Why bring the plant inside? Alberta spruce goes down to Zone 3. You can plant them outside... Or is there not enough room outside?

You may wish to go to the tree forum to ask this question. If there is a reason for bringing them inside, such as you have to leave them in the pots, perhaps someone over there will know.

I've kept a potted dwarf alberta spruce on my front steps for years. I kept one going for quite a long time, though it eventually died. I suspect it got too wind-burned. I replaced it last year just before Christmas and that one lived through the winter, though not without the loss of a couple of branches. It would probably do better in a more sheltered location, but considering how inexpensive they are to buy, I just take the risk and will plan to replace it again if it croaks. I need to remember to water it occasionally when the temp goes up, and it probably wouldn't hurt to spray it with one of those anti-dessicant sprays. Spiderman4, I assume your planters are 2 feet square--that certainly sounds big enough as long as they drain and are made of a weatherproof material. My pot is fiberglass, and isn't quite that big.