Sometimes a camera can give that color all by itself when simply set to "auto", with no color manipulation at all. I have had it happen to me when photographing Absolute Treasure at various different light conditions.
Same flower, same camera on auto setting, different times of day.
Obviously that last one is way off! That's why it's important to view as many pictures of a cultivar as you can find before choosing to buy it. And that's also why registered names are important! You can always Google a registered name, followed by the word "iris" and then when you get your search results switch your browser to "images." You can also do a name search in the NGA iris database and then scroll down to see all the images for that cultivar.
One of the reasons that different times of day affects color is that if the sun is directly overhead, its rays are coming through a thinner section of atmosphere than if the rays are slanting through the atmosphere at dawn or dusk. The atmosphere acts somewhat like a color filter. So you get more or less filtering out of certain colors depending on time of day. Old, retired optometrist speaking here.