i too am having a color fading issue, i potted up my dark red dahliettas and after a few days they have faded to orange.. any ideas?? what can i do to get them back the dark red i bought them as?
It may be a cold weather issue, or too much rain, and not enough heat. In proper growing conditions ( over a reasonable time period) they should always revert back to their original genetic form and show their true colours.
Soil conditions may be another factor. See what happens with hydrangeas.