Tree Pruning Basics

Pruning deciduous (leafy) trees is a great way to make your shade tree or ornamental flowering trees stronger and more beautiful.  By removing weakly attached branches, and excess branches, we allow the more strongly attached branches to get even stronger as they benefit from more space and light.

The weakest branches are almost always those growing at the steepest angles, trending closer to vertical.  Branches attached to the main trunk at lower angles, trending more towards a 45 degree angle and even lower angles all the way to horizontal, will form far stronger attachments to the main trunk, and seldom split off from the trunk during storms.  The branches attached at steep angles usually are weakly attached and are usually those that suffer storm damage.

A great many trees have too many branches.  See photo #1.

Photo #1

There are at least 5 branches coming out of the trunk in a very small area.  Pruning out the steepest angled branch that the hand saw is pointing at is a good start.  Removing one or two more after determining which will look nicest and most balanced when left in place is probably advisable.  In the long run, two or three branches in this area will be plenty, and more storm resistant.  Where branches cross and rub on each other, remove part or all of one of the rubbing branches.

To make pruning easier, prune your new trees every two years the first ten years after they have been planted.  When they get too large to work on yourself, call a reputable tree service to do the job.  Always be very careful if you use a ladder, making sure it is stable and not wobbly.  After the first ten years, a professional pruning every four to five years should be adequate.

Good tools for tree pruning include bypass hand pruners,  loppers, hand saws, pole saws and pole pruners.  Occasionally power pole pruners and chain saws can be used, but this requires extreme caution, and is usually best left to the professional tree trimmers.  If you prune early and often in the life of your trees, hand tools are usually up to the task, since the branches being removed are small.

I use the rule of thumb when pruning young trees.  If a branch will not be one of the permanent branches, remove it before it gets any larger than your thumb in thickness.  This means wounds will be smaller, and new tissue will grow over the pruning cuts faster, reducing the chance decay will enter the trunk.  If your pruning is done in a timely fashion, most branches you remove will be ¼ inch to 1 ½” in diameter and the wounds will “heal” in two or three years.  Its sure a lot easier than branches that have been left on too long and you find yourself removing branches 4” to 12” in diameter.  These larger wounds would take five to fifteen years to have new wood/bark grow over he wound.  When I am really proactive and ahead of the game, I’m typically pruning off temporary branches when they are ¼” to ¾” in diameter.  This gives the very best results.

Try to avoid removing more than 20% to 25% of the branches/leaf mass of the tree in any one year.  This will have enough leaf mass for the tree to be healthy and vigorous, and produce enough stored starch and sugar for the next year’s growth.

When you remove a branch, do not cut flush with the trunk.  Look closely and determine where the branch collar is located in the area where the branch is attached to the trunk.  This is an area where the branch is a little wider at its base.  The tissue of the branch collar tissue naturally produces rot resisting compounds called phenols.  When you remove the branch AND leave the branch collar in place, the phenols work over the wound and prevent decay.  If your pruning cut is flush with the trunk, you probably removed the branch collar, and few phenols will be present to prevent rot entry.  Leaving the branch collar in place will result in a modest bump on the trunk.

When you make a pruning cut that leaves the branch collar intact, it will be as if you left a bump on the tree trunk.  AVOID leaving a stub of the branch sticking out of the branch collar as seen on photo #2.

Photo #2

If a stub is left in place, this will also take much longer to form callus tissue (new bark and wood) over the wound.

Photo #3

Photo #3

shows the resulting side view after making an additional cut to remove the stub.  This leaves a modest bump where the branch collar is intact, and will be able to help retard the entry of rot.

Photo #4

Photo #4

shows a head on view of the intact branch collar with a ruler showing that the wound diameter is 1 ¼”.  After taking the #4 photo, I made a flush cut for demonstration purposes.  This cut removed the branch color (the bump) and resulted in the much larger 2” diameter wound seen in Photo #5.

Photo #5

This larger wound will take five to six years to achieve full coverage vs. two to three years for the 1 ¼” diameter wound.

Photo #6

Photo #6

shows a fairly steep angled ½” branch about to be removed with a hand operated bypass pruner leaving an angled bump and leaving the small branch bark ridge intact between the steep branch and the tree trunk.  The branch bark ridge is commonly seen on steep branches instead of the classic branch collar shown in Photos 1-5.  Do NOT remove the branch bark ridge.

Photo #7

Photo #7

shows the branch bark ridge angling downward from the top of the slightly angled pruning cut.  It is ok to leave an angled bump of this sort in place when pruning off a steeply angled branch.  Do not make a flush cut straight down or you will have a far larger wound.

In summary, prune your trees early and often the first ten years, removing branches before they get larger than your thumb.  Remember that less is more.  Really strong and beautiful trees quite often have between three and six or eight main permanent structural branches when they become mature trees and this is the result of gradual pruning over a period of several decades.

I’ve also noticed over the years that the most beautiful shade trees have their first (lowest) main branches at a height of ten to fifteen feet about ground level.  This keeps them out of the way of mowers and vehicles, and allows enough light to reach the ground to keep grass thick, healthy and attractive.  Shade is the enemy of turf grass.  Gradually prune your trees to a high canopy and the grass underneath should look great!

Be brave,  go forth and prune early and often.

One thought on “Tree Pruning Basics”

  1. Thank you for this great pruning instructional. The pictures
    are very helpful.
    Maybe you should see if the newspaper would publish this
    as well.

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