Do not even think about re-planting them in the ground in Michigan. They will be ripe enough to store if you dig them about September 15th and would not benefit at all from being replanted. And the risk of a killing(kill the tubers too) frost is too high. It is a total myth that dahlias need a frost to go dormant for storage. They are plants native to the mountains in Central America where it does not frost and they go dormant there during the winter.

I had to dig mine early one year because I was leaving the country for three months. I think I dug them in early September, and stored them as I usually do with no real issues the next year.

Thanks for the thoughts, looks like I better get to work soon!

Michigan has great Dahlia societies and Fabulolus growers

Mid Michigan Midland has huge dahlia gardens