I had lots of dahlias in pots at the end of last year, some grown from seed and the rest purchased as tubers. I stupidly decided to leave the ones in bigger pots outside, and moved the smaller pots only into my cold greenhouse.
I'm checking the pots today to see if there is any sign of life, but rotten tubers in most pots so far. At the allotment it's a similar story, only two out of six big tubers are putting out new growth, such a shame. That will teach me!