Hemlock Summer Trim-

Summer is a good time to trim a Hemlock. If we leave the spring shoots on a while, they build plant energy and grow roots. For a not-yet-developed bonsai, it’s a good idea to leave shoots on until fall.

On developed bonsai, mid-summer is a good time to trim shoots. If we cut too late, small buds won’t have time to develop size and energy before winter cold.  

I haven’t featured this Mountain Hemlock in a long time. It won the won “Finest Evergreen“ in the 2016 National Show. I collected it with Greg Brenden in Oregon fifteen years ago, and now every year there’s a two-day trim adventure. Which is what I wish to share today.


August 2022. Mountain Hemlock with spring shoots still unmolested. This is a big tree, 5’6” / 1.7m, taking 2-4 people to move (we use poles and straps underneath).


Both crowns are trimmed, the lower branches on left trunk yet to do. The spring shoots are 1/2”-2” long.


We have two options in shortening spring shoots. Option #1 shown here: Cut strong shoots back to smaller shoots. Option #1 thins foliage to make room for next year’s growth, and removes strong shoots.


Option #2, shoot-shortening: Trim back to buds. Hard to see the buds, but if you want length on the branch, to retain (part of the) stronger shoots, or to keep shoot density, this is your method of choice.

On this developed tree I used option #1 to thin most areas; option #2 on lower, weaker areas. In strong areas like the crowns I used a combination of both, cutting strong shoots off, then trimming back the remaining ones to inner buds.

Identify the buds carefully, as Hemlock won’t pop a bud where you cut.


After trimming. This tree is on display at the Portland Japanese Garden, should anyone be passing though. It’s in the hidden bonsai terrace up the stairs and through the main building. Ask for it! This terrace is supposed to be “discovered,” but I think giving a hint is allowed…

Here’s a post about the tree’s history, and its placement on the Corian slab base: Very Large Mountain Hemlock Clump

September 2022 Bulletin Board 

  • Book Signing at the Pacific Bonsai Expo! If you’ve not yet got your copy of Post-Dated (a memoir about my apprenticeship) or Bonsai Heresy (an offbeat educational guide to bonsai), visit my booth at the show. Buy a copy for a friend in desperate need of a bonsai book (we all have such deficient friends). I’ll be there both days, November 12-13, 2022 in Oakland, CA. Happy to chat bonsai, too! Bring your puzzlements, predicaments, triumphs. See some cool trees, chat bonsai, run home with books—what could be better?
  • Have September 24-25th free? Join us for the Seasonal-lite series! Our fall program caps the 2022 season, covering conifer and deciduous fall techniques, a deep dive into design  (including 4 traps to avoid), fine tuning your foliage pads, winter care, and much more. We’ve had folks from all over the world join us for these sessions (a few brave Australians have obliterated their early morning hours…definitely easier for our European participants.) For more info please look here, and to reserve a spot, send me an email at crataegusbonsai@gmail.com

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  1. Bill McKenna says:

    Hi Michael, you mention trimming back in summer to new buds in order to strengthen the remaining buds. Does that apply to spruce as well. It was my understanding that we should leave spruce alone until late fall. Thanks Michael

    • crataegus says:

      Hi Bill,
      Yes, spruce are usually worked on in the fall, through the winter. It’s a strong plant that might be benefited from working on later in the year to minimize bud size. Hemlock is…arguably, a tad weaker. And working on them a little earlier will fatten up the remaining buds so it’s strong in the spring. If we don’t leave the shoot long enough, like late summer, then we might weaken the hemlock, though. So there’s some of the thinking to do, to apply to the specimen you have in front of you. Ezo in Japan are generally worked on the fall. They don’t do much with hemlock.

  2. Jon Combs says:

    Hi Michael,

    I am a beginner at Bonsai. In fact, I’m not sure how strictly I want to know or follow the rules. I do however enjoy creating a “Japanese “ look to the trees and shrubs in my yard and have recently started trying a few potted bonsai.

    My question, which I hope you may answer, is this. How do you decide how much of the structure (trunks and limbs) to be seen? What is the method to achieve a balance between a pom pom look and a solid form?

    FYI: I live in Vancouver Washington and love Portland’s Japanese Garden!

    Thanks, Jon


    • crataegus says:

      A really interesting question Jon, how to prevent a Pom Pom / solid form look. For most conifers including hemlock, that means you’ll be cutting back to inner shoots that then develop taper for the branchlet. It also will thin the area, on a developed tree. Dense Pom poms are created when we nibble at growth. If all we do is nibble at the exterior, the branches will not have taper, and the exterior will get really dense. Crowding out light. And weakening and killing the interior shoots.
      Glad you enjoy the Portland Japanese Garden! Marvelous, peaceful place.

      • Jon says:

        That’s very helpful, thanks. I now have a clue as to how to better avoid Pom poms. What I really was asking was how do you decide how much trunk and branch structure to be visible? Bonsai styles seem to vary a lot in this regard. Is it personal preference? I do like to see the form and texture of the wood to some extent. FYI: just ordered your book!

      • crataegus says:

        Hope you enjoy the book! I think you’re right, it’s personal. Though how much structure to leave is usually related to how thick the trunk is. With a thin trunk, the pads can be smaller to leave more air; if a thick trunk, natural history would suggest more foliage grew that trunk, so large pads and less space—-and less visible trunk—-make sense. To me at any rate.

  3. One of my all-time favourite trees Michael! 🙂

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