I asked Dr. Keith Hammett PhD whether dahlias had hybrid vigor. He said that I was the first person to ask that question of him. He said "I will answer the question after I think about it. "
An hour later, I waited for his erudite answer. He looked me in the eye and said : "No".
I said this and that in response and again he said said "no" .
There is a genetic definition of hybrid vigor that is something that is very technical. From his perspective, dahlias do not meet that definition.
When breeding dahlias, you are incorporating the genes you want into the flower. When you outcross. the same trait in the other line may be caused by different genes or even a different set of genes. They may or may not be compatible with your flower. Staying within a line of breeding you have much better chance of compatibility. If you define "hybrid vigor" as "you will get a lot of unexpected bad and sometimes good results." then yes they have hybrid vigor. Our best results come from crosses within our own lines of breeding.
