Trunk development on young red Japanese maple - to prune/defoliate or not?

[zeejet]

I obtained an inexpensive red maple from Brussel’s Bonsai in January and I would say I was pretty lucky to score this tree for only $50. It budded profusely and has had very vigorous growth since early March.

It’s relatively young and has a thin trunk (⅝”) that I’d like to thicken to at least 1” caliper before moving into chopping for taper development.

I’m not entirely sure what to do right now. My impression is that I should just let it grow unimpeded and only prune back slightly during winter to setup for next season. However, the density of the foliage might be depriving the inner sections of sunlight, which could lead to interior dieback. I also hear that pruning can initiate a second flush of foliar growth, which would continue to contribute to trunk thickening.

The plan next spring is to revert back to a growing container (grow box or 2-gallon pond basket) during repot to put it on a faster growth track.

What would you do in this situation?

 

[Bonsai Forest]

Excellent tree

 

[River's Edge]

I obtained an inexpensive red maple from Brussel’s Bonsai in January and I would say I was pretty lucky to score this tree for only $50. It budded profusely and has had very vigorous growth since early March.

It’s relatively young and has a thin trunk (⅝”) that I’d like to thicken to at least 1” caliper before moving into chopping for taper development.

I’m not entirely sure what to do right now. My impression is that I should just let it grow unimpeded and only prune back slightly during winter to setup for next season. However, the density of the foliage might be depriving the inner sections of sunlight, which could lead to interior dieback. I also hear that pruning can initiate a second flush of foliar growth, which would continue to contribute to trunk thickening.

The plan next spring is to revert back to a growing container (grow box or 2-gallon pond basket) during repot to put it on a faster growth track.

What would you do in this situation?

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I would let it grow unimpeded. Next spring I would begin with a repot to begin improving nebari, plant in a large grow box or Anderson flat and focus on developing a thicker trunk. Before chopping I would create a plan. What is your goal for thickness, overall height of the tree, preference for branch placement. Do you intend to use any of the current branching, movement or taper in the development? Or is it your intention to start from scratch and rebuild the tree? Advice should be appropriate for the intended outcome. Just a thought.

 

[zeejet]

I would let it grow unimpeded. Next spring I would begin with a repot to begin improving nebari, plant in a large grow box or Anderson flat and focus on developing a thicker trunk. Before chopping I would create a plan. What is your goal for thickness, overall height of the tree, preference for branch placement. Do you intend to use any of the current branching, movement or taper in the development? Or is it your intention to start from scratch and rebuild the tree? Advice should be appropriate for the intended outcome. Just a thought.

Thanks for the suggestion on growth - I'll likely let it go untouched this entire season and focus on water, fert, and sun management.

I'm not looking for a very high trunk to height ratio and perfectly OK with a more delicate look (maybe around a 1:10 trunk to height ratio). I would like to keep the lowest 2-3 branches if possible and aim for a trunk thickness of about 1.5".

As for nebari, there's a high root extending out (extending toward the viewer in first photo and towards the back in second photo) that I may end removing or ground layering depending on the root structure below (will see during repot next season).

Otherwise, I have not thought a lot design in detail for this tree. I think my tastes will change and evolve quickly as I'm only in my first year of practice. I guess I'll return to this topic in winter after leaves fall and any dieback happens to see the branching structure. It's a bit hard to tell what is useable and what's not moving forward right now.

 

[Shibui]

'Interior die back' is no problem at this stage as JM will bud well after pruning back to older and bare wood. Instead of calling it interior die back maybe think of it as a lack of active shoots but still plenty of dormant shoots ready to go when the opportunity arises. In any case the trunk chop you refer to for taper is likely to remove most of the current trunk and branches. I'd be looking at that first branch as possible new leader after a chop - or something similar.

Be a bit wary of thickening the trunk to full thickness before the first major chop. After a chop you'll usually need to grow a new leader which may take 2-5 years to match the thicker stump you've just grown and grow branches. That lower trunk will still thicken during those subsequent leader development years so chop and branch development can start a bit before the lower trunk reaches desired size.

Nebari is very important for JM bonsai so root work is a priority at the earliest opportunity. Even if you need extensive root work and believe that root pruning may slow trunk thickening I'd still do it. IMHO nebari development trumps trunk thickening in JM development terms.

Apart from a very broad aim I've found there's not a lot of point making style plans for trees in the early stages of thickening because the trunk size and shape can change hugely in the development years. A plan may help guide what you do but be prepared to change as the tree does.

The vast majority of fast grown JM end up with branches that are way too thick for the trunk. Be prepared to chop most or all branches after the trunk thickening phase in order to develop new branches with better scale.

 

[zeejet]

Be a bit wary of thickening the trunk to full thickness before the first major chop. After a chop you'll usually need to grow a new leader which may take 2-5 years to match the thicker stump you've just grown and grow branches. That lower trunk will still thicken during those subsequent leader development years so chop and branch development can start a bit before the lower trunk reaches desired size.

I have heard this philosophy and seen suggestions like chopping at half the desired thickness (in my case, probably close to 3/4" or almost 1" before the chop). It'll be sad to see all that top branch growth get removed, but that's the cost of doing business I suppose. I'll enjoy it for now and say goodbye when the time comes.

Nebari is very important for JM bonsai so root work is a priority at the earliest opportunity. Even if you need extensive root work and believe that root pruning may slow trunk thickening I'd still do it. IMHO nebari development trumps trunk thickening in JM development terms.

I'm slightly worried about this as the current nebari looks a bit odd and uneven. It's hard to tell for sure what I'm working with until repot next spring so I'll check back in next season on this progress.

 

[River's Edge]

You may consider improvements to what you have rather than extreme measures usually reserved for trees in earlier stages of development.

 

[Shibui]

Frank's last advice is good.
Decide whether you want to maintain the current shape/style or sacrifice years of work for an ideal that will take many more years and may or may not be achieved.
'Extreme measures' can be applied at any time in the tree's life. Sometimes it make s a huge difference to the quality of the bonsai but you need to be prepared for the time, effort and possible failure from that work.

 

[zeejet]

You may consider improvements to what you have rather than extreme measures usually reserved for trees in earlier stages of development.

Frank's last advice is good.
Decide whether you want to maintain the current shape/style or sacrifice years of work for an ideal that will take many more years and may or may not be achieved.
'Extreme measures' can be applied at any time in the tree's life. Sometimes it make s a huge difference to the quality of the bonsai but you need to be prepared for the time, effort and possible failure from that work.

This is an interesting perspective as I think the community and expert blogs tend to push for perfection and “taking action” when it comes to development. I suppose I can make this decision later, but its good to know that it’s OK to leave it as is if I so choose.

If I choose to leave it largely as-is and grow it out, I would still need to prune back and develop branching eventually, correct? I imagine the tree will have a lot less taper and I will need to make up for it in other areas like nebari, branch and foliar development.

 

[River's Edge]

If you choose to work with the existing general shape. Which is what I would do with this cultivar and this particular specimen. Then I would focus on improving the nebari over time as well as managing the growth of the existing primary branches I wish to keep along with developing the overall form and new branching. Please keep in mind that with the growth habits of red maple it would be easy to thread graft branches where desired. This is where retaining existing growth is a benefit when one is unsure and still deciding.
How about some measurements to aid decision making. For example what is the distance between the existing nebari and the first branch? This would be one of the most important reference points to consider in decision making. How tall would the tree have to be if you tripled that distance for example?
Also it would be helpful to know the cultivar as that provides more information as to expected growth habit and also node length. More appropriate sizing and style can be informed from natural growth habit. There are a lot of excellent bonsai trees with more slender styling!
I guess when it come right down to it, I favour a decision based on exploring all the options first.
If you need the lower portion to be shorter and the nebari needs improvement that can be accomplished with an air layer, no need to lose the upper development which looks quite nice at this point to begin ramification.
One further question. Is that wire on the trunk or wire marks from previous work?