This is an old thread but since Joe has revived it, here's a bit more info that may be useful to someone. It makes a difference to the minimum germination temperature whether the seeds were stratified or not before planting.
Non-stratified daylily seeds germinate over a narrower temperature range than stratified seeds. From research on daylily seed germination published in the 1950s by Dr. Griesbach, for non-stratified seeds the minimum germination temperature was found to be 61F (16C). (The optimum was 72-77F (22-25C) and the max 91F (33C). If the seeds were stratified before planting, however, they could germinate at 50F (10C) or even lower.
The research article is this one:
http://www.jstor.org/stable/24...
