Abstract
Light-emitting diodes (LEDs) have a narrow light-emitting spectrum, enabling them to focus light on
plants with the precise amount of required wavelength of light. Today, many plant factories are growing
vegetables with LEDs as a lighting source. Controlling light environments using the monochromatic
light of LEDs in plant factories might produce high quality vegetables, for example, leafy lettuce and aromatic
herbs, with high contents of nutrient or aromatic components. Such environment control can lead
to medicinal plants with rich pharmaceutical ingredients. This report overviews the historical developments
of plant factories in Japan using LEDs as a lighting source in Japan and describes the possibilities
of technical developments in the near future
