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The Study Group


A reminder for new study group members and seasoned study group members.


The intended purpose of the study group is for us all to learn more about bonsai and take home skills that we can apply to our own trees.  I am here to help guide you (not do it for you) in the process of learning bonsai and exploring the possibilities.  You have a voice in the process too!  I will let you know my thoughts but I’d like to hear your thoughts and plans as well.  The only expectations I have of the participants is an open mind and an eagerness to learn.  Give me that and I will teach you everything I know!


All in all, at the end of the day, we should all be having FUN doing Bonsai.


Trees to Work On this Month

The following are things we can do with our Bonsai in January and February


  • Repotting (Just about all trees, tropicals are typically repotted in the Summer)

  • Ground/Air Layer (mostly on deciduous)

  • Styling of Conifers


For any one tree, plan on doing only ONE of the above techniques this Winter season.  More than one may be too stressful for the tree and cause a decline in health.


For those that are repotting, my recommend soil mixture are as follow:

Deciduous: 50% Akadama, 25% Pumice, 25% Lava

Conifer: 40% Akadama, 30% Pumice, 30% Lava


Be sure to sift all your soil to size so that you have a medium and small size mix.  Medium is used for larger trees and small soil for smaller trees.  Also, make sure to bring medium size pumice by itself to be used as a drainage layer if needed for your trees.

Key Concepts that affect the rate of growth in Bonsai:


  1. Sun

  2. Water

  3. Soil and Container Size

  4. Repotting Interval

  5. Fertilizer

  6. Cutting

Why Repot?


The reason we repot is to manipulate how the Bonsai grows. All techniques in Bonsai was developed to direct the growth of the tree so we can then turn them into Bonsai. Here are some reasons as to why I would repot a tree.

  1. The tree is in a mix that is too wet

  2. The tree is in a mix that is too dry

  3. The tree is so root bound that the health of the tree starts to decline

  4. To slow the growth of a tree (trees that are too strong)

  5. To accelerate the growth of a tree (trees that are weak)

  6. To develop the root spread and root system

  7. To get the tree into a mix that is manageable by the owner

  8. To change the planting angle of the tree

  9. To place in larger pot for tree health

Just like the other techniques we apply to our Bonsai, always consider the species and health of the tree and vary your degree of root pruning. As you’re repotting, you should also ask yourself these questions.


Did we continue the development of roots?

Did we get the tree in the ideal position?

Is the tree firmly tied to the pot?

Is the soil mix we’re using going to cause the tree to grow too fast or too slow?

Is there enough or too much room for the roots to grow?

Is this an appropriate pot for the tree?


When to Repot

The best time to repot in the bay area is December through February. Start with deciduous trees first then conifers. Once the trees have been repotted, make sure to protect them if there are sudden hard freezes during the Winter.


Repotting Interval


Developing: 2-3 years

Refinement: 1-2 years


Developing: 2-3 years

Refinement: 3-5 years


Broadleaf Evergreen

Developing: 2-3 years

Refinement: 1-2 years


Repotting Early vs. Later

Due to our mild Winters, it can make a difference repotting in December vs February.  It all comes down to how fast you want the Bonsai to grow.  Repotting in December generally yields a strong Spring push whereas repotting in February slows down the Spring push. The difference is not huge but can be enough to affect how refined trees continue to develop.


Soil Mixtures Peter Tea Uses


Fast growth mix: 33% Akadama, 33% Pumice, 33% Lava

Average growth mix: 40% Akadama, 30% Pumice, 30% Lava

Slow growth mix: 50% Akadama, 25% Pumice, 25% Lava



Fast growth mix: 33% Akadama, 33% Pumice, 33% Lava

Average growth mix: 50% Akadama, 25% Pumice, 25% Lava

Slow growth mix: 75 % Akadama, 12.5% Pumice, 12.5% Lava


Broadleaf Evergreens: 

Can use either Conifer mix or Deciduous mix. Dependent on species of plant material.

For those that purchased Clay King Red Bag or AOKI Premix Bag (contains 75-80 % Akadama) from me, here is how to mix it to attain the above recommended mixtures:

2 part Clay King to 1 part pumice = 53% Akadama

1 part Clay King to 1 part pumice = 40% Akadama

2 part AOKI to 3 part pumice = 32% Akadama mix


Soil Sizes and Container Sizes

Soil sizes can change how much water it holds. Smaller soil has more surface area in a given container and surface tension of water plays a larger roll.  Generally small trees uses smaller soil and larger trees uses medium size soil. When creating your soil mix, keep the sizes of the individual components as consistent as possible. Large particles have a tendency to work its way up towards the top and small soil tends to work it’s way down. Use a sifter to sift the soil to size and remove the dust.


The size of the container also plays a role in how much water is retained. Large containers have larger surface areas and tend to hold water longer. Very small containers don’t hold much water at all.  Think about the size of the container, the soil mixture you’re planning on using and make the adjustments needed to get just the right amount of water retention. 


Pros and Cons of Level Soil vs. Mounted Soil

Mounted Soil Surface

Pros: Makes the Bonsai look like its been growing in the container for a long time.  This helps add age to the Bonsai.

Cons: Soil tends to wash away when watering. Maintaining a healthy root spread is more difficult.


Level Soil Surface

Pros: Ideal of maximum root health and easier to water.

Cons: One element of showing age is not utilized


Repotting Steps:

Raw trees:

  1. Cut tie downs wires

  2. Use a root sickle to cut the sides of the container 

  3. Remove the tree out of the container

  4. Fine the root spread by raking the top soil

  5. Lay the tree on its side and rake the bottom of the soil ball

  6. Bring the tree upright and lightly rake the sides

  7. Bare root if the tree allows it.  If not, bare root a small section

  8. Prepare the container with screen and tie down wire

  9. Add drainage layer of soil if needed

  10. Add small amount of Bonsai soil into container

  11. Place tree on top of soil and slightly work the tree down into the soil

  12. Make required adjustments in side to side lean, front to back lean, offset and soil level.

  13. Add a small amount of Bonsai soil and work into roots

  14. Tie root mass down with tie down wires

  15. Add more soil and work into roots with chopstick.  Keep filling soil to the desired level

  16. Water the tree till the water runs out the bottom of the container.  Keep water till the water runs out clear.


Refined Bonsai:

Same as above except reverse steps 4 and steps 5


Tools and Materials for Repotting

Bonsai Container



Root scissors

Root hook

Root rake

Root cutter

Root sickle



Wire cutter

Small brush


Battery powered drill/driver

Battery powered reciprocating saw

**Be sure to bring a strong bag or container to take your old soil home with you.  This way, the host of the workshop doesn’t have to deal with disposing of so much soil.**

Styling Conifers and Broad Leaf Evergreens


Styling conifers and broad leaf evergreens is something else we can do this month if you’re already finished repotting your trees.  Be sure that the tree you’re planning on styling wasn’t recently repotted.  The tree should be firmly held in the pot and not move.


When learning to style a tree, there are a couple of prerequisites to have.


  1. Healthy tree

  2. Ability to properly apply aluminum and copper wire onto the tree


Once we understand these two concepts, we can then focus on how to cut, how to bend and style a tree.  Not having these two prerequisite will make it difficult to successfully develop a nice looking Bonsai.




I understand that wiring isn’t something that everyone likes to do.  It can be tricky, confusing and frustrating to learn.  It was tough for me to learn how to do it when I first started in Bonsai (almost spontaneously combusted) but with practice and patience, it came to me and now it’s much easier.


For those in the workshops that are not very good at wiring, I hope we can spend this year working together and getting better at it.  You will be amazed at how much better your trees will look when the wiring applied works for you instead of against you.


Remembering these few tips will go a long way:


  1. Apply the wire in a 35-40 degree angle spiral 

  2. If using copper, the copper size should be a third the size of the branch being bent

  3. If using aluminum, the wire should be as thick as the branch being bent.

  4. Always try to tie two branches together with one wire

  5. The pain will be over soon


During the workshop, we will talk more in detailed about different wiring techniques.

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