That is beautiful and the border will add to its beauty. Be sure and let us see the finished project. I think two designs would be lovely and of course the leaves amd vines will add to the color and interject a new feature. I would think the border should be wide enough to "look right" with the flowers and vines. Sometimes I just audition until it looks right. Since don't know the width of flowers, etc., hard to guess for me. Very, very pretty.