What a fantastic quilt. Wish I could see it in person. I would add a 4" border if you really want it to be larger, as another row of blocks would be quite a bit of work--you are probably burned out from getting this far. Color for the border? I would choose a dark tone on tone gray.I think a green border would not look good, but I realize that sometimes colors don't show up true on a computer screen. Your blocks look blue gray to me not green. Actually they look like that civil war blue color. If u know what I mean?