3 Important Points to Keep in Mind When Repotting
Repotting is an essential task in growing bonsai, and it can be said to be one of the true pleasures of the art.
I still clearly remember my master happily choosing pots and carefully considering the planting angle. Watching him work left a lasting impression on me.
With that in mind, I would like to share a few important points to keep in mind when repotting.
1. Deciding Whether Repotting Is Necessary
First, you need to determine whether repotting is actually required.
As a general guideline:
- Conifers (such as pine): once every 2–3 years
- Deciduous trees: once every 1–2 years
However, this will vary depending on the health and growth speed of the tree.
If you notice that the surface soil has become hard and water no longer drains well, this is a clear sign that it is time to repot.
2. Choosing the Right Timing
Next is the timing of repotting.
In general, the best time is in early spring, just as the tree begins to awaken from dormancy.
However, timing differs depending on the species:
- Plum and satsuki azalea: after flowering
- Azalea, juniper, and quince: during the rainy season
- Cherry trees and other rosaceae species: in autumn
Before repotting, always confirm the proper timing for your specific bonsai.
3. How to Loosen the Soil Properly
Finally, let’s look at how to handle the soil.
When repotting, the soil should be loosened according to the size of the new pot. However, if too much old soil remains, water will not reach the center of the root ball. This can lead to branch dieback.
Be sure to thoroughly remove any hardened surface soil.
In some cases, it may also be necessary to:
- Cut between the root spread
- Create small openings in the root mass
These steps help improve water flow and ensure the health of the tree.
Final Thoughts from Ogawa Sensei
Repotting is a process that places stress on the bonsai, and it has a significant impact on the tree’s overall health.
When you are just starting out, you may not know how much soil to loosen and may become overly cautious, which can make the process take longer. However, it is important to enjoy the work as you learn.
Even I was once too cautious, and my seniors would often scold me for it. Now, those moments have become fond memories.
About the Author
Ogawa Sensei is a bonsai craftsman trained under traditional Japanese masters. With years of hands-on experience, he shares practical knowledge and insights to help growers deepen their understanding and appreciation of bonsai.
You can watch how-to videos about repotting on our Youtube Channel.