AusBonsai

Frequently when a newcomer to bonsai posts a picture of their new stock and ask for advice on what to do the answer is "trunk chop".
Trunk chopping is an excellent way to reduce large stock to a more compact form desired for bonsai. But how many of us know the best methods and techniques to achieve a natural, tapered look?
Following is an article written by Andy Rutledge and reproduced here with his permission, that covers the basics of correct trunk chopping and the potential problems from incorrect techniques. The original article can be found on Andy's website The Bonsai Journal.

Trunk Chopping 101 For Deciduous Trees
by Andy Rutledge, U.S.A.

One operation that every bonsai artist has to perform from time to time is the trunk chop. It is seldom that you will be able to make a bonsai without making some large cuts on the trunk. This is especially true if you work with trees of any significant size.
Larger trees need to be cut back and made more compact to be of use as bonsai material. Sometimes the upper trunk is removed in favor of a smaller shoot that will serve as the new leader. In other cases, the trunk is cut back to a point where there is no potential shoot. In this case you have to wait and see where one or more buds will pop to form a new leader.
There are right ways and wrong ways to cut the trunk of a potential bonsai tree. In this article, I'll detail the best methods for chopping the trunk of most deciduous trees, like maple, bald cypress and elm.

Timing

The best time for most trunk chops is in mid to late spring or early summer (depending on your geographic location); after the new leaves have formed and begun to harden off.

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Case 1
Cutting back to an existing leader a tree suitable for a chop
Here we have a likely candidate (above). This tree already has pretty good taper, but it is too tall for bonsai purposes.
Until now, you've been growing the trunk for size and you're ready to begin its transformation into a bonsai. You've decided to cut back the trunk to an existing small branch that will be the new leader (indicated by the red arrow).
Use the saw and cut a little bit above the branch. Be careful not to damage the branch that will become the new leader.
The following images show a detail of right and wrong ways to make this cut.
Good (above)
Cut back to a bit above the new leader.
Use a cutter and then the grafting knife to reduce the wound to the shape shown here. The rounded gouge can be used to create a channel around the interior perimeter of the wound so that the callus starts by rolling into the wound. Be sure to apply cut paste to the wound.
When it has healed, the transition from the scar to the new leader (that has now grown thicker and has been cut back) is natural looking.
Bad (above)
A cut at the level of the new leader must not be left straight.
When the wound heals and the new leader grows thicker, there will be an ugly, flat transition and the new leader will bulge above the old scar. This is not natural looking.

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Case 2
Cutting back with no existing branches
A straight trunk that you want to cut back.
Here you have a straight trunked tree; perhaps an elm or a bald cypress.
On this tree, you may want to cut the trunk back to a point where no branches are growing. You will have no new leader and will have to wait for buds to form and create a new leader. You hope that a bud will form in the correct place, but you don't know what the tree will do.
In this case, since you cannot be sure where a new shoot will grow, you should not work too fast and begin your taper. Instead of cutting on an angle, cut straight across.
The following sequence of illustrations shows what can happen if you do things right of if you do things wrong.
This is a mistake! (above)
The following images will show you why.
Oops!
When the new shoots emerge, they may or may not grow where you would like them to.
No shoot emerged at the top of the tapered slant. This presents a problem...
…and here's the result. The shoots did not emerge at the top of the tapered slant, so now the trunk has died back to where the shoots did grow.
This is not likely what you had in mind and your options are now severely limited.
Instead, cut like this;
Good!
This is how you should cut the trunk in this case. This way, you are not committed to any one front or any particular branch configuration.
This allows for many possibilities.
Applying cut paste to the large wound can help in preventing dieback, which often occurs before the new buds form.
Now when the new shoots emerge, you have your pick of which to use for the new leader.
After you've chosen a leader and removed the others at its level, you can then shape your trunk to accommodate the future growth of the leader/trunk.
The shaping of the wound is done just as in the previous example. The new leader and the trunk will eventually form a natural looking transition.

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If anyone has photos that show good examples or the detail of healed trunk chops, or any knowledge to add to the above, please post it here.

Regards,
Steven

Thanks Steven,

Handy info that's not exactly obvious to the novice. This might just save some ugly scars in the future.

Very handy. thanks

Hello Steven,
Thanks for a great tutorial ,there is allways something new to learn.
Cheers John.

hi steven,
very well done and easy to follow, one thing i have learnt is with reducing large tall trees such as 10 12 feet high, you must cut slowly little at a time. i have some pics some where in collected i think of a trident that i come across, the tree was 14 foot high hiding amongst other tridents that i will soon be collecting.
i have now reduced down to around 1100mm from memory, any way the pic shows, i had chopped a couple of feet then let rest for a while then again chopped more. the reason i learnt for this is to prevent bleeding of the tree, sounds funny but trees do bleed as humans do, there is only one reality, another time for that one.
bleeding of the tree i have found is pretty much die time in some cases. a lttle can be not so drastic. these are my experiences and a little more knowlegde to the new chopper. have you experienced this on the larger trees or heard. hope this is a help to you also.

cheers

Tutorials are good should be more

Mick

Thank-you so much for an awesome tutorial. Its invaluable to noobs like myself jumping in the deep end. Much appreciated

Thanks a lot for this tuto!!

It would seem like most books skip over the step 3 "Reduce the wound".
In most descriptions or tuto i've seen its like:
1. Cut
2. Put healing paste
3. Wire side branch to redirect trunk flow
4. Tada finished!!

Thanks again!!

I have added this thread as a Howto on our Wiki so it is easy to find as well
https://www.ausbonsai.com.au/wiki/index. ... eate_taper
Thanks Steven

Ken

Thanks it was realy helpfull to me . As i saved a realy nice little tree from a bin the other day and think it will do well.

Question.
What makes the better bonsai grown as a bonsai or can trunk chops be as good ? are there people who say choping is not bonsai ?
or is it all just a matter of skill and what you have to work with ?

Great information, thankyou.

-Is there a specific reason this is directed towards deciduous trees only? Is there much difference in the process for evergreens?

fiveoffive wrote:What makes the better bonsai grown as a bonsai or can trunk chops be as good ? are there people who say choping is not bonsai ?
or is it all just a matter of skill and what you have to work with ?

Trunk chops are the quickest way to get taper. Choping is part of bonsai, although it doesn't have to be.

TheNumber13 wrote:Great information, thankyou.

-Is there a specific reason this is directed towards deciduous trees only? Is there much difference in the process for evergreens?

Just don't do the "Cutting back with no existing branches" on evergreens.

TheNumber13 wrote:Great information, thankyou.

-Is there a specific reason this is directed towards deciduous trees only? Is there much difference in the process for evergreens?

As scott mentions evergreens will die if you remove all the foliage, so you cannot cut back like you can with a deciduous tree. To achieve taper and trunk reduction you must either Graft new branches / shoots lower and then cut above them, or possibly you can cut back to some growth and then get some budding lower.
After establishing that growth you can then cut back to it, and thus creep the growth lower. This is a time consuming way to go tho,and pretty hit and miss too.

Ken

I am not trying to be difficult so please go easy on me!
I think that perhaps a distinction between say broadleaf evergreens and evergreens with needles (pines, Junipers, cedar, fir, etc) should be made.
I can think of a few evergreens that can cope with this treatment...Box, Olive, Cork Oak etc, etc...
Don't try this with Pines and the like!
My worth. And I am sure that when Ken and others wrote that info they assumed that you would understand what species they were refering to!...I only pointed it out for absolute beginners who may not be aware of the distinction.
I hope you understand where I am coming from?
Cheers, Dario

Dario wrote:I am not trying to be difficult so please go easy on me!
I think that perhaps a distinction between say broadleaf evergreens and evergreens with needles (pines, Junipers, cedar, fir, etc) should be made.
I can think of a few evergreens that can cope with this treatment...Box, Olive, Cork Oak etc, etc...
Don't try this with Pines and the like!
My worth. And I am sure that when Ken and others wrote that info they assumed that you would understand what species they were refering to!...I only pointed it out for absolute beginners who may not be aware of the distinction.
I hope you understand where I am coming from?
Cheers, Dario

Gday folks!

Well said, Dario! I was in the process of writing almost exactly this.

As well as the species Dario mentions, there are numerous Oz native broadleaf evergreens which cope well with trunk chopping below any foliage/branching, including some (many?) Eucalyptus and Ficus species.

Thanks!

Fly.