There are many, many factors that contribute to that. Some flowers are more susceptible to color changes than others. Things that affect flower color are soil, temperature, location, weather, time of year, early or late bloom on the same plant…pretty much everything. And some Daylilies appear to be completely unaffected by any of that, looking exactly the same in every yard.
In my gardens, blues and purples are pretty bright. I have a high acid content in loamy soil that has a minimum of red clay. The same flowers might look reddish in Southern gardens.
I have one flower, Country Vista that is literally a different shade every day that it blooms. It's clearly highly affected by temperature and light. I know stability of bloom type is a desired trait at Daylily shows but I love the surprise factor of a bloom like Country Vista.
