Why is my tongue greenish and dry?

Dehydration: A Dry tongue can indicate that you are dehydrated. Caffeinated drinks are frequently at fault since they act as diuretics, encouraging your body to release more water. You should be drinking 6-8 cups of water or noncaffeinated, non sugary liquids daily. The greenish hue is probably due to mouth bacteria which become more obvious when the mouth is dry. If the green color persists, talk to a Dr.