Unlike many hollies, winterberry (Ilex verticillata) is a deciduous shrub that produces plenty of red berries through winter, although its foliage is gone. Grown in U.S. Department of Agriculture plant hardiness 3 through 9, winterberry reacts well to a good trimming annually in late winter or early spring. At pruning time, you should remove approximately one-third of its branches, which grow from the ground rather than from a back, to maintain its shape and size under control and to encourage fresh, new growth that will subsequently create the berries.
Stand back about 10 to 15 feet and then inspect the holly. Search for branches that stick out and are not uniform with the other branches. Cut the side sections off to the ground with a sharp pair of pruning shears.
Search for stems that crisscross or rub up against each other; those branches can lead to injury to one another punctually. Cut off among those branches to the ground with your shears.
Examine your winterberry to look for branches that are dead, weak and spindly. Cut them to the ground. Then look for crowded places, which are unsightly and limit sunlight exposure to the center of the shrub. Thin these crowded areas by cutting a few of the branches to the ground.
Remove branches that are heavier than one inch in diameter; those are your oldest stems and will not create as much new growth as your latest stems.
Stand back 10 to 15 feet again, then prune branches across the bush so the winterberry holly still maintains a uniform appearance. Remember that in all, you shouldn’t remove more than one-third of all the branches at pruning time.