There is a right way and a very, very wrong way to prune your tree

Recently I had to clean up the debris from a large branch that had fallen out of a Royal Poinciana. From afar it seemed to be a very healthy tree; it had a nice straight trunk and a symmetrical canopy. However, a closer look revealed structural problems. It was at least 20 years old and had never been properly pruned. That meant branches were growing in all directions, including inward, and it had “bunches” of smaller branches growing from the same points.

Royal Poinciana is notorious for this kind of growth, especially when branches have been broken off in a storm or pruned improperly. Many new branches will grow out below an old limb cut or break. Poor connections develop between these new branches and the old ones.

This tree definitely went through several hurricanes that caused some damage. The unchecked new growth was similar to what happens when a tree’s branches are cut down to stubs. This is commonly known as “topping” or “hat-racking.”

Topping may be one of the worst pruning practices that can be inflicted upon a tree. However, many of us in the past, myself included, cut trees in this manner as it was the accepted wisdom. We have since learned through experience and a lot of scientific evidence that this method is simply not acceptable. Now it is also illegal in many municipalities, including the City of Miami.

The most common rationale for topping is to reduce the size of a tree. Homeowners often feel their trees have become too large, and they fear they’ll pose a hazard, particularly during a hurricane. Topping, however, does not reduce the hazard. In fact, topping will not only make a tree more hazardous in the long term, it will cause very rapid new growth, quickly returning the tree to its previous overgrown state.

Topping removes 50 to 100 percent of a tree’s foliage. Because a tree’s leaves manufacture the food it needs to live, removing them can often lead to unforeseen problems, such as insect or mite infestations. The severity of the pruning also triggers a sort of survival mechanism. Since the tree needs to put out a new crop of leaves as fast as possible, dormant buds on the branches burst to life, growing in multiple shoots below each cut.

The survival mechanism that causes a tree to produce multiple shoots comes at great expense. Unlike normal branches that develop within a socket of overlapping wood tissues, these new shoots are anchored only on the outermost layers of the branches that have been cut. They grow quickly -- too quickly.

Unfortunately, these shoots are prone to breaking when the foliage gets too heavy, and especially during windy conditions. The irony is that while the goal was to reduce the tree’s height to make it safer, it has been made more dangerous because of the poor connections between the new branches and the old wood. Topping creates hazards!

The preferred location to make a pruning cut is just beyond the branch “collar” (swollen area), at the point of branch attachment. The tree is biologically equipped to close this wound, provided the tree is healthy enough and the wound is not too large. The exposed, recently cut wood tissue will begin to decay. Normally a tree will “wall off,” or compartmentalize, this decaying area. But few trees can defend the multiple severe wounds caused by topping.

An acquaintance approached me recently because he heard I was an arborist. He asked me why the large tree in his front yard that needed some maintenance had received two bids with almost a $2000 disparity between them. Why were the bids so different?

I asked him if the tree was valuable to him. Would he get the same price if he sold his house and property with or without the tree? He said that one of the reasons he bought the house was because of the tree. I then asked him if the two bids had come from certified arborists. Apparently only the high bid was from a certified arborist.

I explained that the tree was an investment, and that if he wanted it to be as healthy as possible for as long as possible, he would need to get the proper care for it. A bona fide arborist needs continuing education credits to maintain his or her arborist certification. Obviously some arborists are better than others, depending on their education, experience, and talent. But all certified arborists will provide better and more knowledgeable service than tree-trimmers who have no rigorous training. Be sure to check credentials before you contract for work.

Periodic pruning isn’t done just to make a tree look good. It should also attempt to reduce the risk of structural failure.

Jeff Shimonski is an ISA-certified municipal arborist, director of horticulture at Jungle Island, and principal of Tropical Designs of Florida. Contact him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

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