I think it needs sashing, but I don't think the yellow lets the blocks shine. They seem to blend into the sashing. The blue is too dark in my opinion, I would go with a lighter color. That will make the blocks stand out. Just my opinion, and I'm partial to the green in the blocks also the white in the blocks with a kinda bird footprint pattern would look nice. Sorry to sound so critical, I really like your blocks and the fabrics you have chosen.
Sue