While I don't have any experiments, I have experience. Daylilies have been grown by my family in central Oklahoma zone 7a since they arrived here in 1889. Hundreds of cultivars have been grown for the past 75 years. One reason for growing daylilies is because they survive and reliably bloom every year. We have daylilies from all over the USA. and from hybridizers in all growing zones. Our summer temperatures are as hot as anywhere except the desert southwest. It is rare for us not to reach triple digits F each summer. Our average July high temperature is 96F. We do get 4 seasons and regular winter freezing temps.
We currently grow about 600 registered daylilies and well over half are dormant. I think the dormants are more reliable than the evergreens. I have Florida evergreen cultivars that are registered at 35+buds that will have between 2 and 10 buds in my garden. They will only bloom every other year and never increase. The hard dormants will bloom every year with normal bud counts and increase to nice clumps in two or 3 years.
I am generally speaking based on foliage habits but looking at our daylilies this year, the dormants were just tips above the ground two weeks ago. Our temps have been mild with highs in the 50's, 60's and some 70's. Nights are still in the 30's and 40's with some freezing temps each week.. The evergreens and semi-evergreens look about the same as they have all winter while the dormants have grown 6-8 inches tall in two weeks.
I have a species -Hemerocallis dumortieri that blooms mid April almost every year. Our last freeze average date is April 1st. It will go from dormant to bloom in a few weeks. No other daylily will typically start blooming until late May about a month and a half later.
Maybe I don't grow the cultivars that can't take high temps but I am not at all particular when purchasing plants. I don't even think of the foliage habit of D/SE/E. I just buy based on what I want in a bloom. I have purchased plants from Florida to Wisconsin and all growing zones between. The only thing I try to avoid is getting plants too late in the spring. But sometimes I just want to buy from Michigan or Wisconsin and they will ship late for my area. Last year I planted all my late spring order in the shade. Now some need moved to a more sunny location.
I have never moved daylilies in February before, but this year the past few weekends were so nice that I have been gardening like it is April. I moved 20-30 daylilies in February.
Terry
