Repotting Closeups 2023

A few photos with captions of our repotting adventures in 2023…


A partial soil replacement of a hemlock, with the beginning of a muck wall to hold the soil in. The wall was up to the top when finished. It’s easier to repot large clumps and forests on slabs while leaving them on the slab and just partially reworking the root mass. With this tree the front and the back received this treatment. The muck is the muck I’ve used since about 2015, 1 : 1 : 1 sphagnum moss, akadama fines, and cooked corn starch. It stiffens after application and the roots love it. Also water penetrates it better than traditional keto. This isn’t my recipe, I think someone in Hawaii came up with it.


A Shore Pine gets repotted. This old fella was collected on Vancouver Island by the great Peter Wilson. This was a Seasonal class. The purple duct tape on the floor was from a photography session, not an archeology site next to an ancient river (the crack in the concrete).


Japanese Maple being repotted. This tree has been in 50% akadama, 50% pumice for the last 15 years or so. This is the maple I’ve featured a few times on the blog with the secondary trunk created from an air-layered branch up above. 


Grafting roots on a Stewartia. Much of the fine root growth there is from the scions. We cut the tops off the scions last growing season. After some investigation we found all 8 grafts had taken. These were approach grafts. A channel was dug into the bare area on the base of the tree, then a 2-year old sapling was pinned into it. After 2 years they’d fused well. 


Old imported Japanese Hornbeam forest from Iseli nursery. This one had a lot of organic fertilizer over the years and we’re still removing the dark, fine soil that creates. Although I love organic cakes and use them when I can, we have animal / bird issues in my garden and I now use Osmocote for the most part—which makes for cleaner repotting. I’m not fully in love with it (rolls off mounds, must be counter-sunk) but there’s no top muck to remove, trees are strong, and flowering plants do well. Anyhow lovely old forest planting, whoever put this together had a fine eye. Tricky Hornbeam to grow in a pot, though, the Japanese. Korean is much stronger. 


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  1. David Dixon Johnson says:

    Does Osmocote come in a variety of chemical formulations ie. X:X:X? If so, which formulation do you use?

    • crataegus says:

      Hi David, I’ve been using Osmocote Plus, 15 : 9 : 12. It claims an 8-9 month release rate, though in warmer months it will be less than that.

  2. Ray says:

    Thanks Michael, it answers some repotting ( partial) on slabs. Always great to see repotting season and beautiful trees. Yes I am using osmocote plus also , works well


    Greetings Michael !
    I was hoping you could clarify what you meant about “cooked” corn starch… how is it cooked/processed to be useable for muck ?

    “The muck is the muck I’ve used since about 2015, 1 : 1 : 1 sphagnum moss, akadama fines, and cooked corn starch.”

    Thanks and I hope you are well.

  4. Reg says:

    Excellent post as usual. I also have the same question about how you prepare your cooked corn starch.

  5. Lorraine Herel says:

    Michael, thank you for describing the partial soil improvement. If it is possible to show a picture of the whole tree along side of the root work photo, I would have a better understanding of the work done. Very interesting grafting too!

  6. alexbraunton says:

    Hi Michael,

    Thank you for the great pictures. With regards to the maple, would you suggest that mlx of 50/50 akadama/pumice for younger maples in development?

    Thank you,

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