That "big root" is what stores the food for next year's plants. You should notice a nice growing tip on the tubers. I'm glad to see that you have cleaned the tubers. Now you can trim off those small roots, let them dry for a day or so. I always dust mine with some bulb dust ( fungicide), and them wrap them up in old newspapers, and then in a cardboard box. About April, I start the plants up again in nice new soil. The growing tip should be much more noticeable at this point. Here is a link that might be useful: Check out this links

If the plants are well grown and hardy, I leave them outside. We have a reliable snow cover, but very early spring can be critical. I tend to worry if we have a January thaw followed by rain. If the plants were expensive, are immature, hard to replace, etc., I overwinter them in an unheated house with a frost blanket over the plants and opaque plastic covering the house to keep the light out. We don't have great luck overwintering plants grown in soilless mix. Hope this helps.

Thank you for the info. I like "easy keepers". I've killed more than a few dahlias from improper storage. Boy, you aren't kidding that they are slow to come up. I waited and waited and waited but since I had heard they were slow I put them outside and left them. About the time I thought that those things must have rotted here came one. One out of three bulbs, that's OK, they were cheap. About 2 -3 weeks later a second one came up. They were really striking. I'll definately grow these again. Thanks much. Maria

The real question has to do with the low temperatures the plants have already been subjected to. Even though Alberta spruce is listed as Z4 hardy, roots can be killed when they are being grown in pots. The thermal mass present in the ground is absent in pots and the temperature of the planting medium can fall low enough to kill roots. The subzero temperatures of the past week may well have already been too much. I would certainly keep them out of direct sun and wind and be very careful not to over water. I'd opt for the garage as long as it's unheated. Extreme cold combined with high winds can so dehydrate Alberta spruces that they develop large brown patches. Outright death is more unusual. Erecting a burlap screen to protect from sun and wind is a good idea. Don't wrap burlap directly around the tree, though.