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Repotting a Japanese maple forest planting

January 22, 2021 by Jonas Dupuich

The Japanese maple below was created by Gene Lynch. It had been a while since it was repotted so I removed it from the pot to check out the roots.

Japanese maple

Japanese maple group planting

Jim Gremel pot

Jim Gremel pot

As expected, the roots formed a solid mat along the bottom of the pot.

Roots

Matted roots

My goal for the repotting was to reveal the trees’ surface roots and remove as much old soil as possible.

I started by removing the soil that had built up above the trees’ surface roots.

Soil covering the surface roots

Buried surface roots

Using a chopstick and bent-nose tweezers made it easy to remove the top half-inch of soil that covered the surface roots.

After removing the soil

After removing the upper layer of old soil

A nylon brush helped remove moss and stubborn soil clinging to the base of the trunks.

Brushing the trunk

Brushing the base of the trunks

After removing the broken down soil and cleaning the base of the trunks, a quick rinse removed the last traces of old soil.

After rinsing away old soil

After rinsing off the muddy soil

Once the top of the rootball was ready to go, I repeated the process on the bottom of the rootball. Here’s the tree after this work was complete.

Root work complete

Root work complete

I considered bare-rooting the tree but didn’t want to stress it too much so I left some of the old soil. I’ll plan to remove the remaining old soil in a subsequent repot.

From there I returned the tree in the same pot and applied a thin layer of shredded white sphagnum moss. The soil mix is roughly 65% akadama and 35% pumice.

Repotting complete

Repotting (and pruning) complete – 29″

I expect the tree to stay in this pot for another two-to-three years before it needs repotting again. During that time, I can start making improvements to the branches.

I can also think about whether or not to rearrange the trunks. I noticed that the rootball was flexible during repotting so it will be possible to make changes, if desired, the next time the tree is repotted.

New Podcast Episodes with Kaya Mooney and Carmen Leskoviansky

The Bonsai Wire Podcast recently featured interviews with Kaya Mooney, an apprentice at Kouka-en near Osaka, Japan, and Carmen Leskoviansky, caretaker of the bonsai collection at the Matthaei Botanical Gardens in Michigan. You can check out both episodes at bonsaiwirepodcast.com.

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Filed Under: Bonsai Development Tagged With: Japanese maple, Repotting

Previous Post: « Repotting a neglected atlas cedar
Next Post: Repotting satsuki azalea »

Reader Interactions

Comments

  1. Jim Stimmel says

    January 22, 2021 at 5:17 pm

    You did this in January, in California?

    • Jonas Dupuich says

      January 22, 2021 at 6:16 pm

      Hi Jim – Yes. I often start repotting in December and try to finish up in January as trees are already growing in my garden.

  2. Loi Le says

    January 22, 2021 at 5:33 pm

    What kind of root hormone did you use? Thanks.

    • Jonas Dupuich says

      January 22, 2021 at 6:16 pm

      Hi Loi – I didn’t use root hormone when I repotted the tree. I only use hormones when I take cuttings.

  3. Alessandro says

    January 23, 2021 at 1:27 am

    Nice job Jonas, as usual!
    It seems to me that in the leader tree on the left (and also in the second leader on the right) there is a lack of “conicity”… do you plan some works in this direction? How?
    Thank you for sharing your experiences!!!
    Alessandro

    • Jonas Dupuich says

      January 23, 2021 at 9:15 am

      Thanks, Alessandro! That’s right – the apex lacks taper which leaves two options: reduce the trunk and grow a new apex or make the tree taller by extending the apex with more slender growth. I expect I’ll grow new apices on both of these trees as the planting could be a few inches taller.

  4. Tony says

    January 24, 2021 at 1:52 pm

    Hi Jonas…..looks refreshed and ready to grow!….would you condie adding additional trees to the composition?….are there 12 trees in this group? Thanks

    • Jonas Dupuich says

      January 24, 2021 at 2:14 pm

      Thanks, Tony! Yes, I’d definitely consider adding or subtracting trees if I can find good matches. There are 12 now. I plan to rearrange things a bit the next time I repot.

      • Tony says

        January 24, 2021 at 3:41 pm

        cool!…..it is a very good composition so with your normal tweaking will be even better….as you know I have a weakness for forest plantings!…

  5. Joel Otteman says

    January 24, 2021 at 4:11 pm

    Beautiful composition

  6. Jesus says

    January 28, 2021 at 10:26 am

    Hi Jonas
    About the soil composition, 65% akadama is what you use for all/most deciduous? or just for maples?

    Also, is fired akadama (aka. super hard) a good component? or will it act as turface?

    • Jonas Dupuich says

      January 28, 2021 at 10:51 am

      Good questions Jesus! I use different mixes for deciduous bonsai ranging from 30-50% akadama at the low end to 80% akadama on the upper end. Tree health, stage of development, and species affect how much akadama I use.

      As for the fired akadama, I don’t have much experience with it so I can’t recommend or discourage its use. Fired akadama doesn’t behave like unfired akadama but I don’t know that it shares characteristics with Turface either.

      • Jesus says

        January 28, 2021 at 12:27 pm

        Thanks very much

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