new japanese iris...better in pots ?

I'm getting a couple of starts of JI. Now positive where I want to put them....would potting them work good for the winter and then slip out the total root ball and ease into place next spring ?

It's my understanding that they require a cold period. Doss would love to grow them but her winters aren't cold enough. Since the big nurseries ship in September I'm sure they wouldn't do so if there wasn't enough time to get them acclimated to the soil and have new roots grown before winter.

I'd plant them in manure, give them lots of mulch, sunshine and water.

I just transplated a few hundred of them and that's what I gave them.

Thank you Pirl.