There are many varieties of holly, both deciduous and evergreen, and they are often used as specimen plantings or as screens in landscape design. Evergreen hollies should be pruned in early summer (pruning at this time allows any new growth at the pruning site to develop before the temperatures drop), and deciduous hollies should be pruned in late winter. How you prune the holly bush depends upon the variety of holly that you have and the shape that you desire. Reasons for pruning are to remove any dead, damaged, or diseased wood, to give the bush a formal shape, to thin to maintain an informal shape, and to encourage new growth.
Prune any dead, damaged or diseased wood as soon as possible. Make a clean cut at the point of the break, at ground level, or where the wood connects to the main stem. Where you make your cut is depends upon how it will affect the appearance of the plant. Diseased branches should be removed completely. You can do this at any time of the year. Small shrubs can be damaged during the winter season due to snow and ice. You will want to prune away these damaged branches at the first signs of spring.
Visually inspect your holly, looking for any wayward branches and any cross-over branches to thin out. The removal of these branches will maintain the natural form of your holly bush. Make your cuts parallel to a main branch so that the thinning is not apparent.
Shape your holly bush (if you desire a more formal shape) by removing/shortening the ends of branches to a bud or leaf node. Make an angular cut. Keep the base of the holly bush a little wider than the top of the bush.
Radically prune your deciduous holly bush. This will encourage new growth. Cut any stems that are thicker than your thumb down to ground level. Cut out old canes down to the ground. Snip off any growth that is gangly or grown out of the main body of the shrub. However, do not remove any more than 1/3 of the bush.