For container gardening, assume you are two zones colder then you are. That is, if your spruce is hardy to zone 3 (which seems likely given its name), it should be fine in a container, as long as your container is winter hardy, too. (If it's in terra-cotta or ceramic, good chance the container won't last.)

To be sure though, can you put the container in another container and then insulate in between with mulch, soil, or styrafoam? Some of my iffy perennials have survived winter in their original containers with just covering the container in contractor bags (heavy-duty ply trash bags used by contractor -- can be found in Home DePot, Lowes, and the like), stuffed with old vegetation from last summers annuals, like tomato vines. Of course, I leave the top opened, to make sure they get some water during the winter.

I still would hope that folks will give you more answers, since I have no experience with large bushes and trees yet. Given that this forum is rarely visited/used, you might want to ask in the container gardening forum, a more active forum.

Thank-you for your response. I did post on container gardening when I noticed the lack of traffic here. I got a brainstorm idea on my own. I buried it in my compost pile with leaves and garden waste all around the black plastic container. I think it should work great. For a potted clematis, I did like you did, put it in another container with styrofoam . Glad to hear that worked for you.