The phrase "extra greens" usually means having more money or more benefits than what is normally expected or required. It refers to having extra cash or additional advantages in a certain situation. Full definition
The only caveats here seems to be that some of these ingredients are not organic, and that this many ingredients may be too much for someone just looking to supplement with extra greens. (yurielkaim.com)
Get extra greens whenever you can — they're the best thing for you! (thebettyrocker.com)
Blend until smooth and add extra green powder and spinach as needed until you reach your desired color. (theglowingfridge.com)