QUESTION: When do I prune my shrubs?ANSWER: Most gardeners understand that shrubs they expect to bloom this spring, notably pieris, azaleas, rhododendrons, forsythias, camellias and spireas, should be pruned after they bloom. Pruning while the flowers bloom to create bouquets is another option.But many ornamentals, including ligustrums, boxwoods, hollies and nandinas, benefit from late-winter pruning before the plants put out new growth in spring.Shearing certain plants, including Japanese and Chinese hollies, ligustrums, cleyeras and others with dense foliage, used as formal hedges is useful.It encourages an even amount of new growth that maintains the hedge effect. This is where you use sharp hedge clippers to cut back the plant to the chosen height and width.Do not cut off more than one-third of the plant. Still, give the plant room to put out new growth without running into sidewalks, driveways or adjoining property.Shearing, however, is not good on plants growing solo, particularly boxwoods. It creates an unnatural look popularly derided as "Meatballs." There is a better choice.Thinning is one of the most useful pruning skills a gardener can possess. It is particularly useful on deciduous shrubs that produce long, arching stems that create graceful fountains of flowers.Thinning rejuvenates older plants by letting sunlight reach the interior and making space for new growth to rise neatly from the base.Boxwoods will benefit from this technique because it lets light into the interior and encourages leaf growth below the tips of the stems.