I recently planted a pyramidal-shaped holly bush, and the lower branches are pretty bare. Can I prune them to encourage new growth? -Judith
Holly bushes can lose leaves for a number of reasons, from diseases to environmental factors such as light, water, and temperature. Some of the most common causes include:
Pests or Disease: The first thing I would recommend is a thorough inspection of the remaining leaves, to see if there are any signs of insects or disease such as spots, shriveled or discolored leaves, bark damage, or galls (strange-looking growths). Some diseases, such as leaf blight, can spread by water splashing up from the ground, which makes the symptoms worse at the bottom of the plant.
Overcrowding: If the lower branches were bare when you bought it, they may have simply been too crowded at the garden center and those branches didn’t get enough sun. Or, if hedgerows are planted too close together, the upper branches can block sunlight from the lower branches. Bare branches can also happen when bushes and hedges are over-sheared, which causes thick growth at the edges that blocks light and air from the interior of the plant.
How to Prune Holly Branches
If your plant is otherwise healthy, or if you’ve successfully treated any pest or disease problems, follow these tips to give your holly a strategic pruning that will encourage the bottom branches to fill out:
Remove Dead Branches: Go ahead and completely remove any branches that are completely dead. The best way to tell is to lightly scrape off a little bark with your fingernail – if it’s green underneath, the branch is still alive; if it’s brown underneath, it’s dead. Dead branches will also be brittle and snap easily.
Pinch Back Bottom Branches: Very lightly trim or pinch off just the tips of the lower branches, back to a growth bud. This gentle pruning strategy will encourage branching along those stems without shortening them very much. But don’t over-trim! Pyramidal-shaped hollies should always be kept in their natural shape, with the lower branches wider than the uppers. If you prune back the lower branches too far, those branches can be over-shaded and can weaken the plant.
Thin Out Crowded Upper Branches: Next, thin out any crowded branches in the upper part of the plant, by completely removing them at the trunk or main branch. Thinning will help let light and air into the plant. This will not only help with shade problems, but also with air circulation and disease prevention. Don’t overdo thinning, though, since those branches may not grow back. When you’re finished, the plant should still look nice and full, just opened up a little.
Time Pruning Wisely: Prune hollies in late winter or early spring, during dry weather.
Dispose of Prunings: If you suspect a disease or pest problem, bag and discard all the trimmings, and rake up any fallen leaves underneath the plant, to prevent its spread.