Shimpaku Health

Shimpaku Health

Tree health is always something we strive for here at Aichien.  We try to keep everything healthy and strong so that we can apply the many different techniques of Bonsai and have the tree respond well.  Sometimes trees will become unhealthy and leaving them alone might not solve the problem.  In those situations we have to proactively get the tree back to health or the tree will continue to weaken and potentially die.  In this post, I will share a trick we use to keep a purchased Shimpaku that has root problems from continuing to die back during the Fall and Winter months.  As you can see from the picture above, some of the foliage is turning brown and if we don’t take care of the tree, more foliage and branches will continue to die during the Winter months.

Water in the Soil

One of the important aspects of Bonsai is how wet the soil is and how it affect the tree.  Depending on the tree, it may like the soil wet all the time or prefer drier conditions.  Understanding the trees water needs play a big part on how well the tree will grow and respond to Bonsai work.  In this particular case, we’re focused on a small twisted Shimpaku Juniper.  Have you ever thought about how much water they need?  Do they need as much water as say, a Trident Maple?

For the most part, conifers tend to like more drier conditions and deciduous trees like more wet conditions during the growing seasons.  During the dormant season, most trees do not like too much water.  Sometimes our Bonsais get too much water during the Winter, it may cause some root rotting issues and the tree will not grow as well during the next growing season.  To keep our trees healthy we have to check water levels daily and adjust the watering schedule accordingly to what the trees likes.  Just by how you water the tree can either add or take years away from its development.  I asked Mr. Tanaka how long it takes to master watering and he said, “10 years for the average bonsai person, 5 years if you’re good.”  It sounds unbelievable at first but after watering the yard for the last 7 months now, I understand what he means.  In the future, I will be writing a post about watering and fertilizing so I’ll explain more then.

Temperature’s affect on roots

Temperature is an important factor in root growth.  For most trees, the soil usually needs to be at least 70-75 degrees Fahrenheit (21-24 Celsius) before the roots will start to grow.  When the roots are too cold, the tree slows down and if the roots are too hot, the tree slows down. That’s why during the Spring and Fall months where the weather tends to float around the 70-85 degrees Fahrenheit (21-29 degrees Celsius) range, trees start to grow and can pull a great amount of water from the soil.

What’s the problem with this tree?

Mr. Tanaka and I looked at this tree and believe the reason why the foliage is dying back is because the soil is too wet.  This small Shimpaku is currently in 100 percent soft akadama.  I took a lot of care not to over water the tree but we were both worried that during the cold wet Winter, the tree may stay wet for too long and cause further damage to the roots.  The goal now is to keep the tree on the drier side so that the roots will stop dying off and the tree can make it through the Winter.  If you notice that your tree is not drying out like other trees, the tree may be weak and problems might start to appear if you don’t let the roots dry out.  On this tree, we noticed that the tips were browning out and slowly browning to the stem.  This is a sign that the tree is either too wet or too dry. Since the soil has been wet all the time, we knew the roots were weak and the tree has slowed it’s intake of water.  Here is what I did to help keep the tree drier for the Winter.

Here’s another shot of the foliage browning out.  This tree has already lost a couple of small branches.

Here is a picture of the tree out of the pot.  The soil is pure akadama and currently dry.  I didn’t water this tree for two days and the soil at the middle and bottom of the root ball was still damp.  When I pulled the tree out of the pot, the soil on the sides just fell apart and there weren’t many roots.

I found a pot that was slightly larger and placed the rootball inside.  Other then the soil that fell off removing the tree from the previous pot, I did not cut the roots or remove any soil.  Since it’s November and the outside temperature is dropping quickly, doing a full repot on a sick tree can be dangerous.

I lightly tied the root ball into the pot.

Once I tied the tree into the pot, I sifted small to medium size hard akadama and filled the pot.  The soil mix used was basically 90 percent akadama and 10 percent pumice.

Wait a minute!

You’re probably all wondering why I would put 90 percent akadama into the soil when I was worried that the root ball was holding too much water?  If you actually did think that, then good for you!  You’re thinking!  If you didn’t think about that, don’t worry, you would have thought about it soon enough. ;o)

Why I used Akadama?

We all know that in a basic bonsai soil mix, akadama is the main ingredient that holds most of the water.  Other components such as river sand, lava and pumice holds little to no water.  You would think that if I wanted to keep the tree dry, I would put it in 100 percent pumice or lava?  The reason why I used Akadama (hard) is because it drains well and it keeps the root ball in a more balanced temperature zone.  Let’s break those two concepts down and make some sense of it.

Drains – since the hard Akadama doesn’t break down for at least two years of use, when the tree is watered, the water will drain right through the soil and out the bottom.  Since the rootball is more dense and compacted, the water is going to follow the path of least resistance and flow through the new good draining akadama.  The results being that the tree’s root ball will stay dry.

Temperature- akadama is not a solid piece of clay.  There are tiny little air bubbles inside the clay.  When akadama is heated, it tends to retain it’s average temperature for longer periods of time.  In this sense, we can keep the temp of the root ball more even instead of having it swing up and down dramatically depending on time of day.  If I were to put coarse river sand instead, once the outside temp drops, the root ball temperature will drop quickly.  The important part is to keep the overall temp of the root ball stable for as long as possible and avoiding temperature swings.

Another example

Say I was having this same problem but instead of Winter coming, it was Summer.  What soil would you put the sick tree in?  Coarse river sand or akadama?  During the Summer months, this technique is used also but the soil is switched to 100 percent coarse river sand instead.  Reason for the switch is that during the Summer, the days are really hot and the night temp only drops slightly. Using the coarse river sand will bring the root ball temp down to the optimum growing temp during the night and allow the roots to grow more.  If I were to use Akadama during the Summer, the root ball temp may stay too high for too long and not allow the tree more time to grow the much needed roots.

The future

Once Spring arrives, I will pull the tree out of the pot and do a real repot and clean out the compacted akadama in the core of the tree. That should help the tree grow very well and recover during the Spring.  In the Summer I plan to write another post about the tree in regards to picking a nice front and future design ideas.  The trunk is very twisty and there are so many possibilities to what this tree can look like in the future.

I hope this technique can help you all in the future in one way or another.  As always…

Thanks for reading

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24 thoughts on “Shimpaku Health

  1. David says:

    I feel like an apprentice! Damn, some good inside information. Thx for sharing Peter!
    I always enjoy your posts… They always give a smile on my face…

  2. Jeremiah Lee says:

    Thanks for this great post!

  3. Thanks for your very insightful information. Too often when we ask someone what is happening to a weak-looking tree the answer is, “Either too much water or not enough water.” This comment isn’t very helpful. On the other hand your comments are very helpful in understanding what may be causing the underlying problem and how we may best help our trees to survive. Thanks again for your efforts to share what you are learning with the rest of us.

    • Peter Tea says:

      You are very welcome Michael. There is so much information here and I’m trying to get as much of it as I can to share with the rest of the world. I love doing Bonsai and hope to see it grow and grow in the future. Thanks!

  4. Luc says:

    Hi there,
    I’ve just discovered your blog, and as a beginner in bonsai art, I find it truly wonderful. It’s a great insight into incredible bonsai care, and there is plenty for me to learn.
    It’s really great that you take time to share your quality knowledge and learning like that, I’m really grateful for it. Keep it up !

  5. Tim burke says:

    Thanks for the tip Peter, as always I’m envious and grateful at the same time. I do have a related question if you’ve got some extra trivia in your noodle: I’ve got a White pine that is browning from to much water, thereis one or two green needles only on many if not half of the buds. With winter approaching I fear for the life of the tree, I can regulate the water but if I have any more buds die I’ll end up with the shortest fattest bunjin you’ve ever seen. Does this sound like something an Emergency repotting or aki supplement situation? I do recognise without seeing the tree and roots your advise might be limited but any thing would help ease my mind. Thanks for all you do… Tim

    • Peter Tea says:

      Hi Tim,

      Sounds like the White pine is very weak. I would up pot it like I did the Shimpaku in the post. Also, after repotting the tree, I would suggest putting a block under one side of the pot so that the water will drain faster so the soil will stay drier. If you can, place the tree in an area where it will not be rained on. Allow the tree to get really dry before watering and continue to water in this fashion till Spring. Once Spring comes, repot the tree and get rid of some old soil. I would recommend not cutting any roots during the repot. Again, afterwards, good Sun and less water. Keep letting that tree dry out before watering.

      From the description though, it sounds like many of the branches are going to die. Don’t be discouraged though. Just cut the ones that are dead off and continue to care for the roots. Better to only have branches die then for the whole tree to die. Having said that, I’m not sure how far the damage is and there is always the possibility that the tree may die anyways, but at least you tried. I hope this helps you Tim and good luck with the tree.

  6. Tung Tran says:

    It’s so funny that every time you have a new post, I’ve had the same problems or same things that I’ve been working on my trees. I’ve learned every single word of yours and applied to my trees.
    Thanks again for your great posts, Peter.

    – Tung

  7. Mark Leija says:

    I’ve heard that you will not get good nebari if you don’t know how to water correctly either. That means that your soil mixture must be pretty spot on as well. Would you share some of your soil mixtures with us?

    What a fantastic blog. It’s exciting to read the information you put forward and even more exciting to use these techniques and watch them work my little trees. Keep ’em coming Peter!!


    • Peter Tea says:

      Hi Mark. Yes, soil mixes and how you water goes hand in hand. Depending on the mix you use, the watering requirements will change. If you want the nebari to grow, the soil in that area has to be in an optimum water level. Too much water and the roots won’t grow and too less and the roots won’t grow. Factor in the type of tree and that optimum water level changes again. Because of all these factors is why watering can be very technical. For the most part though, nebari tends to grow when that area is wet and not at all if it dries out too quickly. I plan to write a post about soils and watering in the near future and hopefully it will add more insight into the whole topic.

      The soil mix we use is here this:

      Healthy conifers- 70-80 percent akadama, 10 percent river sand, 10 percent pumice
      Slightly unhealthy conifers- 50 percent akadama, 25 percent river sand, 25 percent pumice
      Unhealthy conifers- 0-25 percent akadama and the rest river sand and pumice in equal parts

      For deciduous trees or trees that like more water, add about 10-20 percent more akadama to the conifer mixes.

      Good question and thanks for the comment Mark.

      • Mark Leija says:

        Tell you the truth, I’ve never tried Akadama before but I ain’t scared! What would the soil mix be for fruiting or flowering trees be? Thanks again Peter.

  8. Rusty says:

    Peter, thanks again for a great post. I would like you to comment on different types of Akadama. You are talking about hard Akadama above, but I have had some bad experiences with soft Akadama that did not drain well and turned into mush very quickly. Could you say more about it, please?

    • Peter Tea says:

      Hi Rusty. Here is some info about different akadamas. The hardness of akadama is determined by how hot it is baked. The higher the temp, the harder it is. The soft and hard both have their place in Bonsai. Trees that need better drainage liked the hard akadama. The soft akadama is used in a different manner. Trees that don’t like a lot of water such as White pines are normally put in soft akadama. Because the soft breaks down quickly and compacts the soil, it will actually start to block water from entering the rootball so the tree stays much drier and healthier. You should use the akadama that best suits your needs. Overall though, for the average bonsai hobbies, I would recommend the hard akadama over the soft because with the soft, you have to really control how you water the tree when you initially use it. I hope that answers your question. Thanks for the comment!

  9. Adam says:

    Yeah, I used to work for an interiorscape company, where I would go around and water all the indoor plants in office buildings. It was always frustrating because the plants would turn brown if they were too dry, and turn brown if they were too wet. But most of the plants survived my care…
    But about bonsai, I saw a little feature about Seiko-en on tv one summer over in Japan, and one of the apprentices there was responsible for all the watering. He said that he will only be allowed to water trees for the first two years of his apprenticeship, and won’t be allowed to work on trees at all! I thought that was pretty extreme. It scared me away from wanting to apprentice. But I guess it was just that one bonsai en that does it that way.

    • Peter Tea says:

      Hi Adam, it seems to be different in every nursery. Other nurseries won’t even let a first or second year apprentice water because it can affect the way the trees grow so much. I believe I lucked out because I’m getting a chance to do lots of things at Aichien fairly quickly. In my fourth day of apprenticeship, I was watering the yard. Later though, Mr. Tanaka did say that he was nervous when I watered. LOL! Thanks for the comment Adam

  10. Frank says:

    Are the trees left out for the winter or put in a cold frame? What’s the temp in winter there? Below freezing?
    You said that akadama holds temp longer so if it’s cold it stays cold longer and the same if it’s hot? So your using akadama so that the soil either stays cold or warmer longer? Would you want a sick tree’s roots to stay on the warm side in winter?
    Good article and I would of never figured out that there was much of a difference in temp for akadama , pumice or lava.

    See you soon at the show next week. Do you need any Cigars?

    • Peter Tea says:

      Hi Frank. The whole temp topic is new to me and can be somewhat complicated. When Mr. Tanaka talked to me about it, he said that it was more of a feeling for him then any real facts. I have noticed though that there are techniques here that are used but can’t really be explained. Explanation or not, the techniques still works so I’m going for that right now. Perhaps in the future I’ll try some experiment with the temps of each component and have some physical answers to the technique.

      For sure though, a sick tree should have warm roots because they are most comfortable and can actively grow and get stronger. Roots do like to grow in either extremes. Thanks for the comment Frank and see you next week! A cigar would be great! Thanks!

  11. Jim Gremel says:

    Thanks Peter, you are doing a fantastic job!

  12. Sandy Vee says:

    Interesting. I’ve “potted up” trees that I thought would not survive until the next repotting season. I didn’t pay as much attention to the soil as you did. I would just give it an inch or two of red lava around the root ball.

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