Why not applique the strata onto a larger background square, then add sashing all around it in a coordinating color. Then just make as many as you need to make the size quilt you want. The edge on the quilt could be one half of a square. And add borders in the sashing color or a color from the squares. You could draw it out on graft paper to visualize how it might look. Lovely colors and a great job. Well done.