There is not a lot of information on the net about this process. I started treating my maples this way about ten years ago. Walter Pall has spoken about it at his blog, but not much in the way of how to keep up on the process.
There are other ways to treat the canopy of a maple tree and these other treatments have to do with where the tree is in development. During the trees early life, much like candle management on a pine, early treatment is more coarse and in a branch building mode. There is no need for select bud pinching on a tree that will have it’s branches cut many times during the growing season. Bud selection in April likewise on a pine is kinda pointless.
As trees in training begin pushing new buds, the main branches are chosen. As they harden off, the permanent primary branches are now allowed to elongate to gain thickness. Wire is applied and the tree is left to grow. In mid summer these can be cut back when the tree slows down and then allowed to once again elongate in late summer into fall. In Fall all the branches are pruned back hard and then new directions can be worked into the primary stubs. After successive years and primaries set, the same can be done to build secondaries. During the building of secondaries the first beginnings of hedging can now be allowed to begin.
First I will explain what hedging is to me. It may not be the same for all but for the sake of my blog I will call it hedging and this will be the technique I have developed and use. I feel I get good results and tweak the process as the years go by.
The primaries are set to a specific form. It is this form that the tree is hedged to. This form will now be the template for pruning/ hedging for the next several years. The form may grow in volume and become larger, but the shape must remain the same. To change the shape after several years will mean to cut off all the work the years of hedging have provided.
I will provide a few photos of a tree thru the process and up to where it is today. This is the tree as purchased. It is bare rooted and all the branches that will not be used are removed from the trunk.
At the end of the first season the tree is kept compact by hedging to a conical shape. This shape keeps the bottom branch longer and thicker while pruning back the branches at the top smaller and shorter.
In fall the primaries are chosen and wired.
The front was reestablished with a quarter turn.
This Spring, after bud break the tree is allowed to run for a few weeks. As the shoots begin to harden off, the tree is hedged for shape. The hedging is done with regular pruning shears but the shape is taken back to a preconceived place much like pruning a hedge, hence the term hedging.
A couple of days ago the second flush of leaves have hardened off and the hedging process can continue all summer long about every three to four weeks. This does not weaken the tree, on the contrary, many buds will form from the cut back.
In this shot we can see that the bottom branches have not been trimmed to allow for enlarging the branch and gain some extension.
This is another tree that has received the same process. Again the tree as purchased and this one was radically cut back.
The tree received several approach grafts to improve branching.
This is the primary branch selection process and these are allowed to grow and cut back.
As the tree progresses the canopy is hedged for shape. Again this is achieved by hedging to a conical shape.
Back of tree.
Hedging is done each time after the hardening off of the previous hedging. This keeps a continual flow of new twigs coming while other are budding, some are growing.
At this point after the yearly hedging process the branching is now at the secondary point and a more feeling of ramification can start on the frame.
Bud break this year. The tree is starting to really push now and a cut back is only weeks away.
The most recent hedging is now starting to show how the layers are being defined and the canopy is shaping up to be a slanting trident. Not seen often.
So what happens after years of trimming and hedging?
Each fall the tree will be pruned after leaf fall. This is the time we can come in and remove heavy growth at branch ends, and thin the structure out if needed. It will be needed. After several years the tree should begin to settle down into a nice shape and the final tertiary ramification can begin. It takes many years to build a fine canopy of fine twigs.
This tree has been developed by this method for 14 years. the outline of this canopy only needs periodic light scissor pruning of shoots to maintain the outline.
In the Fall the top may look like this. very coarse and heavy growth due to apical dominance.
Pruning can lighten this feeling and help establish a framework for the tertiary buds to follow.
Last years hedging can bes een in blue. The current years hedging will take place between the blue and red zone. This is where I want the small twigs to ramify.
Hopefully at the end of the season I will be rewarded with a small crop of twigs to build on.