I can't give you an answer, but that sure s cool looking.

I have found that this happens a lot about this time of year.
My "Hollyhill 6 in 1" went tosolid red with one white tip from a yellow varigated one. Today I picked a "Wyn's New Pastel" that was a pinky carmel gold with 3 pastel pink petals at the bottom. Most likely the dahlia will return to being its usual color next year...unless it truly has created a sport. I think you have to cut the tissue where the sport is and propagate from that to preserve it.

MANY grower sites I have visited will tell you that a lot of bi-colors will pull one way or the other on a whim. Check out "Rebeccas World" dahlia - it may pull all crimson and little white or all white and no crimson and of course it is supposed to be half and half.

Have had the same thing happen to me on several dahlias in my yard. Next year I am going to try Court Jester from Hollyhill. It is said it will also pull more white or red depending upon ???? There is no rhyme nor reason to whether it goes all one color or the other - they just do.

I have several Purple Splash in my garden. Most of produce all variegated flowers like they are supposed to be, but one plant has lots of flowers that are completely or heavily purple colored. It's very interesting.