As Caroline stated... Dahalias go dormant due to the temp, rather than any need for rest.
When I've grown them... I had to protect them from deer and voles, but the lengthy season just made them happy.
Provide lots of light, keep them warm enough, and I'd expect to see flowers over the winter.
Ok... Just googled them... Native to Mexico, I don't reckon they go dormant at all if the temp stays warm enough.
