How to bend the trunk

Hello everyone, I thought I would ask for advice with my maple:



As you can see, in the middle of the tree, the trunk is too straight and then it bends to the right on rather too aggressive angle. What I want to do is to give the trunk a bit of a movement and soften the angle of the upper part. I made a quick virtual of want I want to accomplish.



Now, how do I do this?  The trunk is too thick for simple wiring so I guess I'll need to use some more sophisticated technique like maybe using some rebar or something like that but I never did this before, so what would you sugest? And when is the best time to do it?

Thanks for help

Vitusus

It looks like you are planning a fairly shallow bend in a fairly small trunk (about 1 cm or a bit larger). Can you bend the trunk the way you want it with your hands/fingers? if so then you should be able to use heavy wire to hold the bend. I would slightly over bend to compensate for spring back.

If the trunk is too stiff to bend by hand I frequently use a stiff bar and a piece of wood on the inside of the bend. I will resort to the old IBC method using characters since I don't feel like drawing and scanning a picture. Plus some of the folks like me from the 1980s IBC may appreciate the retro look!

|||
||\
|| \
|| \
||==|
|| /
|| /
||/
|||

This stiff bar (I use rebar) is marked with the ||, the piece of wood as =, and the trunk as | or \ or /. Use strong wire (copper or steel is best) and some padding to pull the trunk back towards the stiff bar to create the bend.

Marty

Hi Marty,

Thank you for the guide and nice schematics, I think I get your point. Few more questions:

1) As the trunk is almost 2cm thick, I am not having enough strength in my arms to bend it (maybe I should have but I don't ). So I will have to use a rebar as you suggest. If you look at my "virtual", you can see that I need firstly bend it slightly to the left and then back to the right. Is it possible to do it with one rebar only at the same time or will I have to combine two rebars and/or do this in steps, so firstly bend it to the left and later on bend to the right?

2) When is the best time to do it?

Thanks

Vitusus

You will need two bars to make two different bends. I would do the lower one first and most likely anchor it to the pot with guy wires to stabilize the construction before doing the upper one.

Make sure to pad the contact points, particularly the wire pulling the tree back to the bar. I like to use pieces of bicycle inner tube for pads and add 6 mm irrigation tubing that is fairly stiff around the wires where they press on the tree.

You can use just about any style of clamp to assist in making the bend. They make specialized bending jacks, but I have used wood working clamps. You can also enlist the help of a friend with one of you using both hands to squeeze the trunk and rod together and the other pulling and twisting the wire to hold it in place. Be careful with any of these techniques since you can easily snap the trunk if you try to bend it too far too quick. If the bend is severe (yours appear to be subtle), you may want to do the bend in a couple of stages a few days apart. However, there are those who advocate that flexing the trunk/branch a bit too loosen it up and then doing the bend at one time is less stressful on the tree.

After the first flush of growth has set seems to work fairly well for me. The major expansion of the trunk has been done for the year and the wood is not frozen or otherwise too rigid.

Cut it down and regrow the next section.
Not only is the trunk straight but it lacks taper.
Chop and grow techniques take care of both problems.

Good point about how to develop the tree. wiring the second branch on the left up a bit and copping just above it would be good. I would cut it a full diameter above the branch and let the new leader become established before cutting it back further.

M. Frary wrote: Cut it down and regrow the next section.
Not only is the trunk straight but it lacks taper.
Chop and grow techniques take care of both problems.

Ok, considering this as an option, when is the right time to cut it?

I would cut it now assuming you are in the now assuming it is early summer for you. Get the new leader wired up (gently so you don't break it) and it should take off and grow strongly. If you get any buds below the new leader (you should on a maple), let them grow for a year or two to thicken the lower trunk a bit.

Marty Weiser wrote:I would cut it now assuming you are in the now assuming it is early summer for you. Get the new leader wired up (gently so you don't break it) and it should take off and grow strongly.

Yep, it's first summer day today here. Ok, will probably do it, I need to learn these hard pruning techniques anyway and what better material to learn it on than a maple, right

Why bend it like that?  You already have a great curve at the top, and you don't need to change that?  If you bend the middle/bottom you will achieve a lot of movement on the trunk?  

2017-06-22_09-21-39 by BrendanR2012, on Flickr

You'd need only one bend as the top would be curving away from the new bend anyway?

BrendanR wrote:Why bend it like that?  You already have a great curve at the top, and you don't need to change that?  If you bend the middle/bottom you will achieve a lot of movement on the trunk?  

2017-06-22_09-21-39 by BrendanR2012, on Flickr

You'd need only one bend as the top would be curving away from the new bend anyway?

Brendan, how exactly should I achieve what you drew with one bend only? I see two bending points, one at the bottom and other in the middle of the curve you drew. Or should I put there two pieces of wood (one to the top and one to the bottom) and then apply pressure to the middle part, that is what you meant by one bend only?

Is the trunk straight when seen from the other angles, too?

Yes, the part from the beginning to the end of the curve drawn by you is straight from all angles.

If the trunk is straight you can use a simple bending brace to bend it.  Don't cut off any growth as it is needed for helping bends to set.

Start by wrapping the tree in heavy protection at the bend points.  Inner tube wrapped super tight.  Held in place with zip ties.  

For the brace you might try two lengths of timber about as long as the trunk.  

Put one on either side of the trunk and secure them together against the base of the tree and to each other.  I'd use wide enough lengths so that I could screw them together around the trunk.  I'd probably put  screw right through the trunk for good measure.  They have to be immobile as they are the fulcrum for the bends you will do.

At the point of the first bend you attach a cross piece to the timber brace.  You will be bending the trunk over this so make sure the cross piece is strong and properly secured.  Perhaps a bit off a broom handle screwed into the timber braces?

The critical point is that the trunk below this bend has to be completely secured in place against the brace.  

2017-06-23_11-36-35 by BrendanR2012, on Flickr

Then you can bend the trunk over this first brace.  DO IT SLOW!  Stop if you hear any cracking.  Slip a bit of wood behind the trunk against the lengths of timber and slowly work it down.  Do not over-pull on the trunk.  The trunk will be bent out to the one side.  Temporarily anchor it in place.

Then fit the second cross brace for the second bend.  

2017-06-23_11-37-33 by BrendanR2012, on Flickr

Repeat for the third

2017-06-23_11-38-29 by BrendanR2012, on Flickr

Lock it in place with a fourth cross brace

2017-06-23_11-49-55 by BrendanR2012, on Flickr


Seen from the side it would look like this:


2017-06-23_12-46-18 by BrendanR2012, on Flickr

Let is set for about 2 seasons.

Thank you very much, Brendan, for detailed guide, now I only have to get myself some nice wood pieces to build the construction you described

I'll post some pictures when I get to doing that

Bonsai from Acer pseudoplatanus should be designed as a tree over 50 cm. Well, at least in my opinion. The main reason is the size of its leaves and willingness of this species to cooperate on their size reduction.

The proposed actions make the tree look much more like a viper in a swing than a natural looking tree. Do not get me wrong - the method itself is OK it is just about the execution.

While I fully respect your your way of moving this tree forward for my liking I would follow the way proposed by Mike Frary. Chop and grow. I would only add to that: Air layer next year and if possible place in the ground.

Whichever way you pick - have a fun and do not kill the tree.

Vlad wrote:Bonsai from Acer pseudoplatanus should be designed as a tree over 50 cm. Well, at least in my opinion.   The  main reason is the size of its leaves and  willingness of this species  to cooperate on their size reduction.  

The proposed actions make the tree look much more like a viper in a swing than a natural looking  tree.  Do not get me wrong - the method itself is OK it is just about the execution.

While I fully respect your your way of moving this tree forward for my liking I would follow the way proposed by Mike Frary.  Chop and grow.  I would only add to that:  Air layer next year and if possible place in the ground.  

Whichever way you pick - have a fun and do not kill the tree.

Hi Vlad, thank you for your opinion. The highest point of the tree is already at some 46 cm, so I should have no problem reaching the proposed height. I actually agree with you that there might not be need for so many bends and I might try to stay with two instead of tree bends. Anyway, I want to try this technique and if it does not look ok, I can chop it anytime but the bending cannot be done once I chop it We'll see.

Not killing the tree is obviously my first priority.

The bends are quite stressful just for itself. The temperature around 30°C as it is now really doesnt help to ease it. I hope you will wait few days for the cooler days or keep the tree in the shade and keep the surrounding ground wet to increase the humidity. Good luck.

The highest point of the tree is already at some 46 cm, so I should have no problem reaching the proposed height.


The height/trunk width at the ground level ratio should be  around  6/1 ie for a tree of 50 cm you should have a width of 6 - 8 cm to get a look of matured tree.  At the same time the tree should have a decent taper.   But frankly it is not a problem to have the ratio of  20 to 1 if you are happy with that.  

Otherwise: Grow, chop, grow... is one way.  Reasonable yamadori is the other one.

BrendanR wrote:If the trunk is straight you can use a simple bending brace to bend it.  ... ...
Put one on either side of the trunk and secure them together against the base of the tree and to each other. ... ...
Then you can bend the trunk over this first brace.  DO IT SLOW! ... ...
Then fit the second cross brace for the second bend.
Repeat for the third
Lock it in place with a fourth cross brace
Seen from the side it would look like this:
Let is set for about 2 seasons.

Brendan, thank you for taking the time for the detailed instructions.
This is the first time that I come across this type of bending procedure!

Vlad wrote:Bonsai from Acer pseudoplatanus should be designed as a tree over 50 cm. Well, at least in my opinion. The main reason is the size of its leaves and willingness of this species to cooperate on their size reduction... ...
While I fully respect your your way of moving this tree forward for my liking I would follow the way proposed by Mike Frary. Chop and grow... ...

I would say the same.
The tree will gain taper quickly and better proportions.

Well, I tried to bend it, it did not look good, so I did as suggested and chopped it down. Now, as you can see, there is one branch that might be wired up as a new apex but I also have a small bud there that is actually in better position in my opinion, so I am tempted to wait for that one and wire it up when it grows a bit.