Gus, do you mean that the tubers are larger, or the flowers are larger?
Fwiw I'm in "northern" CA, zone 9b. Our last frost date is March 31st, but it's been a while since I've seen frost that late.
What I would probably do is just stuff the pots into one of our unheated sheds, and then pull them back out again approaching March 31st, fertilize them, and start watering. I really don't want to have to do any digging up of tubers if it isn't necessary.
