Deshojo Japanese Maple Trunk Taper

[zebes]

Hi - I've got a Deshojo Japanese Maple and I'm currently trying the thicken the trunk to twice the size it is currently. Should I be chopping the trunk to create taper now along with the sacrifice branches (been growing for 3 years) or do I leave everything as it is and just plant in a larger pot next growing season?

Thanks

Mark

[shibui]

Leaving the trunk as is and letting the tree grow will thicken the trunk but it will not give taper. The whole trunk will get thicker. At some stage you then need to chop the trunk and grow a new leader to make some taper. Good taper usually requires that grow and chop cycle several times.
A really thick trunk without taper that is chopped will leave a large cut. That large cut can take many years to heal over and will often rot out before it heals properly.

I prefer to do more regular smaller chops. I find that the trunk taper is usually much better, cuts are smaller so they heal in just a few years, often before the next section has grown. After a chop I often get several new leaders instead of just the one - essentially several vertical sacrifice branches. All those are allowed to grow and end up adding just as much thickening as one single thicker one but as they are growing from different places the thickening is spread out and I get better taper. Having several leaders also gives me more options when pruning to look for a more attractive trunk line by selectively removing some but leaving others.

A larger pot will usually give you more growth and therefore more rapid thickening. You could do a trunk prune and repot up into a larger pot this winter to speed up development.

You can see some of the trident maples I grow in grow beds at Shibui Bonsai.com.au - https://shibuibonsai.com.au/?p=1721 or https://shibuibonsai.com.au/?p=1458

Growing Japanese maples is similar but just a little slower. Growing them in pots also follows similar lines but adds a few more years to the process.

[zebes]

Thanks for the advice shibui, in that case I'll do a chop in winter and repot if it means better quality long term. Where would you suggest I make the cut? I've drawn a red line where I'm thinking of doing it.

[shibui]

There are so many possible chop spots and budding is sometimes random so there is no right answer, only possibilities.
I looked at your proposed chop spot too. It gets rid of a couple of scars and could enhance the trunk curve if shoots pop right. On the downside there is a strong branch growing to the side there. Sometimes if there is an existing strong branch the tree will put out less new buds as it already has a good avenue for growth. There is a possibility that the tree might just use the branch and not make buds. That branch looks like it is heading in the wrong direction for a trunk leader.
I'd probably be inclined to be a bit more conservative first up and cut higher. I'm looking at above a thinner branch just above those 2 half healed scars. That looks like a better trunk line but bear in mind I can only see a 2D image so real curves are not apparent. The existing scars won't be there too long if the trunk gets a chance to grow a bit. The existing trunk bends look good. There is a good possibility the trunk will produce lots of buds lower and you would then have known options to cut lower in another year or 2.
As mentioned, with plants and bonsai nothing is certain, only possibilities and probabilities.

[zebes]

Could I just remove the side branches to push growth to the top? If not, I can leave them to gain more taper in those areas. I've painted in black how the trunk line can go in the photo below.

As you say, I can also wait for other buds to appear lower on the trunk and chop further down later if there's a new leader I want.

I appreciate the advice!

[Max]

I would also suggest tilting the pot at different angles. This will give you more choices for better movement when you decide where you want your cut.

[zebes]

Thanks, I'll try tilting to see what my other styling options are.

Shibui - should I do a root prune at the same time or will that slow down growth in the next season?

[shibui]

Contrary to popular belief I have not found that root pruning slows growth. In fact I find the opposite in my bonsai. In the season following root pruning and repotting my bonsai grow far more vigorously.
A really heavy root prune of a developing tree may slow it down for a few months but the advantage to development of a great nebari outweighs and reduction in trunk growth. Good nebari is equally important as good trunk on maple bonsai. Having one without the other is only having half a bonsai. Developing one at a time could double the time taken to get to show status so I elect to do both at once.

That trunk line in black is exactly what I indicated. Just make sure it looks good in 3D before going ahead. Leave the lower branches to grow as sacrifice branches. It is highly unlikely that they will still be suitable for the final bonsai when the trunk has grown enough but can always be removed at that stage. New shoots grow from the base almost every time a branch is removed from JM so very reliable to replace thick or straight branches when the time comes. try to avoid large sacrifice branches growing from the front side of a trunk as large scars can take a while to heal over during the slower branch and ramification development phase later.

[zebes]

I'll do both the chop and root prune if it means having a better quality tree in the long term instead of pushing for only trunk size.

You've been a big help, thank you.