This is a answer I saw in the houseplant forum. This is my first year so I am trying to figure out what to do with mine also.

'Dig and Store caladium bulbs before frost. (I think November might be waiting a little late) Remove foliage, dust with a fungicide and store in a stocking or onion bag (for air circulation) where the temperature is near 60ú.'

So you wouldn't want to put them in any kind of medium. then it recommends that you start planting them again in March. continue 'til July.

Thanks Marquet, I asked over on the Balcony Gardening forum after not getting any answers here. (It is frosting here already). I have dug most of them out of their pots, and have a few small ones yet to get out of the ground. Someone over there suggested perlite, and another suggestion was packing peanuts. For air circulation. We are not getting frost again for a few more nights, so I will wait for a few more answers. If there are any more. I may just hang them in an onion bag, in my basement.
Thanks again,
Leslie

Man I just put them under my sink till march. They sprout by themselves when I bring them out again and put the pot in front of the window. If you think about it- this is what happens in nature anyway- no special treatment- no perlite or chemicals. But maybe this is because I have mine in pots indoors- leaving them out in the garden during winter would kill them. I like the onion bag idea- maybe I'll do the same. The pots have no drainage holes and the soil is probably too salty by now anyway.