Back to the coloring aspect of this conversation, I'll share a bit of knowledge from a supurb hybridizer (Thomas Johnson, https://wiki.irises.org/Main/Bio/HybridizerJohnsonThomas) of Bearded Iris (which are also grown in full sun) that most likely will also affect our Dahlias. I grow oodles of Bearded Iris cultivars, many of which were new releases of his. Two or three years back I noticed coloring was off in many of the different cultivars' new blooms -- shading was less intense, seemed actually faded, so I wrote to him to inquire his thoughts. He explained that if there was some weather fluctuation that was out of the norm, aka early extreme early heat or unseasonable drops in temp that lasted - while the buds were forming, well before they open, that a fluctuation in expected coloration would be the result. So, my conclusion, is that it isn't just a more shady spot, for example, it could very well be attributed to some weather pattern affect on the future bloom(s). Further, it would then make sense, that & for example, a cultivar developed in the PNW will potentially color up a bit differently here in the Eastern-Southern states. It's not just soil, and not just a shady spot vs more sun. I think. Your thoughts?
