@Seedfork
Wouldn't the oldest seedlings have a growth advantage over those that germinated later? Breaking dormancy and germinating first would seem to possibly give them an advantage in the beginning that they might not be able to sustain later. Also, might not genetics also be a factor? It may not be present in daylilies, but in cattle early, fast growth is a trait that can be selected for but is not distinguishable among mature cattle which end up similar.
Just thoughts. I like to stir the mud up sometimes and see how it ends up settling back down :).
