they can be pruned heavily or lightly for desired shape. prune after flowering but before mid-june so you don't cut off next years flower buds. if you want a round shape, i prefer a non-sheared appearance but this is up to the gardener. some folk manicure them into a hedge but i think they look best in a more natural, uneven form. try starting with the longest branches and work the shrub until you get to the size and shape you want.