i would just attach the rows to each other as they are laid out. that gives you 4-strip borders between all the main sections of the blocks.
my habit is to pick one of the colors from the blocks and make a narrow inner border of that color. about an inch wide.
after that, i'd add at least 3" of something. i'm "lazy" so would probably add a solid-strip border, but you might consider a string-pieced border using any scraps you have left over.
if i pieced the wider second border, i'd tie it all together again with another 1-inch solid-strip border.
i'll bet you get lots of good - probably better - suggestions over the next day or so. :-)
p.s. - it's pwiiiiidy :-)