Bizarre Weather and Bonsai

Wacky weather makes bonsai grumpy too. We’ve had, in the middle of the United States and in Europe, some of the oddest weather in years: Very cold springs in both places. These unusual weather patterns can result in seriously bummed out bonsai.

Even if you’ve only a few seasons of bonsai under your belt, it’s probably obvious that a bonsai is a very vulnerable plant. Because it lives in a pot, strange weather is a stronger version of strange to the tree. We might need to wait longer to bring our trees out of winter storage, which can result in tree weakness if they’ve been growing there for a while already. Pests and diseases can latch onto trees they normally would not have a chance with. Or, we can simply have hotter summers than normal which create other problems.


I remember very well my first year as an apprentice in Japan—it was 2004 and the summer was so hot it was is if the sun had snuggled in close for a festive few months. Well, the bonsai and the bonsai apprentices who tried to keep things moist didn’t care much for that. Nagano Prefecture simply baked in a record-breaking heat wave that lasted months. When a young carpenter fell off a roof dead of heat exhaustion, Suzuki came into work the next morning with a no-joke look on his face and handed out white shirts and wide brim hats. ‘Don’t die!’ he admonished us, as if we were planning differently.

The result of that hot summer in Japan was that many bonsai got weak. The year after we had branch loss here and there, and some rarely seen disease was present on some of the heat-stressed trees. To strengthen them, they were simply taken out of their pots and put into wooden boxes with pumice tucked around their root balls, and left that way for a few years. Some were famous trees. We hadn’t done anything wrong, but there was only so much we could control. And one thing that has come back to me again and again since then is that older, more refined bonsai will be hit hardest during weird weather years, and younger trees less so.

It’s so easy to wonder what we did, or did not do, to cause this or that problem. We seem culpable for everything—after all, a bonsai is in our care, isn’t it? Easy to take the blame, assuming we’re the only piece on the board that’s moving. But the weird year will make its own moves, and take its own casualties. And during those times we should expect some loss, hopefully not of whole trees, but perhaps an important branch will die. Do those things you can—Reposition trees. Put up that shade cloth you’ve been thinking of for hot spells. Plan in a third or fourth watering/misting on blazing days (preceded by retirement from work, naturally). Diagnose your diseases. Monitor cold periods carefully and don’t go by the calendar to bring them out of cold storage. And then, don’t wonder or beat ourselves up for what we’re doing wrong (which might be nothing) when our trees act weird during weird weather years.

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  1. bonsai eejit says:

    Reblogged this on Bonsai Eejit and commented:
    Excellent as usual, well worth a read.

  2. Karen VunKannon says:

    Nicely said, Michael, and much appreciated.

  3. Tony Tickle says:

    Reblogged this on Yamadori and Bonsai material from Tony Tickle and commented:
    good lessons to learn

  4. jkd2572 says:

    Full sun does not mean full sun in every climate. Here in Texas all my deciduous get 50% shade when temps reach 90 F. They can go to 108 F. I laugh every time I read that a trident maple loves full sun.

    • crataegus says:

      Very true! I used to live in Arizona and found the same utility in 50% shade cloth. It really keeps the ambient temperature down as low as possible, and yet also provides enough light for deciduous growth. I think conifer growth is limited with 50%, and 70% is even limiting to cuttings, but the setup you have sounds identical to what I used in a similar climate. Full sun can be nuts in many southwestern/central areas. In many of them we have what amounts to weird/severe weather every year—to a bonsai at least, if not to us.

  5. bonsology says:

    I have also been experiencing strange weather with substantial rain, severe storms, mudslides and flooding.

  6. Daniel Dolan says:


    You referred to 20% shade cloth…….is it your experience that this is the maximum amount of shading for a location that also has very hot summers [Chicago]. Or is it not a major consideration and anywhere from 20 to 50% is acceptable?

    PS Notice that I now limit my inquiries to simple questions rather than asking about ………” What is the best practice to follow for after care with Blue Atlas Cedars that have been recently approach grafted with Green Atlas Cedars?”

    I finally accept that there are limits to what one can fairly expect from a Bonsai Blog.[Your message to us from a few postings past.]

    Best regards,


    • crataegus says:

      Yes, and I think that part of the post is confusing enough that I will change it. It was just meant to be an example. Where I live I would not think of using more than 25% shadecloth, and have been doing well without using any. It’s cool springs that we have a problem with here. But everything I write here should be read with a grain of salt. Applicability is the key; still, I will try to be clearer and avoid specific comments that are easily misunderstood. (Maybe I should write under a penname to avoid damage to whatever credibility remains?)

      I think even 10% shadecloth has applicability, just to take the edge off of recently collected trees, those just repotted, etc. For Chicago I think about 35% would be about right for your hot summers for most plants, less for the pines. 50% should be used only in extremely hot areas like the southwest. And just for the hot summer months— shadecloth should not be used in the spring, fall or winter.

      Thanks for not asking about the cedars. I would have dodged that somehow, saying I know a nice gent named Jim Gremel who’s the expert there…

  7. Paul K says:

    Mike, thanks for the editorial on “problems” with our bonsai. It’s nice to know that masters have problems also. Although it would be a great presentation, I’ve never seen a professional stand before an audience and say, “let me show you some of my screw-ups and how you can avoid them.” Bonsai are difficult, yet we tend to blame ourselves for their demise. I tell everyone who asks about getting into the hobby that. It is not for the faint of heart and if someone can’t accept death of the things they love gracefully, bonsai is not for them. Murphy’s Law is always in effect. Anything and everything can happen. The other day, I was driving home from a session with a teacher. In the back open space was my favorite 50 year old azalea just styled to perfection. The uprighted back seat came loose from its fitting, fell backward and broke two of the major branches. It will take me five years to recover. What else can we do but sigh and hope the bonsai gods shine their light on us.

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