Boxwood is very easy to propagate. In the spring, take stem cuttings, 6 inches in length, and remove the lower inch of leaves. For best effect, group five to seven stems together, as pictured, to resemble an entire plant. Plunge this group into soil that has been amended with copious quantities of peat moss or leaf mold. Pack the soil firmly around the stems. Keep the cuttings moist, and you will have new, rooted plants in about six weeks.
Source : From Parking Lot to Rose Garden