Maybe ask this question on the conifers forum. Is your soil frozen? If not, I guess the usual precautions would be in order, try to get a good mound of soil with the roots, transplant carefully, water well, etc.

As to when to move back, not sure, but anytime before they start growing in spring might be good. If it turns cold, snowy and frozen, then you probably have to wait until after the snow melts and things thaw out in spring.

Not an expert, I just see that no one has answered this so I thought I would offer my two cents.

Thanks for the help.

I agree with Glen 3A - actually, many people dig up evergreens with root ball to use as "living Christmas trees" - then they replant them. Keep the root ball well wrapped - replant as soon as possible and certainly before warm weather comes. If necessary - plant them temporarily somewhere rather than leave them above ground as warmer weather begins. And then water, water, water - that is the key with evergreens - all through 2005. My neighbours moved a huge blue spruce in summer to make room for a new pool - about 15 foot tall! They figured they had nothing to loose. With much water, it survived!

Do you have a place where you can keep them that would be cool and provide just a bit of light? Oh, and the air should not be too dry...
A couple of years ago, I approached a local mall as to what they were going to do with those lovely Hollies and Blue Junipers they were using for their holiday decorations. In January, I managed to get 5 Blue Junipers and 3 Hollies from them at no cost. They were in large clay pots, but I took them out and placed them in larger pots with very good moisture retentive soil.
In January, our soil is frozen rock solid, so I decided to keep them in our basement. Our basement stays around 5 degrees Celsius all winter with a humidity level around 60%. I chose a spot where the sun coming in the windows never directly went on the schrubs/trees. I kept the soil moist, but not soaking wet. In mid-February, I noticed the soil was frosty because they were by the door... Not to worry, I figured this would have happened in nature, and they had about 6 weeks to settle.
In the end, I lost one Holly. The two others lost nearly all their leaves, and the Junipers looked a bit dry by the time we planted them outside, but the fresh air, good soil, and TLC brought them back and they are lovely with a slight snowfall on them today!!
Nicole.

Wow, Nicole, you really scored! What a great idea!

I've read that they don't survive if the root is bare, so keep the soil ball intact. And water a lot all year, even in winter.