Green is used in hospitals because it's thought to be easier on the eyes and to help lower the stress levels of both patients and health-care people. 

In recent years, green has signified hospitals (think about the phrase "looking a little green"), and some hospitals are now switching to cool blues. 

Yellow-green, the color of sick plants, is now associated with sickness or impending death.

Green is the most refreshing, restful color to the eye.  The word "green" comes from the same root as "grow," so green symbolizes that which grows:  rebirth, regeneration, the renewal of life. 

Indian mystics see green as the marriage of balance and harmony, the ray that bridges cause and effect.

In heraldry, green indicates growth and hope. 

Green is also associated with naivete and jealousy. It conveys a sense of restfulness and adds balance to interiors.

To the Japanese, "midori" (green) is seen as the color of eternal life.

Traditionally, green has been used in libraries and studies as it is believed to create a contemplative background.

"In music, absolute green is represented by the placid, middle notes of a violin." -- Wassily Kandinsky