Five steps to pruning anything refers to not only trees but also bushes and other woody plants. Here are the five steps.
Step 1: Remove all dead branches. Also look and remove unrepairable, dying, damaged, and diseased branches.
Note: Trees do not have the ability to head similar to you and I. They encapsulate to cover a wound but never heal in a traditional sense. (I have written a blog about this, Tree Autopsy: How do Tree "Heal"?)
Step 2: Establish a dominate leader (or your desired structure). In this process you select where you want the plant to grow. In most trees you want one stem that originates at the trunk and grows straight up through the center of the tree out the top.
Step 3: Establish the lowest permanent branch. We want to know the lowest branch that at some point in the future will the the lowest branch. It may not be the lowest branch today but it will effect how we prune the tree today.
Step 4: Establish our scaffold branches. Scaffold branches are the permanent branches that will be the structure of the mature tree. We need to select branches that are spread at least 18" apart for larger trees and spaced evenly around the parameter of the tree.
Note: It may be helpful to mark these branches so you can be coherent in your trimming from year to year.
Step 5: Subordinate, or reduce, branches that are not the leader, lowest permanent branch, or scaffold branches. This is to guide the tree to provide more energy to the branches that we want to keep. The branches that we are subordinating will eventually be completely removed.
Triming a tree sounds easy until you start looking at a tree and realizing that you have a lot of hard decisions to make. This is understandable. Take your time. Be willing to change your mind as time goes along, as you may be forced to via wind and ice damage.
This week we worked on caring for several mature evergreen trees in a client's backyard. The tree had not been pruned when young and therefore has several structural issues. Our focus was to prune to help minimize the structural weaknesses and promote new and strong structure to make sure this family has a healthy and safe tree for many years to come.
As with all pruning we started removal of dead wood. This had a surprising affect on these evergreens. In the image below are two trees. The tree to the left is one I have not yet removed dead. The one to the right had all the dead twigs and branches removed.
If we stopped there this tree would be in a lot better shape already. There would no longer be wood rotting and inviting disease into the tree. There also would not be the dead wood attracting wood eating insects to your property. The structure of the tree is better off because some of the wind can pass through, reducing the stress on weaker limbs.
Of course we did not stop there. There are more things we can do to help this tree be healthy and productive for years to come. The next four steps of pruning were completed and this tree in now positioned to continue growing healthy and strong.
Today I had the privilege to work with Wood Saver Milling. We milled a large black walnut tree that was removed because it was threatening a neighbor's home due to structural issues most likely due to it being topped in the past and had already lost some or its large braches at thier week connection points due to topping.
Something that supprised me and may supprise you is that trees do not heal in the same you and I do. Trees are able to encapsilate wounds but the scars, dead wood and weekness is permanet. In the above three images you can see examples of this. These images show a 6"+ cut that was created in a process known as topping. This cut was made using a heading cut, one of the most damaging to trees. You can also see the new growth encapsalated over the stub over a period of years. It can grow around all sides yet as you can see the material is permanetaly dead and forms a permanet structural weekness. Also, in the year it takes to heal a large wound it opens the tree up to bugs and decay. The new outside growth surounding the old cut piece is all that is supporting any tree growth above. If you were to clip the wood on the edge of the board, parallel and in line with the old cut, the remaining wood would just fall apart. Let us look at other less catastrophic pruning and the trees response to the damage.
In the the images directly above you can see an example a a proper pruning cut and how the tree was able to encapsilate the damage with minimal damage to the structure and tree health. The cut appears to have been made at the bark ridge and branch collar making it as easy as possible for the tree to encapsilate.
Trees not only stuggle from damage caused by humans through pruning and topping but from the lack of proper pruning. The images directly above are from a steep branch angle causing the tree to include the bark in its center. The tree is basically growing into itself and what is in between the two branches, or the branch and base, is encapsilated, leaving a permentant weakness in the wood. This would be the equivalent of a perforated edge in paper, substantialy weaker and more likely to rip. The steep branch angle and included bark shown was over two feet deep!