If I were to use a border (and it'll look great either way), I'd make a border the same width as the borders around the blocks. I'd use a lighter color, though, because if you use the same color as the darker green, some of the blocks would look like they have a wider border on one side. I'm OCD, though, & like everything uniform. Then I'd bind it in the darkest color of the block borders. Very nice quilt.