To Prune or Not to Prune

If I were to ask you, what you believed to be the single most positive and healthful procedure we can do for our woody plants, how would you respond? What part of your maintenance program is most important to your plants? Hint: when done incorrectly, this procedure can be more disastrous than any other. Is it the application of herbicide, insecticide, miticide, fertilizer or mulch? In truth, it’s a tie with site selection and pruning nose to nose in a photo finish. Let’s see how each plays a part in caring for our precious plant material. When I began this conversation the answer to the above question was pruning, but the more I thought about site selection the more I realized neither could exist without the other. We’ll take a look at both, and you make the call.

Let’s think about some ridiculous situations. Picture a European beech, a weeping willow or an American basswood as a foundation plant? What about yews, rhododendron or boxwood along the edge of a wetland that feeds into your pond? An American holly at the corner of your house? An azalea as a focal point in the middle of your sun filled front yard? Lilacs, crepe myrtle, forsythia or nandina in full shade? And, conversely, how ‘bout serviceberry, redbud, and American hornbeam in full sun? Had enough, ok, one more. White pine planted as a long term screen. All of us know that none of these situations will work, so, why do we as arborists and horticulturalists deal with these situations, daily? The maintenance costs, the time, and not to mention the aggravation that could be saved during selection and planting is remarkable. State Extension Agent, Dr. Bonnie Appleton has defined this issue quite succinctly in her paper, “Right Tree/Right Location. She reminds us our most common request of plant material is that it serve the following purpose: aesthetics>size>maintenance>environment. When the plant’s most common request is that we consider: environment>size>maintenance>aesthetics. 

Looks like two very diametrically opposed ways of viewing something. We tend to look at what our plants can do for us rather that giving them what they need in order to fulfill that role. What we want and what our plants need seem worlds apart. Putting our plant material in the correct location for that species is as important as building any structure upon a solid foundation, raising a child in a loving, healthful, fun environment or running a business for safety, quality, profit, and growth. As a babe, a minor, or young adult, plants continue to ask for help. Yes, ask for help. Kids beg for help. Plants talk to us and look to us for help and structure. When we prune young plants in a fashion that builds character for future growth, we call that structure pruning. When we suggest to children how they should live, act and grow we help them structure their lives, or at least we try. We give them guidelines to follow. Plants begin just as children, and structure is a great word to use. In fact, woody plant physiology is genetically structured in such a way that young plants must be treated differently that old one’s, especially when it comes to pruning.

The bible states, “bring up a child in the way he should and he will not depart from it”. I ask not for religious discussion, but instead, an analogy. Young plants need to be pruned when placed in an urban situation. We ask plants within this urban environment to do things they would not do in the natural forest. These things include producing lower branches or allowing them to grow with acute or envaginated crotches. A tree in a natural setting will shed any parts that are not productive or viable. Look at the trees deep in the woods, most have no lower branches and most often exist as a single or “central” stem. They become that way with time. We, however, tend to rush and be impatient with trees. We want to make them fit into our mold and then wonder what happened when they fall over, break apart of even die. For these reasons we must care for the urban tree in a way that will create comfortable living conditions for a particular species. Back to our bible verse. 

Humans and trees are most pliable when young. Scientists look at a young tree’s make up as having a “mass” that is dynamic, or always moving, and functional. All parts of the tree can work towards compartmentalizing or closing off wounds. This keeps the bad wood separate from the sound wood. Bad pruning inhibits this from occurring, good pruning encourages this remarkable process that can be seen in a tree’s vitality as it grows. Good pruning enhances a tree’s natural, genetic growth patterns, while even more dramatically, improper pruning can bring a tree to a condition of elevated risk long before it should occur naturally. The beauty of this can be seen in what we do in our yards, everyday. I believe these two practices create more value and good will to people and plants better than any other prescription could bring. Equating this to us humans would be someone who consciously eats fruits and vegetables daily along with extended periods of exercise during a day’s routine. I am afraid in both worlds, this is the exception rather than the rule.

This all started in a clients yard as we were admiring how nice a row of English boxwood looked. She mentioned, “you know, you have pruned my boxwood for 15 years”. That’s when it hit me. English boxwood grow to thick to their own good. They grow so thick that their interior gets no light and becomes leafless. This reduces the amount of leaves to a dangerous level leaving little photosynthetic surface. Any plant that cannot make enough food for itself will begin to decline. All the spraying and fertilizing in the world won’t help. On the other hand, what happens when we prune that boxwood to allow for ample light and air penetration? We spark inner growth, and create more green surface area so the plant can care for itself. I have never treated the above boxwood for mites or psyllid, and they don’t need it now. They are lush, green, and glossy because they have been pruned correctly, according to their requirements. That made me look at other properties and the results were the same in every case. Large old white oaks were magnificent because we would never remove more than deadwood, except in very special cases. These big old shade trees have their own energy to mass ratio and far be it from us to change that naturally set up relationship.

I promote these two issues of site selection and proper, artistic pruning because of the genetic requirements that dictate our plant’s response to what we do. To often, these environmentally set standards have not been followed by our industry. It is time we read between the lines and begin to listen to what these plants have to say. As professionals who are suppose to know, and as human beings who have been charged with the responsibility of stewardship we must act accordingly. We must listen and continue to learn, and as my friend Ron Rubin says, “we must do the right thing and we must do that thing right”. Put the right plant in the right place and care for it as if it were your own, forever. Happy planting!

Copyright 2005 by Peter Deahl. All rights reserved.

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