Too often, large shrubs are removed in their prime because they become overgrown and unsightly. If understood, there is likely a lot of life left in these plants but over time they can simply become overgrown. During most plant’s lives, they just have to be told (with pruners) how you want it them to grow. Thinning them out from time to time increases air flow and allows light into the interior branches, which stimulates them to grow even fuller.
Start with identifying and removing all dead or broken branches back to live growth or the ground if the entire stem is dead. Next, look for any branches that are interfering with the other branch growth such as those that are rubbing and crossing one another. It is better to remove the branches that are growing inward as they are likely to cause trouble down the road. As you begin to prune, the shrub may start to look sparse and you may even notice that you start to lose cover and privacy that the dead and unwanted branches were obscuring. Don’t panic. Plants take patience. They live their lives at a different pace than ours. Through the pruning process you will have freed up it’s resources by removing extraneous branches and the following spring your shrub will sprout vigorous and new growth like never before. You can even stimulate more lateral growth by removing about a foot or so from the ends of the branches. Just make sure to prune back to a bud or branch that is facing outward.
When deciding how much to prune, remember the three R’s. Remove a third, Reduce a third and Retain a third. This can change depending on what you are trying to achieve. In the video below, I repurpose a large viburnum and limb up every twig and branch to eye level to create a small multi-stemmed tree. If you have a severely overgrown shrub with few good healthy branches left, then revitalization pruning might be in order. That is where you essentially start over and cut the entire shrub close to the ground, making sure to leave some buds on the base for new stems to grow back from.
The timing of pruning depends on the shrub in question and what you are trying to accomplish. Flowering shrubs will either bloom on the previous years growth or on new growth, and some will bloom on both. So if you prune in fall you may be pruning off your flowers for next year if you are reducing the height. Therefore, it is best to prune those plants right after they finish flowering and start pushing new growth. If you are just pruning out deadwood and broken branches, that can be done at any time. If you are removing a considerable amount from the shrub, then it is better to do so when the shrub is dormant in March to avoid any shock to the plant. If you are just doing some light shaping, either spring or fall is fine. The bottom line, don’t be afraid, your plants will thank you!