The color green is universally associated with nature, but can also be tied to luck, energy, fertility, springtime, wealth, envy and in some cases even nausea.
Green is the most restful and soothing color for human eyes, and is thought to promote feelings of calmness.
“Green thumb” “The Green-eyed monster” “Green with envy.” “Green around the gills” “It’s not easy being green.”
“The eye finds a physical satisfaction in green. When the mixture of the two colors which yield green is so evenly balanced that neither color predominates, the eye and soul come to rest on the mixture as if it were something simple. We cannot and will not go beyond it. Thus green is often chosen for rooms where we spend all our time.” — Johann Wolfgang von Goethe, “Theory of Color,’ 1808 in Goethe: The Collected Works, volume 12: Scientific Studies, edited and translated by Douglas Miller, 1995