Review of "Bonsai Heresy" by Michael Hagedorn

I want to enthusiastically recommend Michael Hagedorn’s new book, “Bonsai Heresy.” It is an absolute must-read, full of incredibly valuable, useful information for all bonsai practitioners.

Michael Hagedorn is one of America’s most experienced bonsai professionals, having trained for years with Boon Manakitivipart in America, then more years with Shinji Suzuki in Japan, and now maintaining his own bonsai garden in Portland. Hagedorn studied ceramic sculpture in university, and is the son of a scientist. He fuses these artistic and scientific influences in his bonsai craft, always exploring, pushing the boundaries of technique and aesthetics. And he does so always with a smile, and a wry sense of humor.

One of my earliest exposures to his approach to bonsai was while viewing the trees of the Artisans Cup. His vine maple really stood out from the crowd. It was “potted” in a custom-built structure made of nylon, packed around with sphagnum and various mosses, then wrapped in cheese cloth (through which the mosses eventually sprouted). In his audio critique of the tree, Walter Pall remarked, “The problem with this sort of tree… if you want to win an award, you don’t bring something like that. You must bring a powerful tree, nowadays. But it’s not all about winning awards. I love it.

Hagedorn’s Vine Maple (From the Artisans Cup)

Pall’s sentiment beautifully encapsulates Hagedorn’s approach, and the message he communicates in his new book, “Bonsai Heresy.” Tradition, and deep-seated preferences based upon tradition, dominate the bonsai world, and for good reason. Tradition gives us all a place to start; a broad understanding of what our forebears worked so hard to discover is a mandatory foundation for beginning one’s own bonsai journey. However, once this foundation is established, we need to be free to explore our own aesthetic sensibilities and push the existing bounds of technique. This is how art advances. From the book:

Though it can be liberating and fun to claim neophyte status, we in the West can no longer do so. We are well past the introduction stage in bonsai, that is decades gone, and maturity in any art means growing beyond beginnings.

I am relatively new to bonsai, having picked it up only in early 2020. But I was hooked from day one and it’s become clear to me this will be a life-long passion. I’ve already absorbed hundred of hours of Mirai streams, have read a half-dozen books cover-to-cover, and have begun my own little garden. For every video I watch or book I read, a handful of nebulous questions begin floating around in my mind, questions along the lines of:

  • Why do bonsai practitioners, even professionals, strongly disagree on the subject of akadama?

  • Is it okay to re-pot in the fall? Or should this only be done in spring? Is the answer species-dependent?

  • What do “too big” and “too small” mean with regards to pot choices? Aesthetic considerations aside what are the functional, horticultural consequences of using a very large or very small container?

After finding all the information in other bonsai “encyclopedias” to contain nearly-identical information from one to the next, every single chapter in “Bonsai Heresy” was eye-opening (some remarkably so)!

To touch on just one of the questions above - Hagedorn’s chapters discussing akadama were particularly illuminating for me. As a new bonsai practitioner, I’d found myself torn - Ryan Neil is a massive proponent of akadama, as is Boon Manakitivipart. They swear by its ability to promote ramification and scaling of healthy root systems. Yet I’ve also heard that akadama can break down into a dense, solid clay, potentially drowning/suffocating roots and killing plants. Hagedorn uses his experience to cut through all the confusion:

… As many of us are aware, when in a bonsai pot, akadama tends to break down… This is a common complaint about akadama, and the common conclusion is that because of this, it’s useless stuff and should be avoided. The first part of this sentence is correct, it does break down. The second part of that sentence is bollocks and completely misinterprets one of the main benefits of akadama… In a dense old broken-down akadama root ball, we see fine root growth. This translates to finer shoot growth…

… I hope every serious bonsai enthusiast gets a chance to at least see an old akadama root ball [in Japan]. After removing it from its pot, one of the most noticeable things is its density. In that interior core, if it’s been there a decade or more, the individual balls of akadama have completely broken down, and what’s left is a dense mass of uniform soil, assisted by the lung-like aeration of pumice or lava…

… Surprisingly, on closer inspection that entire dense core mass is also chock full of tiny feeder roots - healthy, growing feeder roots. And that might be shocking, as it was for me when I first saw it. For why would roots grow in something so dense? Yet they do… The eventual breakdown of akadama and the fine root growth it supports appears directly related to the fine ramification of a tree’s shoots. If you’ve ever been to a show in Japan or seen a Kokufu show book and wondered at the fine ramification that appears on bonsai everywhere, this is the reason. Fine roots in old root balls." (My emphasis.)

The entire book is full of similarly enlightening tidbits of bonsai wisdom.

“Bonsai Heresy” is split up into “Technical” and “Aesthetic” sections, with the former taking up the first two-thirds of the book, and the latter the final third. I personally found the “technical” chapters to be the most rewarding. After the points regarding akadama, another chapter I found fascinating discussed the idea that hardiness zones are not an end-all-be-all consideration in raising bonsai, as these zones refer to the hardiness of the top parts of trees, not the roots. In bonsai containers, our trees’ roots are exposed to far greater extremes of temperature than they’d ever experience underground, as non-bonsai trees. In this respect, we in the bonsai world need to be far more aware of the sensitivity of a particular species’ roots than someone just looking for some pretty backyard plants.

The aesthetic chapters were all worthwhile, but were uniform in their approach of encouraging the reader to, simply, question tradition. Why should we want to avoid bar branches? Are there situations where bar branches are acceptable, perhaps even desirable? What about pocket branches, pigeon breasts, and inverse taper? Hagedorn consistently hammers home the idea that, without thoughtful examination of these traditional bonsai “rules,” there can be no understanding, much less progress.

Alongside all this precious information are gorgeous, fun, vivid illustrations (Hagedorn chose the illustrator specifically to make images that break the mold of zen bonsai calm). And Hagedorn’s wit helps enliven the sometimes dense, technical chapters.

All told, this is hands-down the most valuable book I’ve encountered so far on my own bonsai journey. I give it my highest possible recommendation.


Re-reading old western books translated from Japanese (and being able to cross-check the original) was an eye-opening experience for me. What if I told you that the translators didn’t understand a thing about bonsai or horticulture, and the original authors didn’t understand a word of English. Does that sound like a recipe for disaster? It should.

The reason why the information is very similar across so many bonsai books, is that the information came from the same sources, which in turn received it from the badly translated Japanese books.

I’m going to take the “Master’s Book of Bonsai” as an example of badly translated Japanese books:
Akadama was translated to “red loam” (aka → red, tsuchi → soil), Kiryu to “sand-and-clay mixture”, Kanuma to “sandy light clay” and Kuroboku to “black loam”. Kuroboku is a non-issue as, as far as I know, you can’t find it outside Japan anyways.

I also think somehow juniper was translated to “oak” in the soil mixes for repotting… just like winter jasmine usually gets translated as “yellow plum”.

Soil for repotting
The standard combinations for repotting are outlined below.
For pine and oak trees, a combination of 70% red loam and 30% sand-clay mixture is desirable.
For other species a combination of 60% red loam, 30% black loam and 10% well rotted leaves is desirable.

Books between “Master’s book of bonsai” and now that recommend(ed) mixing loam/compost with sand most probably got the information from a source that referred to the “Master’s book of bonsai”.

The repotting frequency in the west is also something of a puzzler for me… Japanese instructions seem mostly to be “repot when the tree shows signs of needing it”. I believe the relative lack of refinement in western trees comes from repotting too often and therefore keeping the tree juvenile. The “fine roots in old root balls” would be the shin in Ryan’s videos.

For the aesthetic chapters… that’s another can of worms :slight_smile: I have found pictures of prize-winning trees at large Japanese exhibitions (Kokufu included) in the last decade showing bar branches, multiple branches from the same area, reverse tapering, crossing ramification, and all sort of similar “defects”. I think the “rules” aren’t “rules” but recommendations. A lot of the Japanese art forms play on the border between “in the recommendations” and “outside the recommendations”. I’ve tried having that discussion in my club, but the general reaction has literally been “that’s way above my comprehension level, so I’m going to pretend it doesn’t exist”.

Similarly, I think the “styles” are just templates to train your eyes/brain for proportions and movement and that tree can (and should) possibly integrate more than one style… this is one of the things Herve Dora does with a lot of his trees… they have a global outwards style but if you look closer, some sections are actually in a totally different style (several trees in a tree).

“Bonsai Heresy” will probably be added to my library soon :wink:


Oh man, TL;DR; (which is probably a sign that I shouldn’t even bother getting the book as I don’t particularly like reading). How would you say the ideas in the book line up with the “Mirai way”? I am interested in the book, but not if it’s going to just end up contradicting what I’m learning from Mirai. I’m all for some differing points of view to encourage some deeper thinking. I just don’t want to get another source of information that’s going to have me at complete odds with myself.


I’ve barely made it though the introduction of the book, but I’d be surprised if there is something outright contradictory. I’ve had the ability to hear Michael talk a few times, and read most of his blog and I would say it mostly lines up. Sometimes different terminology is used, and sometimes things maybe come from a different perspective, but I would say most of the concrete technical information lines up.


Michael’s approach is very much in line with Ryan’s. But the book presented some detailed technical knowledge that I’d never seen before, such as the root hardiness (as opposed to the general plant hardiness as indicated in the hardiness zone maps) of various species, which I found fascinating. He speaks in detail about various types of soils and which situations each is useful for. He dispels the myth regarding “leaf burning” from water droplets in intense sunlight. He also writes about twenty pages on watering, haha. From pH to hardness to watering schedule to any number of other details.

So I did learn a good deal from the book that I hadn’t yet learned from Mirai. But nothing contradictory.


Nice. I may pick it up and add to my stack of books I buy but don’t read. :weary:

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Serendipity… I found out that “Bonsai Heresy” was available semi-locally and it’s now in the post on its way to me. It wasn’t listed last week :wink:


So an educated experience bonsai professional has taken the time to write what works, and why mythology and commonly shared information is wrong. Michael explores the practice of fertilizing in a thoughtful way that explains why a shot gun fertilize em all the same is not a good practice. Some may be offended by the truth that working with old trees in containers is a finicky business, and one cannot just treat them all the same. He is a proponent of fish emulsion, but explains his experience of falling away from what he did in Japan, and a less than optimal result. Each chapter is worth reading, taking notes, and reading again. I highly recommend the book, and recommend following MH on his blog and website. :star_struck:

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Thanks for posting the review(s) of the Bonsai Heresy book. There was a discussion of the book on another forum and I had asked if anyone could list one “myth” that they had dispelled by the book…but people were treating the information like a document full of state secrets. So it is nice to have some tangible stuff being discussed here.

My experience suggests that a lot of the former Japanese apprentices (Michael, Ryan, Boon, Bjorn etc) have a fairly consistent and similar approach to the technical aspects of bonsai. Thus, I wouldn’t really expect much or anything Michael writes to be in direct conflict with what Ryan teaches. Differences are more likely to be between these guys (listed above) and local club experts who never went to Japan and have been doing things their way for 20, 30, 40 years. One example…there are still quite a few in the US who use turface-based soils, including some who’ve had trees in the National Exhibition, whereas all the Japanese trained professionals will stay a mile away from that stuff. Even though it obviously can work.

Think I’ll probably pick up a copy. Thanks again for the input.

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I agree that there seems to be a strong consensus among their technical approaches.

However, one very big difference between Ryan and Bjorn is that the former uses far more native American species, and is very much a champion of the development of an “American Bonsai” paradigm. Bjorn is invested deeply in the Japanese tradition and works mostly with typical species thereof. His studio also organizes annual trips to Japan (which I would love to participate in at some point!). I have found myself gravitate way more strongly towards Ryan’s project. Taking the centuries-old Eastern traditions of bonsai and adapting them to the American landscape has begun a very exciting movement!

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I bought a few trees from a grower at a bonsai expo last year. All were in a turface mix of some sort. Overall I was impressed with the root development, but I’ve had better development in 100% diatomaceous earth. As you said, Ryan doesn’t like the stuff. Says that it’s too greed with the water and won’t give it back to the tree.

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