Ckava!!!
I am not an expert by any means but if you look at the pictures of the daylilies in the database you will definitely see that they can vary in color and size in everyone's gardens. I would have to think soil is a factor for sure. Everybody's soil and mineral content in their soil has got to be different and that certainly can have an impact on the color of the bloom. Light for sure has an impact. If a daylily is in the sun all day as opposed to a daylily that is in partial shade all day that definitely makes a difference in growth habits. Daylilies really prefer full sun but I do have a few in shade that do well for me too. It all depends on each individual cultivar. As for temperature, most daylilies open much better in warmer weather and those that have ornate edges do better in heat. A lot of daylilies do not open well on cold mornings. I will let someone else chime in. I hope this helps a bit for you.
