Yes that should work (though I would not soak them unless they are really dried up) - warm and moist will encourage the eyes to pop, then divide them with a blade wiped with alcohol, and get them going as individuals. You can use a gallon size ziplock with some moist potting mix, close it up and put it somewhere warm (75-80- degrees) check it every few days.

I divide mine in the fall when I bring them in, and usually can't see any eyes, so just make best guesses. I try to leave a little bit of stem on each tuber. I get it mostly right, but there are always a few that never develop eyes.

150 tubers is a heck of a first try with dahlias - good luck with them !!

Thanks Mandolls. I will try the ziploc-potting soil route. See that you are also in WI. Are you already planting outside? I am in Kenosha, and am a bit nervous about the 20 or so tubers that I already planted out last weekend. Don't know what would happen to them with the rains we are getting... :(

I don't plant my dahlias out until the end of May. The standard rule is if it is warm enough for tomatoes, then its fine for dahlias. I am a bit further north, about an hour east of St. Paul.

Cold and wet encourages the tubers to rot. If you have good drainage in your beds you may be just fine.

I wake up my tubers early and grow them in pots under lights, so that my late planting doesn't slow them down as much. Some are so much slower than others, I have a couple that are 18" tall in gallon pots. Most are in 4" pots 6-12" tall, and some are just starting to get above the soil line. I am planting about 80 this year, about 60 different types. I don't have the space for more - but I say that every year, and then seem to find ways to squeeze in more. They get kind of addictive - watch out.