Earlier we discussed why prune as well as basic tools needed. Below you ‘ll find some useful instructions from the head gardener at Cylburn Arboretum on winter pruning:
Early in the winter season, look (and feel) your boxwood. If they are thick at the surface, but bare below, December is a great time to encourage heath (and lower green growth) by “making holes” to add more light and air circulation. Cut select stems down 8-12”—to where those stems originate from other branches). Avoid simply shearing, which results in thick growth at the surface, excluding light and air (so that the inner plant becomes bare). You can find an excellent reference from Lynn Batdorf at the National Arboretum right here.
Later in the winter season (February and March), examine your other woody plants. Eliminate dead branches (you can confirm a branch is dead by scratching—it will be brown or tan underneath, rather than green—but don’t go scratching every branch—look for other changes, such as color, or absence of vibrant buds first). Remove crossing branches (here you might have to decide which of the crossing branches to eliminate—look at overall form and health of each branch). After removing dead and crossing branches, the remainder of your pruning should be based on the growth habits of the particular plant, and how you would like the plant to fit within the rest of your garden.
(And for those of you who missed the wonderful world of Amelia Bedelia, here’s how she would prune a hedge)