The color green has had quite an evolution in meaning over the years. The color refers to the naturally occurring color in nature but has much different connotations these days. Green has taken on both positive and negative connotations.
Green is often associated with nature, freshness, and a healthy
environment. With American culture pushing so strongly for a healthier
society and world, the phrase "going green" was coined to encourage such
actions. "Going green" can refer to a number of intentions though: if
one recycles, drives a Prius, turns off lights when leaving a room,
grows their own vegetables, becomes a vegan, etc. Any attempt to
preserve the natural environment.
The island of Ireland is also associated with the color green for its lush valleys and farms, even though their national color is royal blue. What people don't realize is that green is associated with Irish Catholics and St. Patrick using a shamrock to teach the Holy Trinity. Though as Americans, it's easier for us to think leprechaun > green suit > shamrocks > Ireland. And no differentiation between Northern Ireland and the Republic of Ireland, mind you.
Green is also associated with marijuana and even the slang term for cannabis depending on who you talk to. One obvious reason is that the plant itself is green, but has become a very large commodity in Colorado and Washington state.
The color green is also associated with jealousy, greed, money, and being nauseous. Most colorblind people are affected with red-green color blindness where they have trouble distinguishing between reds and greens.
World Wide Opportunities on Organic Farms (WWOOF)