How not to fertilize…

Last year I wrote a post about fertilizing, Refine your fertilizing this year! I wanted to expand on that and offer a few more notes, since, after all, it’s a brand new year for dung related issues-

Right, just off to the east field to muck spread!

Blogging is really a bit assumption-ridden, because we make one simple statement as if it’s unconnected to a million variables. For example, when I say ‘fertilize’, I assume that we’re using a fertilizer that has all 6 macronutrients, Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg), and Sulfur (S), which, if I don’t say that, or some other variable you’re assuming and I’m not, we’re NOWHERE. And we are better if we’re somewhere. At least.

  • There are very few instances in bonsai, in early training or maintenance, where you don’t want a fertilizer with at least all 6 macronutrients. (i.e., without magnesium your tree can’t create chlorophyll, and without chlorophyll the idea that your plant can create food for itself is sort of unconnected to reality, and hence, bending a branch is cosmically silly-)

Ok, covered that variable.

A few fertilizing comments for this 2014 season:

  • Many problems we might see—burned leaves, browning needle tips, leaves that are too dark green, etc.—are very often basic care issues that have nothing to do with fertilizing. Just to take that last one, very dark green leaves is an indication a bonsai that is not getting enough sun.
  • There’s rarely a need to slam a tree with twice as much fertilizer as the directions suggest. More of enough is not better in the world of plant nutrition.
  • Normally, flowering trees are first fertilized after the flowering period. But this is another general statement. Some plants are nearly perpetual bloomers, like the quince I’ve talked about so much here, Chojubai, and those should be first fertilized when they are growing shoots in the spring even though they might still be flowering.
  • If we fertilize flowering accents randomly or broadcast, you may diminish the blooming of some. Fertilize them like your trees, when they finish blooming, not during.
  • If we fertilize an old tree too much—a pine with craggy, old bark for instance—it may shed that old bark and begin looking young. Many plants are perennials in ways we cannot be, for they can be restored to youth quite literally.
  • If we under-fertilize a young tree it will begin to look older than it is…for one thing, it will develop bark faster. But it may take much longer to achieve the other goals we seek in bonsai, too, like substantial trunks, etc.
  • Get your water and soil tested! Fertilizing will be different for different pH ranges. For example, recent research suggests that phosphorus (P) from bone meal is only available to plants in soils with a pH below 7.0. In fact, for most bonsai, if you can get close to 6.5 pH, most plant nutrition problems are greatly minimized.
  • Finally, fertilizing is much less important than optimizing the big ones: Sun and water. If we optimize the big ones, we won’t be turning to fertilizer as if it were a magic bullet. It isn’t one. It’s a distant second stage booster on our little rockets.

Are you yawning yet? Well, I know it’s not jazzy stuff. The world of bonsai has more exciting parts to it, and can get pretty romantic, too. Hybridizing with flowers, for instance, is a sure way to make at least a few people blush. But hopefully you’re yawning more interestedly now about fertilizing.

Fertilizing incredibly well is only for really cool people. Join the Smelly dorks! We’re a band of organic fertilizing rebels called the Secret Smelly Society, and we’re not growing very fast. Ironically.


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  1. phlkrg says:


    Very useful and interesting information as usual…many thanks.

    I do have a request though. Can you give us some advice on watering. It seems to be the one skill I still cannot master after 8 years…frustrating!

    Thanks again…

    Phil Krieg

    Fort Myers, Florida

  2. Cindy Rodkin says:

    Great post thanks Michael! x

  3. Mary Miller says:

    Small yawn, big smile, good info as always.

  4. Judy Fister says:

    Can always use good poop on bonsai….thanks!

  5. biervenskus says:

    Will you explain (perhaps in another post) about the blooming time and when to fertilize. I don’t understand. Also, in regards to chojubai, how does one maximize blooms. Thanks for the information on fertilizing. I didn’t yawn once.

    • crataegus says:

      Generally bonsai are fertilized after blooming. As for chojubai, it’s helpful to let the extensions grow and then harden off, usually in June, before cutting them. That will provide the tree with the energy needed to bloom. They like a strong fertilizing regimen without an imbalance in nitrogen, which will also help bloom, but if you’ve an old plant with bark on, then you want to keep fertilizing minimal or it might shed the old bark.

  6. endsurg says:

    So I take it that you’re not in the “Superfertilizing” camp. Walter Pall has been touting a fertilizing routine that is 60 times the normal and recommended strength. His rationale is: “look at how beautiful my trees are so I must be right”. I have a little anecdote about a bonsai forest and fertilization that may fit in here. I hated one particular little juniper forest. I intended to auction it off on some unsuspecting newly at our local club. However, I decided its true fate was to be part of a bonsai experiment. It had a twin that I liked. For four years, I intentionally never fertilized the disfavored juniper as opposed to the “usual” regimen for all my other trees. After three years, there was absolutely no difference in how it looked relative to the other trees. Granted, its growth was less but it looked as healthy. Finally, in a fit and rage after viewing yet another hyperbolic advertising, I poured and entire bottle of Superthrive into the pot of the forest. Each morning. I would look for either Godzilla like growth or sudden death. After a total of four years, the tree looked as healthy but slightly smaller (though,not statistically significant) than all my other trees and I auctioned it off. I saw it last year at a local meeting, at which it looked good. The owner found out it was mine and he asked me what fertilization regimen I used because the tree looked so healthy when he got it. I said, “the usual”.

    • crataegus says:

      I can’t comment on Walter’s fertilizing as I don’t know what he’s using. Some of the organics for instance are very mild and 60% more is not out of the ballpark. Especially for some goals.

      I do prefer organic cakes or pellets because it is so easy to control different fertilizing regimens. I do not think that broadcast, everything the same, type of fertilizing can adequately take all our trees needs and all our goals under one roof. So there I think the Japanese have it right.

      Hilarious story…thanks for sharing. Superthrive is essentially a brain tonic.

  7. Mary Miller says:

    Ah yes, Superthrive .. It is one of the two most argued subjects on my Bonsai Myths page. Using sea salt because the bonsai is a shoreline plant comes in second! Keep it up Michael.

  8. Dan Koefoed says:

    Oooo, Oooo. Pick me. I’m in the Secret Smelly Society!

  9. Tom Rodriguez says:

    Mr Hagedorn,

    Yes Iam yawning,not so much from boredom but from information overload.Question.Do you think the majority of the people that visit any Bonsai site or read any Bonsai book are new to the hobby? My answer to this question is yes. I am one of the many people new to the hobby. I can only speak for myself. There are too many variables in most approaches to bonsai. You may say well because there is many variables. I on the other hand like Walter Pall’s method. Much more straight forward and simplified . Walter says watering is not an art !! Thank God. It’s scary to think otherwise .
    I do appreciate the time and effort that it takes to put together a blog as comprehensive as yours. I guess what I am trying to convey is your broad brushing another’s approach when actually it is the better way to get started in this great hobby of Bonsai.
    In a nut shell, get some trees going with a simplified horticultural approach I.E.
    Water Pall’s regime then,start to learn about each trees special needs.

    • crataegus says:

      Oh dear. I certainly did not mean to broad brush anyone’s approach, I did not know that Walter says watering isn’t an art. I don’t read his blog, and I don’t expect he reads mine. He’s a busy guy.

      My comments on my blog are based on 30 years of growing bonsai. Bonsai seems to be like a lot of other things, people are saying vastly different things. Go into their backyards and they all have beautiful bonsai. I dance Argentine tango, and it’s the same thing, every teacher sounds like they’re contradicting each other. Go watch the teachers dance and they dance gorgeously, all of them.

      Choose a path and run with it! Too much really can be too much. But we each have an audience somewhere. Hopefully.

      Good luck and welcome to bonsai! It really is supposed to be fun. Sort of like dancing is…

  10. endsurg says:

    Tom, In response to your question about if its only beginners who reads a bonsai site is a resounding “no”. I have been in bonsai for many years and, as Mike observed. there is a multitude of recommendations. Many of these recommendations are contradictory and downright destructive. For example, pinching of Junipers. For years, pinching of junipers was the “de rigueur”. for their care. It now turns out that this technique has been slowly “killing” them. What is happening in American bonsai is that seven to 10 years ago, several Americans went to Japan to study with Japanese masters and learned technique “from the horses mouth”. All of the misinformation is now slowly being challenged. How else to find out about this except to read blogs and take courses from these people? Learning bonsai is a lifetime process.

  11. Rafal says:

    Hi Michael,

    I really like your blog and what you are doing. However C in macro nutrients is for COAL, not for Calcium 🙂

    All the Best!

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