Preventing Inverse Taper

[canoeanu]

Hello all. I'm a huge plant nut. My husband got me a tree to "begin" my bonsai journey. I realize every tree is a very unique journey. I struggle with it because the type A part of me wants a clear order of operations (you'll notice...). I know the general path people take for a deciduous bonsai tree, but my husband gifted me a unique tree that he picked out from a nursery with some unusual features that make this complicated for me.

Its a shishigashira and it looks to be around 3-4 years old.

There is probably 6 inches on the original trunk before it was cut back hard and a branch took over the trunk. From that cut back, there are a lot of new branches, which is great for now. Eventually I'll have to make some decisions about these branches, but I'd like to put that off for as long as possible. My immediate goal is to thicken the trunk, especially the lower part, to prevent an inverse taper and to create a more dramatic trunk base. I worry if this section of the trunk isn't thickened, its very likely to go inverse further up on the trunk. However, there isn't a single branch in that lower part of the trunk to use as a sacrificial branch. I need to figure out how to encourage that to bud.

Bury it or pot it?
I'm having difficulty deciding which one is best. If I bury it, it will be in the only spot I have available. probably imperfect but alright lighting. I know it will stay moist longer. I know it will thicken faster. But you run the risk that you have to do drastic root pruning to get rid of the feeder roots and make that nice radial structure. If I pot it (I was thinking large basin style pot with the right organic soil mixture for Japanese maples, so plenty of room to grow), I can clean up the roots before potting it. I can move it to the perfect lighting. but this method is slower than in ground, which isn't too big of a deal. Main con: I don't know if this method will be enough to encourage a new shoot at the base of the trunk to be a sacrificial branch.

Cut back branches/foliage?
What do I need to cut back in order to encourage branches to develop on the lower trunk? Is it bad to consider pruning (with cutpaste) if I know I have to clean up the roots and pot it?

In general:
I can't seem to figure out how to encourage a brand new branch to grow on the lower part of my tree.

 

[sorce]

Pics!

Where you at?

Welcome to Crazy!

Sorce

 

[Harry Bushwhacker]

I’m fairly new to bonsai as well, however I believe some people place a tile or plate of some sort under the tree to force the roots to spread out. One thing that is for sure, pictures of the tree will help

 

[canoeanu]

Photos as requested. We are in Texas so I need to keep her near the cooler side of the house that has adequate sunlight. If planeted, there is only one spot in my garden that is cool enough but may not have adequate sunlight and another that is full sun. It I worry about it being too hot.

I cannot for the life of me figure out how to get the pics upright. I tried rotating before uploading. Ugh. Sorry

 

[canoeanu]

I’m fairly new to bonsai as well, however I believe some people place a tile or plate of some sort under the tree to force the roots to spread out. One thing that is for sure, pictures of the tree will help

I have to amend the soil greatly to improve drainage. Very clay ridden my area and it only takes a heavy rain for the water to accumulate. I worry about tile for drainage purposes. I watched a YouTube video on what is called the “escape method”. I would link it but I don’t know if it’s against the rules.If you google escape method and look for a Philippine-based video about trunk thickening for beginners you’ll see it. I wonder if this could be the solution.

 

[sorce]

Sorry

No worries.

I wouldn't worry about too hot as much as too sunny and too much drying wind.
Shade cloth and wind block.

Second thought. Them black rocks probly get hot enough to create "drying".

Sorce

 

[canoeanu]

No worries.

I wouldn't worry about too hot as much as too sunny and too much drying wind.
Shade cloth and wind block.

Second thought. Them black rocks probly get hot enough to create "drying".

Sorce

I’m glad you mentioned this. It’s something I’ll look out for. Rolling some thoughts off the top of my head: we live in Houston so it’s massively humid. This particular area is covered in granite rock to improve drainage, it’s a particularly wet spot if it were lawn or pavers. I would worry about reflective rays/heat from the granite. However I can only vaguely remember those stones stating fairly cool because of the way the light hits that area. It’s shade for intermittent parts of the day. I’m in zone 9a but keep zone 7-8 plants here and they thrive.

again I’ll pay attention. So glad you mentioned it.

 

[Forsoothe!]

How about the best of both worlds: repot in a vessel size that you want to be the finished bonsai size. Sink that in a large terracotta and leave it in there for 2 growth seasons, but not 3. Some roots will escape your pots through the drainage holes by the end of second season, but you will have substantial roots left inside your pot. Do this same procedure until you're happy with the size. The best growth will occur in year #2. Do not let it go the third season because all of that season's growth will be outside your pot and roots inside will be too packed. So repot this spring and repot again in spring 2022, ad infinitum.

You need to cycle your photos through a photoshop program of some kind. I use Corel Photo House from 1997, so even caveman age software is useful. I reformat to 8" high and 186 pixels .jpg and they load well and fit my screen for background when I like the picture. Your rotation problem may reflect that you are holding your camera upside-down if it's a cell phone. (That's what happens with mine, it will take a picture held in all four attitudes, but two are wrong.)

 

[Shibui]

The point you are assuming was a cut back is probably the graft point. Below that it will be normal seed grown Japanese maple. Above is shishigashira. The original growers have probably worked hard to make sure that the rootstock has had buds removed so it does not sucker. If you can get buds there you will need to manage them because they will grow much faster than the grafted part and there is a risk that the shishigashira can be swamped and die.
Shishigashira is a dwarf form and tends to grow thick, straight shoots so will need pruning to make it branch and ramify. These dwarfs are not the easiest to work with because of the way they respond to pruning with clusters of shoots close together.
Good ground growing position will usually produce greatest trunk increase but sub optimal conditions will reduce growth rates to the point where better container cultivation will give better growth. Hard to predict where the balance point lies until it is tried.
Also be aware that ground growing has risks. Fast grown trees can become stiff and ugly very quickly. Reverse taper occurs much faster and is difficult to remedy. The point where your trunk branches into a cluster of branches just above the graft is a potential point where excess thickening will occur. Choices of trunk and branches need to be made before problems become evident.

As you don't have experience with ground growing I would recommend using a larger grow pot so you can maintain some control. A slower grown good tree is far better than a thicker ugly one.

JM can, and should, be pruned. Pruning will force some badly needed lower shoots. Left alone the tree will continue to grow tall and straight. Generally new buds will sprout close to pruning cuts so you really need to cut just above where you want new branching. Usually several buds sprout and grow. 1 becomes the side branch, another is allowed to grow as the trunk extension. Hard pruning is often necessary with Japanese maple. There is no problem with pruning the branches and the roots in the same season. I usually do both at the same time - repot and prune roots then shape the top while I have it out of the pot because it is important to see how the main surface roots relate to the trunk in order to make better pruning choices. It is also easier to rotate and angle the trunk without the pot and soil.

 

[Leo in N E Illinois]

Two thoughts:
Maples in Houston - I would keep yours in a pot, because you can move it around according to season, heat and sun. In autumn through winter into spring, the maple will tolerate up to full sun. In the heat of the summer, you will want to site the maple in afternoon shade. Having the tree in a pot or a grow out container, allows you to move it around. Also being in a pot, you can set it on a block, shelf or table to get it off the ground if drainage is becoming a problem. My preferred growing out container is an Anderson Flat. It is a heavy plastic container, with a mesh bottom. The size I like is 16 x 16 x 5 inches, and when filled to the 4 inch depth hold roughly the same amount of media as a 3 gallon nursery container. The mesh bottom allows perfect drainage when kept on blocks, a shelf or otherwise off the ground. It would be reasonable to use either a nursery purposed blend for potting media - being primarily composted bark with some peat and other additives. Or use a bonsai specific media. Bonsai media tend to have significant inorganic materials like Pumice. Either way, I would use at least 25% to 50% minimum composted bark in your mix. This will hold water, an keep a mildly acidic reaction, which would allow you some "margin for error" on watering. A mix based on totally inert ingredients like pumice and DE and Turface, tend to dry out quickly. In Texas heat may need too frequent watering to be practical for maples. Maples do not tolerate getting "bone dry". So avoid conifer mixes for your tree. A nursery mix, which is mostly organic, may allow you to water as infrequently as once a week in cool weather.

Second thought: "Inverse taper" - this is an advanced topic. Those new to bonsai often panic at the thought. In a young tree just beginning its training as bonsai "inverse taper" is nothing to worry about. In a mature bonsai, that has many years of training into the tree, and is ready for exhibition, "inverse taper" is a major flaw. Some view it as a "Fatal Flaw" and those new to the hobby, that see these discussions of "inverse Taper" regarding an exhibition grade tree mistake this to mean they need to be in a panic over the issue from day one of a tree's training. For a young tree, inverse taper is a trivial problem. Good growth management practices will take care of it. No worries. If any part of your plan for a tree includes; "Increase the trunk diameter at least by a third of its current diameter" then you do not have to worry about inverse taper, there will be plenty of time and opportunity to "grow the tree out of inverse taper" by controlling were growth occurs.

Now, about your tree. The point you identify as where the first branch was "cut off" and a new leader was allowed to develop is an accurate description, but missed its purpose. The "new leader" was the scion wood of 'Shishigashira', the leader that was removed was the understock. This is a maple propagated by grafting. That abrupt change in diameter, is the graft union. In all honesty, a fairly nice one at that. The understock is genetically different than the scion. Probably just an ordinary green leaf Japanese maple. The portion where the branches currently are genetically is the cultivar 'Shishigashira', or "Lion's Mane" Japanese maple. It will have the fancy, crinkled leaves and the great autumn color. You do not want any branches to form below the graft union, as these will look quite different from the 'Shishigashira' portion of the tree.

Typically, grafted trees are viewed with mixed feelings as bonsai. For trees like Japanese white pines and cork bark Japanese black pines, grafting is the only way to obtain a desirable cultivar. In Japanese maples, some cultivars can be successfully rooted by air layers, and or cuttings, and some Japanese maples will resist any attempts to root cuttings and air layer attempts will fail. As a group they are inconsistent, with some rooting easily and some being complete failures. For this reason all commercial producers of maples use grafting. Only a bonsai orientated nursery will produce cutting grown Japanese maples. International Bonsai in Rochester NY and Evergreen Gardenwork

 

[Leo in N E Illinois]

continued:

Being a grafted plant is not automatically a disqualifier. Your graft seems fairly well done, in time, especially if you continue to add caliper to your trunk, it can fade to the point of being not overly obvious. Right now you have 4 branches coming off the scion at the same point. I would think about the style of tree you want, and then I would reduce the number of branches to no more than 3, two larger diameter and the smallest diameter, or I would reduce the number to two, or if you really want a taller upright tree, reduce to one branch, that would be the main trunk.

To my eye, maples are graceful, vase shaped or wine goblet shaped trees. I would keep the two branches that sweep upwards in a graceful arc, each to serve as main sub-trunks. Then further up the tree, have each sub trunk divide again, and so on. The style is the informal broom, where you move up the tree, the trunk branches to 2, then 4, then 8 then 16 and so on.

Some will suggest air layering above the graft union. This could be done. I believe 'Shishigashira' is one of the maple cultivars that responds slowly but consistently to air layering techniques. But the process will delay developing this tree as bonsai. It will take a year to get the air layer(s) to root, and at least 2 years of establishing the new trees on their own root systems before they will be ready to train as bonsai.

You could just plan on working on this plant, "graft and all", recognizing that you have a 50:50 chance that the graft union won't smooth out enough to meet "exhibition standards" over time. Most of us do this for our own enjoyment, I've seen plenty of nice bonsai with an obvious graft union under an otherwise nice tree. Its up to you. And air layering can be done at any time in the future. You don't have to do it immediately or even this decade. You have a 50% chance the graft union will become virtually invisible. I would take the bet on that.

So my plan would be to
1. find a suitable grow-out container, find it before growth resumes in spring.
2. when new buds start to swell, or when you see landscape trees starting to wake up - repot this to the grow out container. Trim off downward pointed roots. If the grow out container is less than 5 inches deep (Anderson Flat or similar) no need to use a tile or other hard surface to flatten the root system, you can just prune off all downward growing roots.
3. Once potted up, let the tree grow with abandon, no further bonsai training until late summer after a repot.

Read the many posts in the Maples sub-forum of Bonsai Nut.