Trunk Chopping

[Prozart]

I got into bonsai a couple months ago, and since there's not a lot to do this time of year I've just been reading everything I can on various websites (this one included) and Reddit. I purchased an acer palmatum a little over a month ago from a nursery and am planning to chop the trunk to develop taper, but I've read some contradictory information and wanted to get some clarification here if I could.

According to this article on bonsai4me (http://bonsai4me.com/AdvTech/ATdevelopingtrunksforbonsai.htm) once you chop the trunk the lower portion stops thickening until the new leader becomes as thick as the old trunk, so you don't want to perform the first chop until the bottom portion is as thick as you want it to be.

According to this article on EverGreenGardenWorks (https://www.evergreengardenworks.com/trunks.htm) says chopping will only slow down the growth of the bottom part, so you want to perform the first chop when the bottom part is half to two thirds the desired end thickness.

In my current situation, the bottom portion is a little over an inch and the flare is a little over an inch and a half. I probably want the end thickness to be around 2 inches with the flare being 3 inches or so. So, according to Evergreen, I should do the chop now but according to Bonsai4Me I should wait until I get the trunk where I want it. I'm surprised there is this contradictory information out there, it seems like it would be a pretty easy thing to test given a few years: measure the caliper, chop, then measure the caliper a couple years later.

Anyway, any information or help is greatly appreciated. I attached an image if anyone is interested. I'm not planning on doing a chop this year (as in Spring 2021) anyway as I want to plant it in the ground and let it grow for a year, but just wanted some feedback.

 

[leatherback]

The trunk will thicken a little every year. That is just how trees functions. The more foliage is above a certain part of the trunk, the more it will thicken.

I tried to write down my thoughts on this a while ago, but I am afraid I was not very clear. It is not a very popular article..

Why bonsai loose taper - Growing Bonsai

Understanding how growth affects taper in bonsai is important. Especially in early stages when growing out your seedlings to become bassive trunks for bonsai, this is important.

www.growingbonsai.net

 

[Prozart]

The trunk will thicken a little every year. That is just how trees functions. The more foliage is above a certain part of the trunk, the more it will thicken.

I tried to write down my thoughts on this a while ago, but I am afraid I was not very clear. It is not a very popular article..

Why bonsai loose taper - Growing Bonsai

Understanding how growth affects taper in bonsai is important. Especially in early stages when growing out your seedlings to become bassive trunks for bonsai, this is important.

www.growingbonsai.net

Thanks for sharing Leatherback! I found the article, and the one linked therein about why trunks grow, very interesting reading. Based on that information I think I'll do a chop early spring 2022, after the tree has had time to recover from the root work and planting in the ground I plan to do this upcoming spring.

 

[sorce]

Welcome to Crazy!

Those 2 things are teaching basically the same thing.

Maybe Brent leaves a sacrifice branch at the first chop site which adds the last 1/3 and Harry doesn't.
Could be the trees, or the climate.

As long as you're not expecting to have taper where you can't create any, you are good to go.

Sorce

 

[Zach Smith]

You will have a challenge getting thickness in that grow box regardless of when you chop. You can get there, but it's going to take several years. If you decide to plant your tree out in the ground, it'll take two or three years before it gets comfortable there and starts to quickly put on heft - just the way it is. But that will be the way to get quicker thicker.

As a beginner, and you're going to hear this from others, you need to focus on getting as many trees are you can just barely uncomfortably care for. With all your attention on this tree, it's not going to appreciate all the love you want to give it. We can only do so much with any given tree at any given time, and waiting is not fun.

Good luck!

 

[cheap_walmart_art]

I'm surprised there is this contradictory information out there, it seems like it would be a pretty easy thing to test given a few years: measure the caliper, chop, then measure the caliper a couple years later.

Your entire internet experience with Bonsai will be more enjoyable if you stop being surprised by contradictory information.

 

[Prozart]

You will have a challenge getting thickness in that grow box regardless of when you chop. You can get there, but it's going to take several years. If you decide to plant your tree out in the ground, it'll take two or three years before it gets comfortable there and starts to quickly put on heft - just the way it is. But that will be the way to get quicker thicker.

As a beginner, and you're going to hear this from others, you need to focus on getting as many trees are you can just barely uncomfortably care for. With all your attention on this tree, it's not going to appreciate all the love you want to give it. We can only do so much with any given tree at any given time, and waiting is not fun.

Good luck!

Hey Zach, thanks for the tips! I am planning on planting this in the ground this spring and then doing the chop the next year. But I guess I'll get it in the ground and just watch it over the next year to see how it progresses before deciding whether or not to chop. And yeah I probably have about 7-8 trees in the growing out phase at the moment. I'm definitely down to get some more, although I'm thinking of picking up some trees further along in their development so I'm not just growing out a bunch of trunks. Plus I don't have room in the ground to plant very much so most of them (this maple excluded) will be put into colanders this spring.

Your entire internet experience with Bonsai will be more enjoyable if you stop being surprised by contradictory information.

Haha, oh I fully expect contradictions (especially when dealing with soil), I just expected that experienced practitioners would agree on something so easily tested - ie the trunk either stops growing bigger after a chop or it doesn't, lol.


As a random side question while I'm here, I've read that when growing out the trunk you should pretty much just let the growth go crazy all growing season and then cut it back in the fall. I did not do any kind of pruning with the maple this fall. Am I ok to trim the long shoots back now or should I just wait until fall 2021?

Thanks everyone for your input!

 

[Gabler]

A healthy tree can be pruned whenever. If your tree hasn't been repotted recently, and it has a lot of new growth from last season, it shouldn't bother the tree at all to trim it back to shape. Just don't go overboard.

 

[misfit11]

You will have a challenge getting thickness in that grow box regardless of when you chop. You can get there, but it's going to take several years. If you decide to plant your tree out in the ground, it'll take two or three years before it gets comfortable there and starts to quickly put on heft - just the way it is. But that will be the way to get quicker thicker.

As a beginner, and you're going to hear this from others, you need to focus on getting as many trees are you can just barely uncomfortably care for. With all your attention on this tree, it's not going to appreciate all the love you want to give it. We can only do so much with any given tree at any given time, and waiting is not fun.

Good luck!

I just wanted to add a caveat to Zach's post. He's very experienced in bonsai and most definitely has the trees to prove it. That being said, as he is absolutely right that ground growing is light years faster than anything in a pot, one needs to keep an eye on the nebari as the trunk thickens. Because as the trunk thickens, so do the roots. You can add inches to your trunk girth in a few years in the ground depending on the species. Unfortunately, the opportunity cost of this is roots that soon grow beyond appropriate proportions. I most definitely grow things in the ground because it is so much faster to achieve a trunk size that's desired. It is necessary however to dig it up every two, three, four years and do root work to keep that nebari from getting away from you. Many people grow things in the ground on tiles to keep roots growing laterally and prevent them from diving straight down. Hope that helps!

Cory

 

[Zach Smith]

Hey Zach, thanks for the tips! I am planning on planting this in the ground this spring and then doing the chop the next year. But I guess I'll get it in the ground and just watch it over the next year to see how it progresses before deciding whether or not to chop. And yeah I probably have about 7-8 trees in the growing out phase at the moment. I'm definitely down to get some more, although I'm thinking of picking up some trees further along in their development so I'm not just growing out a bunch of trunks. Plus I don't have room in the ground to plant very much so most of them (this maple excluded) will be put into colanders this spring.



Haha, oh I fully expect contradictions (especially when dealing with soil), I just expected that experienced practitioners would agree on something so easily tested - ie the trunk either stops growing bigger after a chop or it doesn't, lol.


As a random side question while I'm here, I've read that when growing out the trunk you should pretty much just let the growth go crazy all growing season and then cut it back in the fall. I did not do any kind of pruning with the maple this fall. Am I ok to trim the long shoots back now or should I just wait until fall 2021?

Thanks everyone for your input!

It depends on the tree and where you are in its development and how satisfied you are. Some I let grow wild all year, others I see doing something I either like or don't like and will chop during the growing season to direct things the way I want. Recently I went through and did a fall chop on quite a number of zelkovas, elms, oaks, sweetgums, etc. Earlier in the season I chopped some live oaks (those I would not do at this time of year, as their growth cycle is somewhat different than other oaks).

 

[Adair M]

to the OP:

There is a lot of conflicting information about bonsai. Sometimes it’s a case of some info being correct, and some is just plain wrong. Sometimes there are different methods, each having equal merit. For a beginner, it’s difficult to know which is which, and what is what. There are many well meaning people who practice bonsai poorly, but don’t know it.

My best advice is to find someone who’s trees you like and learn to do what they do. Don’t take advice from those whose trees you cannot see. (Pictures are ok). That’s the only way you can judge on whether they actually know what they’re talking about.

 

[leatherback]

There are many well meaning people who practice bonsai poorly, but don’t know it.

I like how you put this!

find someone who’s trees you like and learn to do what they do.

100%

 

[Brian Van Fleet]

My best advice is to find someone who’s trees you like and learn to do what they do.

Hey! That’s my best advice!
Usually followed by a comment about the club members most willing to tell you what to do are usually those who shouldn’t.

 

[Timbo]

The trunk will thicken a little every year. That is just how trees functions. The more foliage is above a certain part of the trunk, the more it will thicken.

I tried to write down my thoughts on this a while ago, but I am afraid I was not very clear. It is not a very popular article..

Why bonsai loose taper - Growing Bonsai

Understanding how growth affects taper in bonsai is important. Especially in early stages when growing out your seedlings to become bassive trunks for bonsai, this is important.

www.growingbonsai.net

Having a sacrificial branch near the base helps with that taper lose?
Yours makes more sense to me, I can't see how the base stops growing just because you chop. I didn't see in that article, roughly what do you think the leader size should be before you chop the 2nd time. 2/3rds seems like the taper would be mostly gone by the time you got the apex you want if the tree is in the ground. Lots of my trees are in the first/second chop window, so was curious.

 

[leatherback]

2/3rds seems like the taper would be mostly gone by the time you got the apex you want if the tree is in the ground.

It needs to be fairly thick.

A trunk with a radius of 1 inch will have a cut-surface area of 3.14 sq inch
A trunk with a radius of 2/3 inch will have a cut-surface area of 1.4 sq inch

I think this is exactly the point I tried to illustrate. To get the trunk to thicken to the full inch diameter from 2/3 inch, you need to more than double the amount of wood in the trunk: It takes a lot of growing to add to the diameter. You will not easily fill that last 1/3 inch. This is also why sacrifice branches seem to "do nothing" untill they are fairly near the trunk diameter.

A half inch radius branch will have a cut-surface area of just 0.78 sq inch. That is 1/4 of the 1 inch trunk cut-surface area. If you add these:

3.14 + 0.78 = 3.92 square inch. Solve that for radius = 1.12, so only 0.12 inch more, which is 12%.

This is all of course based on the assumption that we purely look at wood buildup without the plant actively steering which we no is not realistic

 

[treepirate]

It needs to be fairly thick.

A trunk with a radius of 1 inch will have a cut-surface area of 3.14 sq inch
A trunk with a radius of 2/3 inch will have a cut-surface area of 1.4 sq inch

I think this is exactly the point I tried to illustrate. To get the trunk to thicken to the full inch diameter from 2/3 inch, you need to more than double the amount of wood in the trunk: It takes a lot of growing to add to the diameter. You will not easily fill that last 1/3 inch. This is also why sacrifice branches seem to "do nothing" untill they are fairly near the trunk diameter.

A half inch radius branch will have a cut-surface area of just 0.78 sq inch. That is 1/4 of the 1 inch trunk cut-surface area. If you add these:

3.14 + 0.78 = 3.92 square inch. Solve that for radius = 1.12, so only 0.12 inch more, which is 12%.

This is all of course based on the assumption that we purely look at wood buildup without the plant actively steering which we no is not realistic

I never considered the maths of this before... Makes total sense though

 

[Zach Smith]

I just wanted to add a caveat to Zach's post. He's very experienced in bonsai and most definitely has the trees to prove it. That being said, as he is absolutely right that ground growing is light years faster than anything in a pot, one needs to keep an eye on the nebari as the trunk thickens. Because as the trunk thickens, so do the roots. You can add inches to your trunk girth in a few years in the ground depending on the species. Unfortunately, the opportunity cost of this is roots that soon grow beyond appropriate proportions. I most definitely grow things in the ground because it is so much faster to achieve a trunk size that's desired. It is necessary however to dig it up every two, three, four years and do root work to keep that nebari from getting away from you. Many people grow things in the ground on tiles to keep roots growing laterally and prevent them from diving straight down. Hope that helps!

Cory

Great point, Cory. Yes, ground growing is all about the trunks until the time comes when you decide to lift. Roots do what they want, too, so you can manage them along the way. If you dig periodically to cut back, the growth will slow for a bit. With regard to encouraging lateral growth using tiles, my experience for the most part is that trees planted out (meaning the tap has already been removed) grow their roots laterally without much special attention. But spreading out the roots of a seedling/cutting over a tile should definitely help avoid some of the odd growth we often see (roots coiling and crossing one another, for example).

 

[Timbo]

That's why I tile or put wood down in the ground, on some where the tap root was, new roots going in all diff directions. I end up cutting the bottom off bigger trucks again, otherwise it gets too deep for any future pot...maybe i'm doing something wrong. lol

 

[Larrytx]

It needs to be fairly thick.

A trunk with a radius of 1 inch will have a cut-surface area of 3.14 sq inch
A trunk with a radius of 2/3 inch will have a cut-surface area of 1.4 sq inch

I think this is exactly the point I tried to illustrate. To get the trunk to thicken to the full inch diameter from 2/3 inch, you need to more than double the amount of wood in the trunk: It takes a lot of growing to add to the diameter. You will not easily fill that last 1/3 inch. This is also why sacrifice branches seem to "do nothing" untill they are fairly near the trunk diameter.

A half inch radius branch will have a cut-surface area of just 0.78 sq inch. That is 1/4 of the 1 inch trunk cut-surface area. If you add these:

3.14 + 0.78 = 3.92 square inch. Solve that for radius = 1.12, so only 0.12 inch more, which is 12%.

This is all of course based on the assumption that we purely look at wood buildup without the plant actively steering which we no is not realistic

I have a question regarding Osage Orange Tree as it is called by some. I’m in zone 8B and in our area people call them Bois d Arc trees. The wood on these trees is very hard. Can they be trunk chopped?

 

[AcerAddict]

I don't know of any living tree on earth whose wood cannot be cut by a saw of adequate sharpness.