On Summertime Pruning

One of the most frequent questions I?m asked is when to prune. Though the answer varies with particular species and needs, I believe that for the most part, pruning on woody perennials is best spread throughout the year. Rather than going in one time (usually winter), if the same amount of wood (foliage) is removed, it is often better if this is spread out over the course of several lighter prunings. There are a couple of reasons for this.
 
One is that the act of pruning is the act of creating injuries, injuries cause stress, and stress is better handled by living beings if given in several small doses, rather than one large one.
 
The other reason is that by pruning lightly several times a year, we can be both more immediately reactive to the way the tree or shrub is growing, and more proactive in leading and coaxing growth into forms we desire more and that are better for the plant.
 
Lets imagine a Desert Willow for example, well established and growing well. A good rule of thumb for pruning woody perennials, especially trees, is not to remove more than 25% of the foliage in a year. Normal procedure would be to remove all of that in one pruning in the winter. However, say that winter pruning was reduced to just 10%. Later, in the spring, after new growth has pushed forth, the same tree is revisited. One can then observe how the plant is responding to the winter pruning. Selective pruning of new water sprouts and suckers should occur, removing them entirely, or heading them back to a bud, to slow them down. The other responses of the tree can be studied, and the new growth that is not ?behaving? well can be slowed down or removed. In this pruning, only a small percentage of foliage is removed, around 5 to 10%. The tree then responds to the work of the arborist, and energy is allocated based in part on the pruning just done, and growth corresponds. Following this, in summer or early fall, the tree is visited again, and the pruner then responds to the trees late spring growth, and influences and redirects growth again. Another 5 to 10% is removed, and the total for the year not exceeding the approximate of 25%. The tree responds in its fall growth to the pruning of the summer.
 
This approach is much more interactive with the trees growth, and better results can be achieved.
 
A note of caution is in order though. I think that desert-adapted species are better candidates for summer pruning than are more moderate to high water users. The higher water users are often much more susceptible to sunburn of foliage and trunk, and when tissues that were previously shaded by other foliage are exposed to brutal summer sunlight conditions, damage can ensue. Minimize or eliminate pruning of such plants to cooler times, and be sure not to remove large enough chunks of shading foliage, so as not to open new tissues to extensively more sunlight.
 
Remember also, that if you do just one heavy pruning a year on trees and other woody perennials, that pruning is usually best done during the dormant season, winter.
 
One final thought on summertime pruning. Dead wood can be removed at any time. Whether it be spent flower stalks, dead twigs or dead branches, removing them never hurts the plant, and will actually allow the wound to close more quickly. Just cut all the dead off, back to, but not into, live tissue. It is usually visibly obvious where the line between dead and live tissue is.
 
So, in the summertime, if you?re just aching for some pruning to do, go for it, just go light. And if there?s just one or two minor branches that are bugging you, or whacking you in the forehead, or obscuring a view, whip out the hand pruners and saw, and have at it!