Wow ! That is gorgeous ! Great job ! I just love it . i would lay a piece of the green like the color of the vines around it and see what that would look like . If it did not look good then I would go with white.
OMG that is beautiful. Sounds like I'm in the minority but I'd pick a light color to bind it. Kinda like putting a frame around a piece or art and your quilt is surely a piece of art.