Refine your fertilizing this year!

Nothing like a dogmatic title for good dramatics, right? I should add an ‘Or Else!’ but I don’t have the heart for it. Nevertheless, we should be duly chastised for broadcasting fertilizer as if it were an unmitigated good.


Whatever that guy is using should obviously be applied with discretion-

For bonsai, generally we don’t need axes to control growth. And for fertilizing bonsai, we can make this one basic distinction:

  • Begin fertilizing a young, unrefined tree when it begins growing early in the spring
  • Wait a bit with an older, refined tree—usually begin fertilizing when it’s just hardening off it’s spring growth

This makes two assumptions:

  • For the young tree, you wish to develop the trunk size and continue it’s youthful vigor…to fatten trunk, develop branching, get big joyful growth, have loud cellular parties
  • For the old tree, you wish to retain an ‘old tree’ feeling…to have thin twigs, small leaves/needles, short internodes, fine ramification, and pianissimo afternoon teas

To give some kind of perspective to this, at Shinji Suzuki’s garden in Japan where I studied, we started fertilizing around May 15. That was when the spring shoots were just finishing elongation. About 90% of the trees were attended to this way; the other 10% were fertilized later or earlier according to purpose. Here in my yard in Portland, Oregon, I’ve only got a handful of trees that are developed enough to follow the May 15 rule, so my percentages are reversed. I have mostly undeveloped trees, so I’m seeking more trunk size, branch creation, big leaves, and/or massive budding—so I fertilize most trees with the start of growth in March.

Ok. Quiz: If we were to fertilize everything the same, strongly, starting early in the year, what would happen?

  • The young trees would stay forever young
  • The old, developed trees would become young again

And here’s another one to nibble on:

  • The older the tree, the more important fall fertilizing is

(Disclaimer: There are plenty of exceptions to everything I just said, which naturally makes blogging about bonsai a total disaster. For example: Black pine, forget all about the old tree stuff. You want to fertilize the pants off even old trees in the spring if you’re cutting candles. And if you’ve actually got a pine with pants on, you’ve got bigger problems.)


  1. bonsai eejit says:

    Reblogged this on Bonsai Eejit and commented:
    Yet more words of wisdom from Mr Hagedorn. Excellent post and something that I have been trying to do for the last few years. The old wisdom of fertilization for all trees in Spring as new growth appears is utter tosh. I can already see a massive difference in my maples.

  2. Kelvin Rodrigues says:

    Excellent post, Michael! And done with suave, humour and intelligence too…

  3. terry davis says:

    Ryan has been telling us not to fertilize black pine until the needles stop growing, which is late August here. I think part of the key is to make sure they a late Fall dose.
    Lately I have been noticing minor element deficiencies even in trees fertilized with Miracle Gro, which is supposed to be complete. I am told kelp foliar is a good source of minor elements.

    • crataegus says:

      Follow your teacher. And be sure you’re getting all the information and not part of it. All paths diverge at some point, but the general fertilizing regime for black pines is to fertilize in the spring, then stop fertilizing when the candles are cut, then fertilize again in the fall. The details of how I do this, and how much, etc. are worthy of another post (which again is why blogging about bonsai is nuts, basically)—but again, if you’re studying with a good teacher like Ryan, follow what he tells you to do in all it’s details, because it is linked to other techniques—some of which might diverge from mine or anyone else’s.

  4. backcountrydan says:

    “The older the tree, the more important fall fertilizing is”

    Hey Michael, would you possibly be up for addressing fall fertilizing in an upcoming post? After your juniper progression of course! Our fall is fast approaching in WY, and I’d like to make sure I’m giving my older trees the right attention.

  5. Greg Wentzel says:

    PH is so important to fertilizing because trees will only absorb most nutrients when the PH is slightly acidic, about 6.5. Easy and cheap to check and correct.

  6. Philip Deschacht says:

    For pines ( japanese White pines) i also use Iron chelator once a year. My pines use to turn yellowish at the end of the winter , they stopped doing that. Pines need extra iron.

  1. […] a part of Michael’s latest post on his famous Crataegus Bonsai blog: “For fertilizing bonsai, we can make this one basic […]

  2. […] this point, I’d be well-served to borrow Michael Hagedorn’s disclaimer: “There are plenty of exceptions to everything I just said, which naturally makes […]

  3. […] this point, I’d be well-served to borrow Michael Hagedorn’s disclaimer: “There are plenty of exceptions to everything I just said, which naturally makes […]

  4. […] 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 […]

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