Lacy blues- It is a beautifully placed quilt! I believe a brighter green binding would be perfect to balance the darkness of the sashing. If you add a 2 1/2" border sash and plan to do the brighter green binding, lay out a 1 1/2" strip of the binding color to see if you like the layer look. (i.e. quilt top, 1 1/2" bright green strip, 2 1/2" border sashing in same color as in quilt top, then the bright binding.) Seems like adding a lot when ready to see a finished product but sometimes the small bright strip ties in the binding color if it isn't a fabric used in the rest of the top. It is already an awesome top
