The best time to transplant a boxwood shrub is late winter, right before growth begins, or early fall, before the ground freezes. Boxwoods can also be transplanted in very early spring before new foliage begins to grow.
Boxwood roots, while they do not grow very deep, usually spread out wide, so digging a wide-enough hole is critical when transplanting a boxwood shrub. Before digging, mark a circle in the ground that matches with the drip line of the shrub's foliage. The hole for the new planting site should be slightly shallower than the height of the root ball, ensuring proper root establishment.