Repotting a Kokufu Kaede

With repotting season in full swing, I thought I would give an overview of how I repot a tree using a Trident Maple (Kaede) that was once displayed at the Kokufu-ten.

The Trident Maple as it appeared in 1972 at the 46th Kokufu show. 1972 was the first time the album was printed in color.

The same tree as it appears today, 40 years after the first picture was taken.

The buds are swelling and have turned green, but the leaves have not yet emerged, perfect time to repot.

The first thing I do is make sure I have all the tools I need. The goal is to minimize the amount of time the tree is out of the pot, so having everything you need will allow you to work more efficiently.

In addition to tools, my soil is mixed and on standby. I will be using a 1:1 ratio of akadama and a porous aggregate.

I cut the anchor wires and wire clips that stick out of the drainage holes.

Next, I take a sickle and use long, smooth, shallow strokes along the length of the pot edge and slowly work my way down. I’ve found this more efficient than trying to get the blade all the way down into the soil and then yanking the tool toward you. Anything I can do to save energy helps me later, especially when repotting multiple trees during the day.

Once the tree is loose I lean the tree back and pull the pot down. This is an easy was to remove the tree from the pot. When handling the tree, never grab the trunk, this will damage and discolor the bark. Try to lift the tree by the root ball or at a strong branch junction .

The bonsai is going back into the same pot so I set the tree aside and prepare the pot. If you are changing pots, have the new pot ready before you start.

Its been two years since this tree was repotted and the roots have completely  filled the pot.

I use a root rake to comb out the roots and cut them back with scissors.

For larger roots I use root pruners.

I notice some older soil near the center of the root ball. As soil breaks down it needs to be replaced with new soil so that the roots stay healthy in that area of the root ball.

You can see the difference in the older core soil on the right and soil that was around the edges of the root ball on the left.

I’ve removed as much of the old soil that I feel comfortable with and have cut back some of the larger roots.

With the bottom done I comb out the sides of the root ball

There is a long root that emerges from the nebari and needs to be cut back.

Fortunately there is a better root underneath the long one that  I can cut back to allowing me to improve the nebari.

The root work is finished for now.The tree is tied to the pot using the 4 point tie down method.

The soil is worked into the roots with a chopstick and tamped down. Tamping the soil may seem like an unnecessary task, however it is important because it firms up the soil so that when you water the tree the soil doesn’t wash out. I begin at the trunk and work toward the rim of the pot keeping the tamper at a slight angle which pushes the soil against the pot wall. When I get to the edge of the pot I use my fingers to press down on the tamper and “set the edge” which results in a crisp, clean soil line.The last thing is to water the tree. Make sure to water the tree until the water coming out of the pot is clear, indicating that all the fine dust has been washed out of the pot.

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7 thoughts on “Repotting a Kokufu Kaede

  1. I am surprised that no organic additives are used in the soil mix. Is this standard for all trident maple bonsai?

    • From my understanding , akadama is used in place of organic soils, like pine bark, because akadama does not break down as fast as organic material. It also has additional benefits which could be the topic of another post.

      From an enthusiast’s stand point, akadama might not be a realistic option for people due to cost and availability. In that case organic based soils would work.

      • Personally I would love to see a discussion about soils in a future post. I’m relatively new to bonsai (only a year or so now) and soil seems to be one of the issues where there are a lot of opinions. I’ve heard from akadama/kunama purists who insist it is the best, also the fired clay/turface crowd that insists it is much easier to maintain and just as easy to use, also a few people who insist regular organic soil and frequent repotting is perfectly fine.

        Obviously a “final word” on the topic might prove difficult, but I would love to hear the opinions of the staff at the Arboretum!

      • Eric, I always tell our beginning students that in a room of ten bonsai people there will be 12 different best soil mixes. I tell them try what works best for the area (ask your local club) and modify as needed. The BEST soil mix is what works for you in your yard and watering habits.

  2. Pingback: Defoliating, Repotting & Other Tricks

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