Different flowers have different leaves so I think different greens are going to make it more realistic (even different shades of the same green in one block) Don't forget to use the wrong side of the green fabric for variation in value. Somehow tie the blocks together...maybe with the same background; maybe use a same fabric somewhere in each of the blocks. It wouldn't hurt to use the same green in a few other blocks if you think it is right for that flower. Good luck and have fun! I LOVE applique!