Even outside the color will look different in the first half of morning or second half of afternoon than at noon! It will look different if the sun is diffused by clouds or is is filtering through overhead leaves. It may not be the same in all seasons because the sun angle will be different. These are real differences to our eyes, and to the camera. A picture in a greenhouse with shade cloth may also be color shifted. I think all award photos are taken indoors and the light is usually variable from site to site and often far from what natural light would show. That is why the award photos can appear either “bluer” or ”redder” in color than what we see if we have the same plant.
Where you live, you might be able to get all of your pictures outdoors throughout the year to help your cell phone be accurate. I would try for a site that would let you have mid-morning sun shining from behind you directly onto the flower. The sun needs to be high enough so that you aren’t casting a shadow on the flower. I obviouslyl can’t do that in Minnesota when it is cold!