The Japanese Maple Experiment

The Japanese Maple Experiment

Maple #1

Maple #2

Since it’s repotting season and I was itching for a maple side project, I asked Mr. Tanaka if I could develop these two Japanese Maples.  These Japanese Maples are called Arakawa Momiji which literally translate to Rough Bark Japanese Maple.  Unlike the typical Japanese Maple with smooth bark, these maples develop small and fairly hard bark plates.  Both of them have nice trunks and were field grown.  About 10 years ago, they were put into bonsai pots and sat at the overflow field that Mr. Tanaka owns.  A few weeks ago, I was watering the overflow field and stumbled upon these two and thought it was be great if I could practice developing them during my time here in Japan.  I showed them to Mr. Tanaka and he gave me the green-light to develop them during my own time (as if I had plenty of that… ;o)).

The first thing I decide to do was repot both of these trees.  As I was repotting the first tree, Mr. Tanaka glanced over and said that I should restart all the branches.  We both decided to repot both trees and during the Spring of 2013, I will cut off all the branches and force the tree to bud out at the cut branches and hopefully the trunk as well.  Mr. Tanaka then added that putting the trees in the ground would make them stronger then in a pot.  At that point, we both decided to repot one tree in a bonsai pot and the other tree in the ground as an experiment (for the blog).  I’m going to let both trees grow for the rest of the year and in the following Spring, cut off all the branches and see how both trees respond.  In this post, I’m going to show you what I did with each tree and continue to write more post about them in the future as they continue to develop.  Let’s get to work!

Arakawa Momiji #1

The current front.  I especially like the movement and taper of the trunk.

Here is the root ball after I removed it from the pot and cut some roots.  I will post the process of repotting in a future post.

Note on repotting:

Deciduous trees tend to grow slow after they are repotted.  The following year, if the tree isn’t repotted, it will grow even stronger.  There is a point though where the tree will become so root bound that it starts to slow down again.  Since this tree hasn’t been repotted in about 10 years, the tree itself, though healthy, is slow.  If the tree was repotted a couple of years ago, I could have bare rooted it with no problems.  Now that the tree is in a slow state, if I bare rooted it, I could potentially kill it.  I decided to go easy on the repot and keep more roots this time.  Next year when I repot again, I can be a bit more aggressive with the roots.

When you’re repotting your own trees at home, you should always evaluate the tree and put into consideration how strong it is to determine how aggressive you can get with the roots.

This isn’t the best picture but it does give you an idea of what the cork bark looks like.  The bark develops fairly quickly on this tree.  Branches that are about 4-5 years old will start to develop cork.

Here is the tree in a new wider pot.  I tilted the tree to the right a bit to show off more of the root spread (nebari) on the tree’s right.  I then put some sphagnum moss on the top soil to maintain the moisture level to help the tree recover from the repotting.  I set the tree in a nice sunny spot and will start to fertilize the the tree in the next couple of weeks.  The soil mix I used for this tree is 70 percent medium-hard akadama, 15 percent coarse River sand, 15 percent pumice with a splash of charcoal.  The granular sizes ranged from small to medium.  This is about the typical mix we use on our medium to large deciduous trees.

Rough Bark Japanese Maple (Arakawa Momiji) vs. Typical Green Leaf Japanese Maple (Yama Momiji)

Rough Bark Japanese Maple grow pretty much the same as a typical smooth bark green leaf Japanese Maple.  The new leaves come out green with a red border.  As the leafs mature, they will turn completely green.  They both are worked the same and feed the same during the growing season.

The benefits of using this type of maple is that the bark is very interesting and their wounds actually heal faster then a typical Japanese Maple.  Last year, I cut of a 1 inch (2.5cm) branch at the trunk and the wound as already callused over.  Other then the bark and healing speed, they are pretty much the same as a Green Leaf Japanese Maple.

Arakawa Momiji #2

This one is going into the ground.

 Since I plan on putting this tree in the ground, doesn’t mean I just pull it out of the pot and plop it into a hole in the ground.  I still have to do the root work just like a regular repotting.  This photo is a good example of finding the true root spread (nebari) before working on the rest of the root ball.  Normally, I would start on the bottom of the root ball first, but in this case I don’t know where the root spread is yet so I have to find it first.  If I don’t do this first I may end up taking too much from the bottom.  Now that I know where the root spread is, I can focus on the rest of the root ball.

Here is the root ball cut and cleaned up.

To The Field We Go!

In early March, Mr. Tanaka, Juan and myself made a small growing area at the overflow field (it’s not always sitting in a comfy chair in the workshop ;o).  This area is about 12 inches (30.5cm) deep with used bonsai soil (akadama, pumice, coarse river sand).  I took a shovel and dug about 8 inches (20cm) deep, leaving a slight hump in the center.

Next I placed a thick plastic bag on top of the hump.  This plastic will help force the roots to grow outwards as oppose to downwards.  Some people use a large tile or wood board instead.

Next I put a small amount of soil on top of the plastic.

Here’s the tree on top of the mount.

Next I filled the hole with soil and compressed it with with my foot.  I think you can see some of my foot prints in the soil! :op

Last thing I did was water the tree.

So all we can do now is wait and see how both trees will grow.  Which tree do you think will grow stronger and faster?  Most would say the the tree in the ground would and it is a very much proven fact.  The reason why I’m doing this experience is for couple of reasons.

1. Practice what I have learned in developing deciduous trees.

2. Trying to figure out if the gains of putting a tree in the ground as opposed to a pot, is worth the time in creating a growing ground in the future.

3. (Most important) I’ve always heard from my first year doing Bonsai till now that putting trees in the ground will make them grow faster and stronger.  One thing that has bothered me in Bonsai is that many people will always tell you how this and that works well, but they never did it themselves.  It’s always something they heard from other people and just accepted it to be true.  Once I came to Japan, some of those truths turned out to be incorrect and I thought to myself, “Wow! There is a lot of misinformation out there and I just assumed it was correct because that’s what people were saying over and over.”  With this experiment, I can at least say that I tried it and it worked… or maybe not work… we’ll see.  For you readers out there that haven’t tried it or can’t (let’s face it, we don’t all have large backyards), you can at least have some sort of visual evidence that it works or doesn’t.

The Fall

Both trees will continue to grow during the Spring and Summer.  In the Fall, they will both slow down and I’ll take some pictures of the new growth to see which grew faster.  I’ll keep you all updated with plenty of pictures.

I got more projects in the works so if you liked this post, there will be more coming soon!

Now you can say you were there at the beginning!  Thanks for reading everyone, and I mean it!

P.S. If you are actively reading this blog, I would appreciate it if you subscribe to it (right column of the blog).  This is one of the best ways for me to know how many people are reading.  Thanks!

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33 thoughts on “The Japanese Maple Experiment

  1. Edward Bodman says:

    Thanks so much for taking the time to share your knowledge and experiences with us.
    I have been looking for a blog/site like this for a while and am very excited as I also live in Nagoya!!
    If it were at all possible to come and meet you guys and look at your projects in person it would be great.

    • Peter Tea says:

      Hi Edward,

      That’s great that you are in Nagoya. You are more then welcome to come visit us. If you go to, the address will be there in English and Japanese. Just give us a call before so we can make sure we’ll be around when you visit. Thanks for reading the blog and take care

  2. Matt says:

    Hi Peter, I just wanted to say thank you for your no nonsense approach and the sharing of your experience. I have learned more from this blog, and the several others like it, than at my local club. I agree that there is alot of antiquated information out there and I have always enjoyed a bit of mythbusting. I love experimenting, which has at times led to massive failure. Thankfully on inexpensive material. I look forward to seeing the updates on all of your projects.

  3. […] of having two Trident Maples that are similar such as in my last post about the two Rough Bark Japanese Maples, I decided to change it up a bit and develop one root over rock.  If you’re not familiar […]

  4. CJ says:

    Hi Peter, congratulations on producing an educational and entertaining blog. I enjoy reading them.
    I am so glad that u have taken upon yourself the task of bonsai mythbuster. I agree with u that there are just too much myth in the bonsai world out there.
    However trees do grow faster in the ground than in pots. I have enough experiences to confirm that. After about 9 years, my corky bark oak trees planted in the ground has trunk diameter that is more than 10 time that of the same batch grown in pots. The same with my JBP.

    • Peter Tea says:

      Thanks for the comment CJ and thanks for reading the blog!

      I’m not so much as experimenting the fact that trees will grow faster in the ground. I’m experiment more on if a tree thats put in the grown for a year will be much stronger compared to a tree that’s put in a pot for a year. Though I don’t expect the tree in the ground to get much bigger in a years time, the results might be surprising. It sounded interesting and I thought it would be fun to share. I can’t wait till next year when I cut both of them and see which one responds better.

      Thanks again for the comment CJ and take care. :o)

  5. Penny Pawl says:

    Hi Peter, I am sorry I missed your trip home. I have grown many trees in the ground to increase their trunk size. Also I annually shovel pruned the roots, other wise they go out too widely


  6. Paul Wycoff says:

    Hi Peter ! As always your post is very enjoyable and full of good lessons. It will be interesting to see the results of your experiments.
    Paul Wycoff, Santa Rosa, CA

  7. BVino says:

    Hi Peter, as you’re talking about differences between arakawa and regular Japanese maple, I wanted to share two observations and see if anyone else has noticed or if I should just chalk this up to the characteristics of the particular trees I’ve been working on. I find the branches of my arakawa to be much more brittle than regular Japanese maple and therefore much harder change the angle of or give movement to an already somewhat mature branch. The other thing I’ve noticed is that shoots on arakawa are more likely to weaken or die off when wired. I know this comment makes it sound like I’m killing all the branches on my arakawas! But have you ever noticed these differences, Peter?

  8. Very good info and photos Peter. I look forward to the progress.

    Have you any experience with air layers on Arakawa maples?


  9. Peter Tea says:

    My mistake everybody! Arakawa momiji actually means, “Rough Bark Japanese Maple.” Mr. Tanaka told me this and for some reason I wrote Cork Bark. Also thanks to Bill V for pointing that out as well.

  10. dyamins says:

    Peter — if next year when you cut off branches you find that the tree doesnt bud back on the trunk, will you consider grafting?

  11. snady789 says:

    Hi Peter,

    Great post. I’m looking forward to seeing all the progression photos. Being fairly new to bonsai, I am still a little apprehensive to chop off my maples to achieve those great ramifications. I read everything I can find but your posts are so much more informative. Thanks again

  12. George Haas says:

    Great post, Peter. I’ll follow the experiment with great interest. The post generated some great comments.

  13. marcuswatts100 says:

    Hi Peter,
    I think the one year experiment will give fairly equal results, the potted tree may even get stronger as it will recieve water and fertiliser exactly as needed. I imagine both will bud well after the branches are cut off – the potted tree will be stronger though as its roots are undisturbed in 2013. I think the better bonsai with finer growth will come from the potted tree, while fields are good for fast increases in size and rescuing very weak trees.

  14. Richard Green says:

    I love your experiment here. I’m a big believer in having a ground growing recovery area available. My guess is that both will do well for what you are needing. It would also be interesting if you made measurements to see if there’ll be differences in the thickness of their lower trunks.

  15. Jim says:

    Thanks again for doing this, Peter.

    I don’t expect that we will find any benefit to planting in the ground for just one year. Brent Walston of Evergreen Gardenworks has several articles on this topic. My experience is limited and non-scientific but does fit with Brent’s advisement:

    “in the long run planting in the ground is the best solution, but only if you plan to leave your trees undisturbed for three or more years, otherwise it will be slower than container growing.”

  16. Reblogged this on futterwithtrees and commented:
    The Japanese maple Experiment. Another excellant post from Peter Tea

  17. Once again another excellent helpful post. Thanks.

  18. Jim Gremel says:

    Thanks Peter. Great post!

  19. Sandy Vee says:

    Nothing like a slow paced adventure! In this case curiosity would sever better than impatience. Are there the same problems of delicacy with a corking maple like a corking elm or pine?

  20. […] link: The Japanese Maple Experiment « Peter Tea Bonsai comments: Closed tags: aichi-en, apprentice, bonsai, both-decided, ground, japan-home, […]

  21. Michael Markoff says:

    Nice article, Peter. I believe more experiments need to be done to further bonsai horticulture and debunk some long-held but flawed myths. In the interest of objectivity, would you measure the diameters and internode lengths (and any other parameters you think valuable) in order to make your findings more objective?

    • Peter Tea says:

      I’m planning on taking photos of both trees after the growing season and record observations that I see in the trees. One of them will definitely be internode lengths of the new branches. I’ll take leaf size into consideration as well. I believe a lot will be learned from just observing how the tree grows during the year and how much by the end of the year. I’ll check up on both trees from time to time and if there is something interesting to share, I’ll be sure to post about it.
      Thanks Michael!

  22. tmmason10 says:

    Peter, great post! Looking forward to the experiments results as I am trying to think of a growing ground as well. Did you end up cutting branches off? Is it truly growing in thr ground or is it more of a raised garden bed?

    • Peter Tea says:

      Hi Tom,

      Good question! I should have mentioned that I didn’t cut any branches off on either tree. I’m going to let everything blow out this year and do the cutting next Spring. The ground is more of a garden bed, but the soil underneath is very sandy as well and I have no doubts that the roots will grow below the bed. Perhaps when I end up pulling the tree out next Spring, I can dig around the root ball and take some shots of where the roots ended up going.

      Thanks Tom and take care!

  23. Fabrice says:

    Hi Peter and thanks again for this blog.
    I saw in general that the first year in the ground was not fantastic growing because the root system need to heal. Will you do your experiment on 2 years or just only one ?

    • Peter Tea says:

      Thanks for the comment Fabrice.

      Mr. Tanaka believe that one year is enough for what we’re trying to do. I do believe that if we leave it for two years, the tree would be even more vigorous though. It’s just a matter of do we need it that much stronger? As the tree grows this year, I’ll monitor how well they grow and share the results with everybody. Perhaps if the trees grow slow this year, I may have to leave it in the ground for a second year. Time will tell and I’ll keep everyone posted. Take care Fabrice!

  24. Jeff Q says:

    Just bought my first Awakawa a few weeks ago and I’m looking forward to reading how these trees develop. Thanks for taking the time to put what you are learing in writing so that we can still continue to learn from you Peter.

  25. Daniel Dolan says:

    Dear Peter:

    2 Questions if I may.

    1] You mentioned that the Arakawa Maple was…..healthy but slow. How do you know a tree is slow. As I understand you recently discovered this tree in the field and have not had the opportunity to observe it for any length of time presumably, what does the tree show that idicates it is slow?

    2] In connection with your use of a plastic bag to inhibit downward growing roots……..doesn’t this have the possibility of ponding water and damaging the roots?

    Just a comment about the “tribal knowledge” of bonsai practitioners….I was often told that placing snow on top of your outdoor wintered hardy trees would keep them at 30 degrees when the outside air is -10 F. Fewer people are aware of the 2nd Law of Thermodynamics and that if the ambient temperature is -10F…….your Bonsai is -10F. And in outer space, no amount of snow will prevent them from reaching -455 F.

    Thanks for all your posts and great photos.

    • Peter Tea says:

      Hi Daniel,

      Thanks for sharing your snow story. I got a good laugh from the space reference. LOL. Here’s the answer to your question.

      1. I know the tree is slow because it’s been root bound for 10 years. Deciduous trees that haven’t been repotted for that long a time in such a small pot is never strong. Also, if the tree was stronger, it would have so much more long and thick growth on it. I know the tree hasn’t been cut, at least for the last year I’ve been here because I’ve yet to see Mr. Tanaka cut any tree at the overflow area. I also did notice that there were several dead twigs here and there. I have a feeling the tree grew, then died back, then grew again and died back a few times, which would explain it not being very leggy.

      2. That’s why I had the built up hump in the center of the dug out hole. This will force the water to drain to the outside of the plastic and into the rest of the field.

      Thanks for the comments as usual Daniel and great questions! Take care.

    • Peter Tea says:

      Hi Daniel,

      I looked at the picture of the plastic bag again and I see why you asked about the pooling. The photo kind of gives it an illusion of the outside edge of the bag being level with the rootball. It is in fact much lower. There might be some slight pooling, but once the tree roots start growing, I have a feeling, the tree will suck that water up in no time. We’ll see what happens when I dig the tree up next year. ;o) Thanks again

  26. Christopher Denker says:

    Great work. I’m not a commenter (but a major reader), but imagine you appreciate knowing how many folks read your blog. Anyhow, fun stuff, and cool you’re able to run experiments such as this. It will be interesting to see how it runs out.

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