Trying to wrap my head around trunk thickening

Bp1313

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Hey guys, beginner here.

I keep hearing that in order to thicken the trunk of a tree, you have to put it in the ground.

What is keeping it from forming branches too high on the trunk as if it was growing normally?

For example I see some 10-15 foot tall redwoods outside near my house, and the first branch is like 5 feet up the trunk.

How do you plant a tree in the ground to thicken the trunk while still being able to make it a bonsai later?
 
You don't HAVE to put it in the ground. But the FASTEST way to get it to thicken up is to put it in the ground.

It is important to understand the concept of balanced growth above and below the soil level. If you want the top of the tree to grow fast and bulk up, you have to allow a corresponding amount of growth below the soil level (in the roots). When you place a tree in a bonsai pot, the reduction in space for the roots to grow will slow the growth rate of the upper part of the tree significantly. You can see this in nature, where trees growing in small pockets of soil in the mountains have barely any growth rate. Take the same tree out of the mountains and plant it in a field, and its growth rate will sky-rocket. So the fastest way to get the top of your tree to grow is to turbo-charge your root growth, and that happens best in a field or raised bed.
 
I keep hearing that in order to thicken the trunk of a tree, you have to put it in the ground.
Welcome. More foliage = more photosynthesis = more sugar production = fatter trunks (and branches). Ground growing typically gives the tree the most room to spread its roots and grow giant, but it is not required. Many of us (including myself) use larger grow boxes. You can grow the trees pretty giant in a grow box if desired.

What is keeping it from forming branches too high on the trunk as if it was growing normally?
Nothing, and that's what it will do. Sometimes they may shade out the lower branches but doesn't have to. My dawn redwood is over 10 feet and has still has very low branching. Ultimately, the tree gets chopped back hard anyway and new branches are grown lower down (at least on deciduous).

How do you plant a tree in the ground to thicken the trunk while still being able to make it a bonsai later?
Well, part of the answer is that growing the tree out is what is making it into a bonsai. With my dawn redwood, for example, I bought it as a stick in a small pot. I repotted it so the roots are radial and started to think what I would like this tree to be when it grows up. DR grow so quickly that I figured I could get a big bonsai out of this, maybe 2 feet tall. For this size bonsai, I will need at least a 4 inch trunk thickness at the base (1:6 ratio to the height). I basically have two choices here - (i) grow it huge until I gets close to 4" and chop it back hard and grow the next section; or (ii) use a cut and grow method over the years - both will get me to my goal with different pros and cons (a discussion for another thread).

Think of bonsai in 3 parts-
(i) nebari - from day one, you want to get this growing properly and continue that for the life of the tree (or at least your life)
(ii) Trunk development - Before you can really concentrate on branch work, you need to grow your trunk. The growth will give you what you need for size. Cutting will give you what you need for taper and movement. We are typically trying to encourage massive growth here so we can get to the next step a little "faster".
(ii) Branches - Massive growth and fine branch work just don't go hand in hand. So the real branch work will happen when we are ready to slow down the growth of the tree because we essentially have our trunk formed.
 
When I first started with bonsai, I envisioned many things that simply weren't true. One of them was that we maintain a nice looking tree throughout the process and one day magically it is a bonsai. This really is not at all what I actually found bonsai to be. We simply will not get where we want to be with the trees in our lifetimes if we approach the tree in this way. Rather, we need to use bonsai techniques to obtain the proportions in a small tree that would otherwise only appear on the tree when in full size. This will inevitably require cutting and growing and doing it again. The tree will spend many years overgrown, cut back and potentially with scars that need healing. Wires and wound sealant will be part of the tree at times.

"Temporary beauty is deliberately sacrificed for future quality. " Walter Pall.
 
You don't urgently need ground growing to thicken trunks unless you are looking to compete on thickness with Telperion or other famous field growers. Ground growing is the go-to answer for the easiest fastest way to make it happen, but not the only way to make it happen. There are plenty of us thickening trunks in other ways: Larger containers, stacking containers, use of airy containers, use of coarse aggregate media, and most importantly / most effectively out of all of these, the use of running growth.

People who ground grow are mostly putting that running growth into the ground. You can also send running growth into the sky if you want too. For illustration purposes see this photo I took a couple weeks ago, with a big "poodle" of a sacrificial runner powering a lot of wound-healing, post-repot recovery, bud generation, surplus energy for decandling, etc. Yes, I know, that trunk was mostly thickened in the ground originally, but if you have a poodle this big on a small conifer (as I do on many of my pines), then you can thicken trunks quite fast too. Stack containers (esp. in a climate that is mild enough for redwoods (assuming sequoia) like yours or mine) and ground growing actually starts to look like a hassle in comparison (albeit with some strong benefits if you can ride that rodeo skillfully). It does mean that you will have trees that can't be shown while you're developing them, but that's true of the ground-grown trunks too.


IMG_3745.jpeg

For your other question:

What is keeping it from forming branches too high on the trunk as if it was growing normally?

Those redwoods near your house had branches or could-become-a-branch-fronds 1 inch off the ground, 5 inches off the ground, 1 foot off the ground, 2 feet off the ground, and so on continuously as they grew to each successive size. They didn't form their first branch at 5 or 15 feet off the ground. They abandoned those small branches during the first few years of growth because they weren't viable. Why weren't they viable? Because the tree wants to be big by default and the roots are so unconstrained, and all the viable branches point UP. When they point up, they shade out fronds/branches below and win over those weaker parts. Weaker parts get abandoned, the strong get stronger.

So as a grower of a conifer trunk of a future bonsai, watching branches exist at heights that you want for a future design, you will need to ask yourself every season throughout the trunk-growing process "how will keep this branch viable? How will I ramify it before the window closes to ever do that?". The answer is that you need to work your conifers as they pass these points-of-no-return and do the necessary things to convert those "passed points of no return" into "opportunities taken advantage of just before the window closed". You need to wire those branches down, selectively weaken growth outside of the silhouette above, and shorten "keep" branches (borrowing a @Brian Van Fleet term) occasionally to prevent them from having interior growth out-muscled by exterior growth of their own. The mistake would be to blow past these various points of no return (whether for the whole tree or for individual branches) and magically expect back budding to save the tree later on. It can in some cases, with redwood too (depending on what "redwood means"), but not always/usually/often.

This is just the tip of the iceberg though. Ideally you figure out who in the bonsai community is doing this kind of work and study what they're doing carefully at every stage, because there are a lot of details depending on which species you're growing. With conifers the urgency to act on opportunities is higher than with deciduous broadleaf, moreso if you are growing shohin. But there are folks who are thickening trunks in containers and also managing to keep future branches under control while not impeding vigor.

Keep your eye on growth and always be asking questions like "am I missing an opportunity to strengthen something that's about to get weakened?" and "why would this shoot be weaker than that other shoot? what can I do to make it more successful?". Even during trunk growing these are relevant questions, and this is truer the smaller your target design size is.
 
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When I first started with bonsai, I envisioned many things that simply weren't true. One of them was that we maintain a nice looking tree throughout the process and one day magically it is a bonsai. This really is not at all what I actually found bonsai to be. We simply will not get where we want to be with the trees in our lifetimes if we approach the tree in this way. Rather, we need to use bonsai techniques to obtain the proportions in a small tree that would otherwise only appear on the tree when in full size. This will inevitably require cutting and growing and doing it again. The tree will spend many years overgrown, cut back and potentially with scars that need healing. Wires and wound sealant will be part of the tree at times.

"Temporary beauty is deliberately sacrificed for future quality. " Walter Pall.

Wish I could be this concise and effective with my attempt :D
 
Thanks all. This is very helpful and is giving me lots of good homework.

Would you wire for trunk movement while it’s in the ground developing a thick trunk? I suppose at some point it will get too thick to wire.
 
Would you wire for trunk movement while it’s in the ground developing a thick trunk? I suppose at some point it will get too thick to wire.

Indeed, too thick to wire is one of those points of no return, so you do it when the window is still open. Also applies to root work. Before a long stint of high-vigor trunk growing, you want to have your nebari sorted as much as possible. It's a big hassle to correct that later (if it's correctable at all).
 
We need to differentiate between trees that produce buds from bare wood after pruning and those that can only bud from live foliage.
Most deciduous species can be chopped low and still grow again so it does not really matter if branches are 2 or 3 m from the ground at some stages of development.
Many conifers cannot grow new shoots on older, bare wood. In this case growing needs to be slower and controlled. Sacrifice branches or regular chop and grow cycles are usually used with pines, junipers and other trees like this.

Need to be very careful when wiring rapidly growing trunks or branches. Fast thickening trees will develop wire marks or swallow the wires completely before you realize it is happening.
With trees that shoot from bare wood I often develop bends by chop and continue the trunk with a new shoot. These bends often appear much more natural than wired bends anyway.
When growing conifers I usually put the bends in while the trees are still young and in pots then transfer to the grow beds to thicken. Also use strategic sacrifice branches to thicken particular sections of trunk or branch.

Not every bonsai need to be a thick trunk sumo. Delicate trunks can also be beautiful.
Not every bonsai needs to be grown as fast as possible. There can be major drawbacks to fast growth and not every fast grow trunk will be worth going on with. Sometimes slower development is a more sure bet and may even get you there quicker in the end.
 
Welcome. More foliage = more photosynthesis = more sugar production = fatter trunks (and branches). Ground growing typically gives the tree the most room to spread its roots and grow giant, but it is not required. Many of us (including myself) use larger grow boxes. You can grow the trees pretty giant in a grow box if desired.


Nothing, and that's what it will do. Sometimes they may shade out the lower branches but doesn't have to. My dawn redwood is over 10 feet and has still has very low branching. Ultimately, the tree gets chopped back hard anyway and new branches are grown lower down (at least on deciduous).


Well, part of the answer is that growing the tree out is what is making it into a bonsai. With my dawn redwood, for example, I bought it as a stick in a small pot. I repotted it so the roots are radial and started to think what I would like this tree to be when it grows up. DR grow so quickly that I figured I could get a big bonsai out of this, maybe 2 feet tall. For this size bonsai, I will need at least a 4 inch trunk thickness at the base (1:6 ratio to the height). I basically have two choices here - (i) grow it huge until I gets close to 4" and chop it back hard and grow the next section; or (ii) use a cut and grow method over the years - both will get me to my goal with different pros and cons (a discussion for another thread).

Think of bonsai in 3 parts-
(i) nebari - from day one, you want to get this growing properly and continue that for the life of the tree (or at least your life)
(ii) Trunk development - Before you can really concentrate on branch work, you need to grow your trunk. The growth will give you what you need for size. Cutting will give you what you need for taper and movement. We are typically trying to encourage massive growth here so we can get to the next step a little "faster".
(ii) Branches - Massive growth and fine branch work just don't go hand in hand. So the real branch work will happen when we are ready to slow down the growth of the tree because we essentially have our trunk formed.
These big picture explanations are the gold that I’m extracting from this mountain of information that is Bonsainut. Your comment puts this all in perspective for me. I cherish it!
 
More foliage = more photosynthesis = more sugar production = fatter trunks
I feel the need to comment on my own post, because while this is probably a good 30,000 foot view, it may not tell the whole story. I sometimes wonder about those bonsai with really nice canopies and tons of foliage - why is pinching (and the like) more or less sufficient to prevent large amounts of trunk thickening if it has so much sugar producing foliage? I am starting to believe that it is actually a combination of foliage and extending shoots that encourages big growth.
 
I am starting to believe that it is actually a combination of foliage and extending shoots that encourages big growth.
It is. Certainly longer sacrifice branches add weight and pressure which the tree compensates for. It is not just the amount of sugar produced, it is also the scaffolding needed.
 
It is. Certainly longer sacrifice branches add weight and pressure which the tree compensates for. It is not just the amount of sugar produced, it is also the scaffolding needed.
Definitely reaction wood is one of the fastest expanders of tree growth. When we look at the rings in felled trees, it isn’t uncommon to see ‘good’ growth years within the rings showing as significantly wider annual rings than usual, but if you see one where it has been colonised by decay fungi (specifically white rot) for example, the loss of stability in the trunk and resulting reaction growth send those rings phenomenally wide.

Translating down to bonsai, I often wonder if attaching flags or sails to the trunk or branches to increase wind movement might dramatically enhance trunk thickness growth rate (but the risk of over egging it and watching a tree sail off over the fence seems too real ;-)
 
attaching flags or sails to the trunk or branches to increase wind movement might dramatically enhance trunk thickness growth rate (but the risk of over egging it and watching a tree sail off over the fence seems too real
I feel it is one of the main reasons why top extensions are so usefull. I have piles of bricks on pots with long whips, yet at times even 2ft wide pots blow over, illustrative of the pressure on lower trunk and roots.
 
I often wonder if attaching flags or sails to the trunk or branches to increase wind movement might dramatically enhance trunk thickness growth rate
Query whether weights could accomplish the same. I had some weights on a tree last year to bend the trunk and could swear the trunk chunked up.
 
Query whether weights could accomplish the same. I had some weights on a tree last year to bend the trunk and could swear the trunk chunked up.

This is likely to be the case, where the tree puts on reaction growth to correct an abnormal load.

This could potentially be used to make relatively fine-tune adjustments to trunk thickness and taper, when you consider that broadleaf trees lay down reaction wood primarily on the tension side - attempting to pull the trunk back straight, whilst coniferous trees do the opposite - forming wood to push on the compression side.

If only I had enough spare time to experiment with this!
 
Query whether weights could accomplish the same.
I would not be surprised. I think mos of us have seen very quick beefing up of branches that were heavily wired, leaving us in surprise how quickly things started to bite in. I am pretty sure trees respond strongly to the pressure put on any part of the tree.
 
I understand the science behind running your hand over the tree to mimic wind, creating minute stress on the trunk, so the tree “repairs” the stress and the trunk slowly thickens. Go out there every few days and do that. It’s actually relaxing and helps the trees get stronger.
 
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