I think it may be marginally hardy in a well-drained spot (one of those elusive places with perfect drainage but which stays moist all summer, right?) and with a good, light mulch around the crown. I've had good luck with wrapping the trunks of other cordylines (baurii, for instance) with coconut fiber and tying the leaves together over the growing point. When in doubt, I always keep a cutting or sucker inside for insurance.