Whether you are sculpting boxwood (Buxus) into a perfect orb or simply shaping it a little, prune it in late winter and again in mid- to late June. For a graceful, natural appearance, trim boxwood by hand. Over time, boxwood often develops a leafy outer shell and a twiggy interior. Maintain a dense, leafy interior by increasing light penetration. To do this, annually thin the plant by snapping out 6-8-inch-long twigs by hand at major branches.