of light provided by the sun. You can purchase "grow lights" which have a special coating on the bulb to produce more light in the spectrum that plants need to photosynthesize. However, they can never completely duplicate natural sunlight.

Artificial lights are produced to help humans see in the dark, so they only need to produce light in the visible spectrum.