Try a farm and feed store that has a garden section if you have one in the vicinity. I got a huge bag of vermiculite there, along with sulphur powder. Hi Yield wettable sulphur to be precise. Both were very reasonably priced.

You had the questionable temps in the refrigerator, didn't you? I'm sticking with plastic wrap- but you have to use whatever works for you.

Linnea, I found antifungal powder at Pesche's on Des Plaines River Road & Rand Road in Des Plaines.

Mine were moldy too, so I washed them up and placed the good ones in a cedar barrel then covered them with moist peat moss and mulch since I did not have enough peat moss. They all did fine. I won't wrap them this year. My basement is too warm.

I know some people have good luck with peat moss. When I first tried dahlias some years ago they were a gift from a friend, and I stored them the way she did: a cardboard box with peat moss, sprinkled with water, stored on the floor of the basement. She said to open the box several times over the winter and sprinkle it again. I did it all, and while hers lived, as they usually did, mine were shriveled little nubbins. So I think there is no one right way, and the conditions under which they are held (humidity and temperature, the things that are harder to control) are probably more important than how they are wrapped. If I am lucky this year and have lots of tubers I will try several methods; as I don't want increase, just survival!

Odd, though: this year I bought all named varities, starting them indoors in March for earlier bloom. I have had much LESS bloom than on last year's cheapo-unknowns bought bulk from Sam's Club, and tossed in the ground willy-nilly. Bishop of Llandaff has grown well; the others, though the blooms are beautiful, have produced so few of them. It's September and Apricot Sorbet and Procyon have yet to open a bud. I have 9 of each of them: you'd think I'd see something. Half are so wimpy I don't think they'll bloom at all.

I don't recommend storing your nubers in peat moss.
It'll wick away too much moisture from the tubers during the storage period. They emerge in the Spring as little shriveled nothings. Go with the vermiculite.
DB

So far I can't find vermiculite. There's no farm stores in my area (I checked online) but I'll be in a rural area tomorrow. I checked by phone for that area and still can't find the vermiculite.

Linnea, I don't know if you are in Chicago or not, but this thread discusses other sources of perlite/vermiculite you might find it useful. Or perhaps you'll find some more rural supplier. Good luck! If all else fails, there's Home Depot or Lowe's.

Here is a link that might be useful: Vermiculite Hunt on another GW forum

I will never use peat moss again. I did several years ago, and lost everything. That is why I use a different method, based on the saran wrap method, but less costly, and I find more successful. Get some bulb dusting powder, and coat the cleaned tubers well. Then wrap them in recycled plastic grocery bags with the label written on the bags. Store the bads in a cardboard box or two or three. Place these in a cold cellar which does not freeze. It has worked for me for many years.

I admit, I got the idea from the saran wrap method, thinking that if saran wrap will work, why not the plastic grocery bags. They are free, and I can write on them as well with my "sharpie". I don't wrap the tubers as tightly as I would with the saran wrap, so the extra air I think has some benefit as well. I lost all my saran wrapped tubers last year, but lost none of the grocery bag wrapped ones. Be sure to dust them well with the bulb dust or fungicide. It does pay off.

jroot, I'm inclined to your method! Seems easier too. What is in your bulb dusting powder? Is that sulphur based?
Do you put more than one tuber in each bag? Last year I couldn't see any eyes (new to saving dahlias), so sort of cut at random. Since they all rotted anyway I never found out if I cut well or not. I'm more inclined to wrap the whole cluster and see if I can figure it out in the spring. The packaged tubers I bought new this spring were all clusters, not individual tubers.

Still no vermiculite... the thread mentioned above by poochella was about perlite (though I'd like some of that for next spring's planting too). But maybe I don't need vermiculite now?

I have most recently used Wilson's Bulb and Soil Dust which is a combination insecticide and fungicide for use before storage. The active ingredient apparently is Carbaryl 5% and Captan 5%. I am not sure what the rest is. Don't breath the dust though.

I put 4 or 5 dusted tubers per bag, but not all of one variety, just in case. Sometimes, if in a rush, I will put a cluster together, but it is NOT my preferred method. I usually trim off the skinny rat tail like tubers as well as the thin roots. Remember to keep a little (n about an inch or so) of the stem attached.

I finally found the vermiculite in small bags. I'm not sure I need it anymore for the dahlias, but I bought it anyway. I can always put it in soil mix.

But I'm still looking for the anti-fungal. I'm a little confused about what I should be asking for when I call around: sulfur dust or a commercial fungicide? I found liquid fungicides; but I need a dry one, don't I?

Jroot, where did you find your "Wilson's Bulb and Soil Dust"?

I got mine at a local hardware store. It is also available at the garden centres now. It doesn't have to be Wilson's, just a good preservative to fight off any mold and mildew which might set in during the winter without it.

Good luck.

Here's a place to find sulphur dust. I've used this same size bag on many tubers and it lasted over 2 years.

Here is a link that might be useful: Sulphur dust