The only reason there isn't a dahlia forum is because there hasn't been enough interest yet.
We like to wait until there is a large demand for a new forum before we create it so that all of our forums are well used.
The [url=http://garden.org/forums/view/perennials/]perennial forum[url] would be a great place to get started! There are a lot of dahlia lovers out there (I'm getting my own little collection started as well! You are right- they are addictive!)
to ATP!