I'm not looking for cold hardiness as for overwintering but rather the minimum spring temperatures it can take as to not have it set back or die.
Above feezing, probably in the mid 40sF.
I wouldn't put that one out until the temps are reliably above 50 at night. It's a picky one.
Has anyone tried overwintering this one in the ground in Zone 9? I have a few nice large ones and will try to leave one out over the winter here.