Why It Gotta Be Green???

The Green Knight is very, well, green! There isn't much more about him so far that we know about the guy. But, what we do have so far from is that he's super GREEN. Why though? Why is the Green Knight green? What is so significant about the color green when he comes to the Christmas/New Years kickback of King Arthur and his Round Table buddies? Is there symbolism with the color green? What are they? We shall discuss ;).