Mid- to late winter is an optimal time to prune most trees. Insects and diseases that attack tree-wound sites are not as active, and the time for the most rapid wound closure is about to begin in spring.
While this general truth applies in most situations, keep in mind that depending on where you live across the state and what tree species you are pruning, there are exceptions. For example, if you live in an area with active oak-wilt issues, it is best to prune in January, although promptly-applied wound coatings can allow pruning outside of this time. Also, a case could be made to wait for spring-blooming trees to complete their bloom show for aesthetic reasons before pruning them.
Pruning may be the least understood and most incorrectly performed of all our gardening chores. It also can cause the most significant aesthetic and economic damage of any task in our gardens and landscapes.
Let’s consider several foundational pruning principles that could help avoid some of the common mistakes I see people make. When these are understood, we are much better able to use pruning to enhance a tree’s health and structural integrity, which will provide years of enjoyment and increased value to our property.
BEFORE CUTTING
Let’s begin with the question, “Why do I think this tree needs pruning?” If your answer is based on an understanding of the way that species grows and a tree’s response to various types of pruning cuts, you may be on your way to a quality pruning job, or perhaps the decision not to prune.
“Should I contact a certified arborist?” is an important initial question, especially if your tree is medium-to-large and/or has structural issues. These folks are trained in all the principles and practices of tree care based on arboricultural science. At http://treesaregood.org/findanarborist you can search for arborists within 10, 25 or more miles from where you live.
Some areas may not have an arborist nearby or have too few to keep up with requests for help. If so, they may be able to suggest someone else who they feel does good work. Just choose carefully, as the work done on your tree can end in long-term health and strong structure or else malpractice that can weaken or disfigure the tree for the rest of its life.
A couple of other tips are: ask for references and check to see if they did good work, cleaned up before they left and showed proof of insurance. I hate to have to add this, but these days it wouldn’t hurt to call and confirm that the insurance is current. Enough said about that.
I’m not saying that only a certified arborist knows how to prune a tree, but from my decades of observation and experience, far too many self-approved tree trimmers lack the training needed to do it right.
If you choose to do the work yourself, ask, “How and where should I make the pruning cuts?” Then ask, “What will the tree’s growth response be to these cuts?” If you can provide an accurate answer to those two questions, you’re ahead of many self-declared tree-care experts.
BEGINNING TO PRUNE
You may be wondering, when in the life of the tree should pruning begin? I’m glad you asked. At planting. Training a tree begins at planting and continues for at least the first five years after planting. These early years are very important because if done correctly, there will be much, much less pruning to do in the many years thereafter.
When you see that a branch is not in a good place, or at a proper angle, or not a permanent branch, it is much better to remove it sooner rather than later. A branch the size of your thumb leaves a wound about the size of a quarter that will quickly close over with a callous. If you wait a couple of years, that cut might create a wound the size of a soft-drink can, which may take two or more years to close. Plus, all the wood and foliage that the tree grew that you have now taken off could have been directed into growth that will build the long-term structure of the tree.
The longer it takes a cut to close over, the longer the interior wood of the tree is exposed to moisture and decay organisms. As decay progresses, the structural strength of the trunk or major branch that is affected becomes weaker and more likely to fail in a windstorm.
I will perhaps overstate something to make a point for anyone who has cared for a tree for many years. When you grab a saw, especially a chain saw, to remove a large limb, it is an admission of guilt. The point is: that branch which is way too low to walk and mow under, or is forming a weak narrow angle, or is competing with the main trunk for dominance, or is crowding another branch might have been foreseen and removed before it grew too large to use loppers or a small-cut pruning saw.
It’s not an arboricultural crime to use a small handsaw on branches that need to be removed. Most major sawing done by tree-care professionals occurs because they are correcting problems on trees that were not trained properly in years past. With each passing year, branch removal requires more severe cuts that often create problems down the line.
TOOLS OF THE TRADE
The basic tools of pruning are hand pruners, loppers and saws. Hand pruners are good for very small branches, about one-half inch or smaller. Choose quality pruners not cheap ones. Cheap ones are destined for the trash can. Quality pruners last for years and their blades can be easily replaced if needed. Some have ergonomic designs for less hand strain.
I’ll put it this way. You can’t afford to buy cheap hand pruners. Over time, they are more expensive, more frustrating and more likely to create hand fatigue or injury.
Loppers are for larger branches, up to about an inch and a half, although there are special types that can remove larger branches. Don’t skimp on this purchase either. A quality set of loppers, well cared for, will last for years with the benefits mentioned for hand pruners.
Saws for cutting branches are curved and designed to cut only on the pull stroke. This way they grab the limb and en-sure a better, faster cut. There are folding and non-folding types with a range of blade lengths. Again, choose quality.
Pole saws with or without lopper attachments are another tool to consider. Using a pole saw can be exhausting. But compared to the risk of standing on a tall ladder, it is a good choice. Keep all your tools sharp to make clean cuts that heal faster and reduce strain on your muscles and joints.
Wound sealers are not recommended unless you are pruning oak trees in an area where oak wilt is present. Then they are necessary. Researchers showed years ago that wound sealants are not helpful to the tree’s effort to callous and close over the wound, and in fact are often detrimental for large cuts by promoting decay of the interior wood.
TARGETING PRUNING CUTS
Many tree species form a collar — a slightly raised area near where a branch that is significantly smaller than the trunk joins the trunk. This area has a better ability to form a callous and close a wound quickly than does regular trunk tissues. Branches should be removed right where this area begins. If you leave more of the branch, the stub you leave will die and then the dead stub will prevent wound closure.
If you cut closer to the trunk, the size of the wound becomes significantly larger. Add the fact that you removed the best tissues for healing, so what follows is a long slow process of closing over the cut surface.
Some tree species may not form much if any collar. In such cases, the cut can be made closer to the trunk as long as the wound size is not much larger. One way to know where to cut in the branch-collar-trunk area is to notice where the branch diameter begins to quickly flare out as it nears the trunk and then make the cut right where the flare begins.
Cuts made elsewhere on the tree’s branches should be near where the branch to be removed joins another branch. This directs the growth into the branch that remains and is known as a “thinning cut.”
When you cut off a branch without such a side branch, it resembles the blunt end of a broom handle and is known as a “heading cut.” Regrowth will occur near the end of the branch as several shoots are produced. If you need a visual, look at most crapemyrtle-pruning hack jobs and all the thin shoots that result. This is unsightly, and when done on a larger landscape tree will result in poorly attached shoots that are prone to breakage at the point of attachment.
This pruning malpractice was especially popular in the past on large Arizona ash trees and unfortunately continues with many other species. The guy knocking on the door will say they need to do that to reduce the canopy, so you don’t have big limbs falling in a storm. Just say no.
LARGE LIMBS
When cutting off a limb, as you saw downward, you reach a point where the weight of the limb is greater than the remaining tissues can support. As the limb falls, it tears off a long strip of trunk-bark tissues.
This type of wound is very slow to callous over and in older trees may never completely close. This serious mistake can be avoided.
We use something called the three-cut method to remove a limb too large to easily hold with one hand. The first cut is made a little farther out from where you want the final pruning cut to be. Cut upward from the bottom of the branch only about one-third of the way through the branch.
The second cut is made a little farther away from the trunk, cutting downward from the top of the branch, causing it to fall. The first cut you made will prevent bark-stripping as the branch falls.
The third cut is then made to remove the remaining branch base, cutting where you want the final cut to be, just out-side the natural branch collar.
LEARN MORE
This has been an overview of some basic principles of tree pruning by focusing on avoiding some of the more common mistakes I’ve seen people make over the years. There is much, much more to say about how to train and prune a tree.
Your trees are valuable assets to your home. You owe it to yourself to take time to learn as much as possible before choosing a species, planting the tree and then training or making any pruning cuts. It is difficult to give a one-size-fits-all pruning guide because each species may have different growth-habit tendencies and require a somewhat different approach.
There are many good books to guide you in tree-maintenance pruning. I’ve found that the limbs on my tree never look quite like the illustrations in the books. Nevertheless, learning the principles and having an educated goal in mind go a long way.
There are also some helpful websites created by people who know the standard arboriculture practices to follow. Here are a few helpful links to educate and guide you.
Pruning Your Tree (Texas A&M Forest Service)
http://texastreeplanting.tamu.edu/PruneYoungTree.html
Pruning Trees from the International Society of Arboriculture
https://www.treesaregood.org/treeowner/pruningyourtrees
Basic Principles of Pruning Woody Plants (Univ. of Georgia Extension)
https://extension.uga.edu/publications/detail.html?number=b949
Pruning Shade Trees in Landscapes (Univ. of Florida)
http://hort.ifas.ufl.edu/woody/pruning.shtml
Before heading outside to prune your plants this winter, take some time to sharpen your pruning knowledge to ensure your trees remain strong and beautiful for years to come.
By Robert ”Skip” Richter
Brazos County Horticulturist
Texas A&M AgriLife Extension Service