Maurice should be able to give you a better answer than me, but as far as I'm aware we don't know what the problem is with some "dormants" that reportedly don't thrive in hot climates. It may have nothing to do with needing cold but actually be heat intolerance. Or a problem with using up stored "food" during respiration during a warmer winter but having no foliage to replace that "food". Come to that, we don't really even know what is a "hard dormant", it's not an official term. Munson, in his book "The Daylily", described a "hard" evergreen as one that was evergreen and hardy, and a "soft" evergreen as one that was evergreen and tender. He switched the use of the terms hard and soft in relation to dormants by saying a "hard" dormant was one that needed a long dormant period and a "soft" dormant was one that only needed a month or less.
Over the years I've brought a number of daylilies indoors for the winter (spring sickness experiments) and it has been very rare for them not to start to grow as soon as they came indoors to the warm, even when brought in during the fall soon after the foliage died back. On that basis the majority do not have a "true" winter dormancy in any case. Any daylily can have dormancy induced by the environment though but the difference is that in a "true" dormancy a plant would require a release mechanism and would not grow immediately on coming indoors unless that release mechanism had been triggered (such as a specific minimum number of hours below a certain temperature). By "true" dormancy I mean what is described scientifically as endodormancy, environmentally induced dormancy would be ecodormancy. I think Maurice has probably explained this elsewhere so I won't elaborate here.
