I can only add from my experience with Daylily pollen.
But I have thawed and re-froze the pollen many times without any problems or loss of fertility.
I should also add that the only success I had with shipping daylily pollen was when I shipped in the dead of winter, Wisconsin to Texas, all other attempts shipping in the summer were total failures.
My experience only, and heaven knows I'm no expert.
Ed Burton
