based on my understanding of the subject. Green witches are Druids that listen to trees and summon the power of nature to their aid. The power of a druid should not be reckon with. I tried pissing off a druid (Rare these days) and then the next day all my IMPORTANT herbs DIED. and then my favorite tree which I get knowledge from, Died. I was mad, I casted an elemental to take care of him. A week after that, He wen't to a hospital. LOL. I don't use dark magick unless I have to, its called defense.
Read the 3 books and you will know what it is to be a greenwitch in a since at lest. Try to learn every thing through nature and abide the laws, you can read but i think that inless it is your path than do not wory