FredL

Maineward, in the Spring you can probably do both, at least to some extent. I have found that in areas with pronounced seasonal effects, as you certainly are, collected trees can take alot of abuse in the Spring and still recover, something they can't possibly do at other times of the year. I've also found that pruning back of the top actually seems to help newly potted trees by reducing water loss (transpiration) when they are initially potted. Normally, root pruning for potting will also stimulate a burst of new growth, something you don't want to happen going into Winter.

My experience has been that potting Conifers in the Fall has been disasterous, though many Deciduous trees tolerate it pretty well. In the Spring, I've seen miraculous recoveries of trees I never thought would make it. My reading indicates this is because new roots which are formed in the Fall are very sensitive to damage from freezing.

If it were me, if at all possible, I'd wait until Spring, then prune both tops and roots when potting. This will be pretty stressful, so, best to wait until the tree is fully recovered before doing any more operations on it. This will normally, in the case of Junipers, mean one to three years. In general, trees do best with aoccasional major operations followed by long periods of rest rather than continual smaller operations without rest in between.

At least, this course of action is working for me.

Hope this helps, Fred