In planning for my boxwood hedge, I chose Korean boxwoods (Buxus microphylla 'Koreana'), specifically, partly because they are hardier (to planting zone 4) than most.
Even so, it is said that the leaves of Korean boxwoods turn bronzy in winter (in cold regions). I cannot vouch for this yet, because the leaves on mine stayed green during their first New England winter. I had purchased them in late fall and temporarily "planted" them in the ground, pots and all, to over-winter them. However, that winter (2005-2006) was an unusually warm one. In addition, I sheltered my shrubs, and I watered them whenever there was a thaw.
You can make a shrub shelter for your hedge by modifying the steps I lay out in my tutorial on providing winter protection for shrubs.
I also chose Korean boxwoods for their look and growth habit. They're a slow-growing, compact shrub (2' tall x 3'-4' wide at maturity, if left alone) amenable to pruning, and they bear the classic small, rounded boxwood leaf (microphylla means "small-leaf").
Korean boxwoods are a sun plant and should be watered regularly throughout their first growing season. If you plant in early spring, hold off on both fertilizing and pruning until June. The nursery from whom I bought my Korean boxwoods recommended the slow-release fertilizer, Osmocote.
In Step 9 I'll discuss the subject of spacing hedge shrubs....
