Prune away any dead, broken, discolored or diseased foliage and branches. Place cuts down to a point of healthy tissue but not down into bare wood, if it can be avoided. Position cuts just above a lateral branch or leaf node. If an entire branch is compromised, cut it off from the trunk just outside the slightly swollen branch collar.
Reduce the spread of the hedge or tailor the shape by trimming off the terminal tips of the branches and shoots with long blade scissor shears or electric hedge trimmers. Follow the natural form of the plant, but keep the lower portion of the hedge slightly wider than the top to ensure good sunlight coverage to the lower area, preventing defoliation that is often permanent. Trim judiciously, removing only enough live tissue to keep the hedge in bounds.
Collect all the cuttings and loose debris from inside the canopy and any that falls to the soil below the hedge. Pathogens and pests can breed in decaying material, so spirit it away immediately after trimming.