It had very little mulch, if any. But it was up against the white cement wall of my garage (not attached to the house). It was right in the line of water dripping off the roof, but I guess I have good soil drainage.
I was surprised this spring when I saw one comming up, I guess I missed it last fall, I did not mulch much there until feb when they were calling for a hard freeze and some of my plants were comming up then I heavily mulched with straw, but we had 3 ft of snow before that guess it kept it mulched. It is doing just great.
I just dug up two volunteers from last year too. (One I didn't necessarily want, but I got it back now) We did have a very cold snap, for here, of 8-10 degrees in December and a hideous amount of rain in November/December/January, but the tubers were preserved enough to grow, even though many parts of them were mush. I replanted them in a new location after snipping off the bad parts. A dahlia is a terrible thing to waste...