The Ilex verticillata, or winterberry, is a handsome, versatile shrub whose manageable size makes it perfect for specimen plantings. Nearly care-free once established, Ilex requires no pruning for the sake of its health. In fact, over-zealous spring trimming would go a long way toward ruining the naturally symmetrical appearance of the plant's crown. The best location for Ilex is a quiet spot where the low, spreading habit of its canopy doesn't branch out into your way.
Use loppers to remove any deadwood. Cut limbs and branches one at a time, just above a natural branching point. Always make your cuts crisp and clean.
Remove any damaged or diseased limbs. Don't cut or trim any of the old wood during the late summer. Resulting new shoots will need plenty of time to establish themselves before the onset of winter. No further thinning within the shrub's canopy is needed.
Use hand shears to touch up stray shoots which may extend beyond the natural canopy line here or there, if you think it looks a bit untidy.
Cut back the entire winterberry plant to several inches above the soil line in early spring to rejuvenate a leggy specimen.