splinter

Are you in Littleton, just South of Denver? I believe you're in Zone 4/5 - just about 5/6. I am in 5/6 area, and keep my Junipers in an unheated, closed-in porch in the Winter. The main thing about having a potted tree outside, is you don't want the roots to freeze and stay frozen. Since yours was in a store, it's probably used to a warmer temperature, and is probably not going to do well just all of a sudden going outside into snowy conditions. If it had gone through the "normal" seasons, it would be fine outside if the pot was covered with mulch, protecting the roots. Unless you really keep things humid, it will dry out too much in your house. Be sure and keep it well misted.

Happy bonsai-ing!
Marsha