Here's what I see when I look at the blocks and the fabrics. I would make sashing with three strips of the fabric. Two dark and one light. I would make it into one piece of material dark, light, dark. Then cut and use as the sashing. I would alternate the blocks you have with another block too, like the quilt in the picture by Marykoch, but not necessarily the same block she used.

I think I personally would use the dark green as a sashing, it would really make the flowers just pop.