Multiple cultivars of various spruce species (Picea spp.) offer a relatively small size and slow growth habit that make them acceptable for cultivation in containers. One widely available dwarf spruce is the dwarf Alberta spruce (Picea glauca "Conica"), found in U.S. Department of Agriculture plant hardiness zones 2 to 6, which grows no more than about 3 inches per year under ideal conditions. It is only occasionally necessary to prune a dwarf spruce, but this rare pruning does help to keep a potted spruce attractive, addresses certain problems and maintains the spruce at the desired size.
Soak any pruning tool in household disinfectant for five minutes between uses; and, if you are making cuts to remove portions of the spruce that may be diseased, after each cut. Following soaking, let the tool air dry or rinse it with clear water before making the next cut.
Cut or, if the tips are tender enough, pinch branch tips back selectively where a certain branch is growing out-of-bounds, or to encourage branching and bushier growth in that area. Remove only a few inches from the branch tip, and do not make any cut beyond where green needles emerge from the branch, or the branch will not recover. Make the cut where you still see plenty of green needles, and try to position any cut just above a bud or node.
Prune off any dead, damaged or diseased branches as you notice the problem. Make any cut a few inches below the bottom of the problematic area if you still see green needles in that area. If you have to make a cut below the green growth, prune the branch back to a larger branch or the main trunk.
Monitor the potted spruce, looking for the appearance of any prominent, overly vigorous new shoots that are thicker and producing larger foliage than other shoots on the spruce.
Cut the large, vigorous shoot off just below where it emerges from the spruce branch or just outside the main stem. This is a reversion to the species form and must be removed promptly to maintain the spruce's dwarf form. If you wait too long to remove it, you'll likely have a noticeable gap in that area of the spruce when you finally prune off the vigorous growth.