Sciencing the Juniperus Communis yamadori riddle?

Now that is some lateral thinking! I might have to try that even if we settle on another procedure, just for the sheer cool factor.


So, doing some reading again, This seems like it could be potentially relevant, but I may be missing the point. Will try to find the whole article.

This seems to point to waterlogging as really detrimental to the plant’s capacity to fight off phytoptera.

I have also, without really knowing why - perhaps for future experiments in root disturrbance - taken some cuttings off of a number of wild JC with differing foliage characteristics in my local area. It is the wrong time of year, but hey, it might pan out.

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Hi all, in one video Ryan said that JC hate Akadama which one of the more frequent reason for its death after collection. I do not remember which video was it, but it is somewhere in the Mirai Live catalogue. Unfortunately, in that same occasion Ryan said nothing about the preferred soil. Maybe we should ask directly in a Q&A.


Hi simone! He mentions it in one of the BSOP streams i think. I wonder whether that’s really a thing with JC yamadori though, I think very few people chuck their yamadori into “proper” substrate until after a few seasons? Might be wrong about this of course.

I myself can’t afford Q&A access sadly, otherwise I absolutely would ask my JC questions there.

Bear with me if I ask Gustav, what does BSOP stand for?

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BSOP is the Bonsai Society of Portland.

Early on in Mirai Live’s history, Ryan did a series of streams at BSOP monthly for Mirai Live that are in the library. I forget which stream of that series he references communis though.

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Thanks nmhansen!

Ryan mentioned JC in the recent “Redwood revamp” stream, in essence saying that he suspects part of people’s trouble might be working it at the wrong time, namely early spring. He remarked that they need heat - so perhaps they are better worked in late spring or something like it. Still hoping for a JC stream.:slight_smile:

@nmhansen Nick, thanks. In the “Soils” video, which is BSOP (now I realise) Ryan is asked bluntly about the JC suggested mix. It is at minute 1h:09m but the question is asked together with a question on kanuma and Ryan forgets to answer the JC’s ones finally. Is this the video you were referring to?

I happened upon someone mentioning ryan’s suggested soil mix for JC, and it seems like pumice and lava rock, no (or almost no) akadama is the ticket.

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Hello everyone,
Steve and I have a handful collected here in WY. This won’t be true science in any regard, but here is some of what we’ve had success with.

The very earliest common that Steve collected went in to decomposed granite and did extremely well. When we potted it a few years ago it went into pumice and lava. That tree is still doing great

Everything since the first one has gone into straight pumice after collection. Steve has about 5-6 in his collection and I have a couple. One tree we named the “Comet” went to Todd Schlafer a couple of years ago. It grew like mad in the pumice. Todd posted photo’s after styling it last year. You should be able to find it on his social media accounts.

A decent one went to Owen Reich in Tennessee a few years ago. I have no idea if it survived the fire though.

A couple of keys that seem to make a big difference for us (also mentioned by others above):

  1. Keep shaded well after collection. This has been echoed by other professionals we’ve talked with.
  2. We’ve had good success collecting in warmer months. Though we have had success in regular collecting seasons as well. More experimentation is needed to figure out whether there’s a significant difference.
  3. We use pumice after collection.
  4. A good pad is an absolute must (ideally confined in rock that won’t allow long running roots to escape). At least with our experience and in our climate.

It would be awesome if any of you come up with science based info that will break the code on these. There are a lot of killer CJ’s out there!


I’ll also mention that Greg Brenden has a couple of great CJ’s that have been in Akadama mix soils for a very long time. I have a feeling there’s something else goin on there but unfortunately no scientific explanation.

A couple of other points that I just remembered. A few sources have noted that “deep” pots are important. Also, one professional suggested that they may be more susceptible to damage from late/early frosts, especially in a bonsai container. There are a couple of reasons I could see this as a possibility. 1) around here they tend to grow very close to the ground, and in areas that would remain buried under drifted snow well into spring. 2) we’ve had far better success sheltering them in cold frames than in our outdoor winter beds.


Hey Dan. Thank you very much for such a thorough post!

Substrate - The indications thus far are that CJs like substrates that limit the risk of overwatering, which tracks with one or two articles I’ve read that suggest waterlogged soil is pretty much the only thing wild in situ JC will not abide. Also, they seem fairly suceptible to phytophtera when too wet. This - to me at least - would explain why some people have success with akadama in their mix: they have better control over moisture levels (better at watering, drier climate or some such). The deeper pots would also make it less likely that any water stays standing in the pot, higher gravity column to overcome the clinging of water to the substrate.

The collecting them in warmer months sort of tracks with Ryan’s assertion that they need to be worked later in the year than other junipers, maybe. Might have to look into whether their metabolism/yearly growth cycle is “slow” in some way.

As for the whole frost thing, I’m not so sure. I live in sweden, and JCs here are subject to harsh cold during the wintertime. The nursery industry grow JC in small pots, and seem to give exactly 0 hecks about protection. I need to look into this - might totally be a thing, but perhaps in some more complex way. The late/early bit might indicate something there… not at all sure. The bonsai container changes things, as we know.

Sadly, there seems to be little to no research on root damage/disturbance and what is too much, or I can’t find the correct terminology for my searches. This is always a hurdle; the science scene is really jargony, and you may well find nothing at all with the wrong term. Same issue with the shading. Maybe something about root growth and what hormonal state direct sun drives.

Awesome posts, Dan. Thanks again!

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So, I’ve attempted to take a look at the changing pH-angle, and at least found some indications that acid precipitation seems to be a co-driver of some kind of nutrient imbalance in populations of wild JC (the study looked at seed fertility, foliage nutrient content), so there might just be something to that. Maybe collecting a tree from an “alkaline location” and plopping it in slightly acidic whatever is too much, too fast? Maybe a pH test of the field soil right after collection could be illuminating?

In case anyone was wondering about red lava…this cutting has been growing in it for two years now and is doing great.

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