It would not be very difficult to produce a seed-based daylily strain that had a reasonably uniform appearance. Older strains or varieties of vegetables and flowers (some of the 'heirloom' varieties) are open-pollinated varieties and quite stable and uniform. A daylily seed strain would be basically the same as an open pollinated heirloom variety.
Although not difficult it would take some time. In annual vegetables and flowers one generation is one year or if one arranges to grow the next generation in the other hemisphere then it is half a year. It would probably require five or six consecutive generations to produce daylily seed strains that conformed to the rules of distinctness, uniformity and stability that allow the registration of named seed strains. That might mean as long as 18 years (or longer) or as few as five or six years in warm winter locations such as Florida.
It would be useful if the daylilies chosen could be successfully self-pollinated. That would making achieving the uniformity easier/quicker although possibly with the problem of the loss of some vigour.
