The Light Spectrum

• Light is divided into colors, which are based on the size of wavelengths. Long wavelengths are visible to the human eye as red; shorter wavelengths appear blue or violet.
  
  

Effects on Plants

• Certain light wavelengths have more of an impact on plant growth than others. Yellow and green rays provide little benefit to plants. Red and blue wavelengths provide the largest source of energy for plants.
  
  

Artificial Lighting

• Natural light provides the full spectrum for plants. Artificial lighting for indoor plant growth must be carefully selected. Incandescent bulbs provide plenty of red light but not enough blue. They also operate at high heat levels, which can damage plants if placed too close. For best results, use fluorescent tubes in combination with as much natural light as possible.