There is always speculation that someone will breed a blue dahlia. Over the years,
we done that several times but the form was not good enough to keep.
That is obviously a false statement but we have always been looking for some blue in our seedlings. Purple flowers seem to have a good chance as there is what I call a "blue" purple version of purple pigment out there. Another color that leans towards blue is lavender and a really a deep lavender flower when shown to a "non flower" person would call lavender "light purple" .
When I sample spots on purple and lavender flowers with photoshop it registers the relative amounts of red, green, and blue(RGB). I believe it is the ratio between red and blue that seems to influence whether we see any "blue" in a flower petal. I am not saying that the petal is blue but the computer uses values of red and blue to re-create the color of the flower. Some petals need more blue to re-create the color. It is not the absolute amount of blue but it seems to be a ratio and when the red value is less than the blue value the flower appears more blue.
I sampled the florets of a purple flower that is purple and not a "Maroon" purple but just a typical nice dahlia purple dahlia flower. The red number was always more than the blue number.
I sampled a lavender seedling and in the various samplings the blue value was higher than the red value. This flower does appear to be more blue than the purple dahlia.
Conclusion: If there will be "blue" dahlia it may be a version of a "lavender" flower. And we all knew that didn't we? For example, Worton Blue Streak, is said to be as blue as any and is lavender. I sampled a picture of B. Streak and it's red an blue values are almost equal but the blue value is very high. Our lavender flower has more blue than red in it' s petals but is not as high in it's value for blue. Blue Streak (in that one picture) has more blue pigment but also an equal amount of red and it is the ratio that counts.
Please do not ask for pictures. I do not want to post unverified, speculative pictures. The point here is that there is probably a pigment in dahlias that is more blue and we may be able to be breed a version that has more of it and also less red and maybe the flower would be blue(probably only "sort of" blue).
