Lovely (although all that bias would make me crazy)!
I would suggest a border of the darkest green you have in your blocks. I think that is the the darkest color (at least according to the way I see the picture on my monitor). It looks like a solid batik.
The rest of the fabrics are relatively light, and having the dark around them would make the center pop out and "sparkle."
Any type of pieced border, I think, would be too busy, and would compete with the subtle pattern of the blocks. It's busy enough (in a good way), and a busy border would just take away from it.