Ryan Williams, our member from Logan was kind enough to type out his method for storing his dahlia tubers. The plastic wrap method is in Mark's book, The Dahlia Diary. Let Megan know if you need a copy.
Ryan and Julie William's Method
Storing TubersOnce they are dug, washed, and devided I store them in zip-lock bags. I use the gallon size so I don't have to use so many but any size will do. I poke several holes in the bag so they can breathe. I do it with a board that has lots of nails sticking out so I can poke all the holes at once but a pencil or anything else works fine. Some people dust them with sulfer or dip them in a solution of captan which is a good precaution but I usually don't. Hopefully that doesn't backfire on me someday. As I seperate the clumps I can usually put one clump per gallon bag. Some varieties won't fit in one. If I only have one plant of a paticular variety I split it up into two bags just as a precaution. If one bag goes bad I don't lose the whole variety. I then put in some vermiculite, just enough to cover the tubers. Maybe two cups (I am not sure exactly I just put in what looks good to me.) Then I put the bags into a fridge that is set at 40 degrees. Any cool dark place will work fine. I check them several times during the winter to make sure they are happy. Every once in a while I will see some mold show up in a bag of tubers. If I see mold I take the tubers out and make sure they are not damaged. If they are I toss them and spray the bag with an anti-fungal. Maybe if you dust them in sulfer first you won't even have to worry. I don't ever have much of a problem. It may show up in a bag or two but that is usually the extent of it.