The American holly was 10 feet tall; I pruned all of its side branches to within four to six inches of the main stem. The Japanese hollies were pruned back to within two to three feet of the ground. The side branches of the Burford holly were pruned back to inches from the main stem.
I have done this same type of pruning to hollies for years here at Upakrik Farm, but no one seems to trust me. Even my wife claims that plants shudder in their roots when they see me coming with pruning tools in hand.
How do the hollies survive?
Buds are one factor. Hollies have thousands of latent buds waiting for an opportunity to grow. They also have the ability to develop adventitious buds at every cut surface. Adventitious buds are spontaneous buds that appear under proper conditions.
Root systems are another. Mature hollies have large root systems with lots of reserved energy waiting for spring. The root system is charged and ready to grow at the top as soon as the weather warms.
Combine a large-capacity root system with no top growth to feed, a large mass of latent buds and the formation of adventitious buds, and impressive new growth results.
Prune with this caution: Do not fertilize or water excessively until after the tree has exhausted its reserves. There is generally sufficient reserve in such a root system for at least one year of growth.
During the first year of growth thereafter, you must prune frequently to develop compact growth. Those latent buds that are first to develop will tend to maximize growth. By pruning these early growing shoots, you encourage those slower developing latent buds to emerge. Pruning those early developing shoots at two- to three-week intervals will result in more uniform, dense growth.
Don’t be afraid to prune your hollies severely. They are survivors. But do it now, before spring growth begins.