admmad said:
I think northern bred "dormants" will have a tendency to be unable to survive high southern summer heat stress rather than needing cold during winters.
So it is unlikely that daylilies hybridized in the north (without the input of southern-selected plants) would be good candidates for high heat southern gardens. Typically northern hybridizers would produce more "dormant" than evergreen introductions and so those plants would not grow well in the south but not because they are "dormant" but because they cannot handle the high heat stresses.
I would think that good examples of northern-bred lines that cannot handle high heat stress of southern locations would be introductions hybridized by Burkey, perhaps Hite, etc.
florange said:she gets hotter earlier in the season and it lasts longer at her place. In the summer she will top out at 92-94 while here on the beach we seldom get over 85. With your premise, I should be able to grow some dormants and she should not. Not true! That's why I truly believe that cold helps. Our soil temperatures will reach 81-82 during the summer. My friend's soil will get over 90 degrees where it gets full sun. When I have a daylily that isn't happy down here and it is going grassy, I send it to her. Usually it will straighten up and grow up there. I'm beachside in Volusia County (Central FL) and she is in Dixie County in north FL.