Vol#25 Advices For A Perfect Bonsai Replanting

Bonsai trees require careful attention, but understanding the correct care process can be challenging

First, consider the reasons for replanting and the optimal timing for your bonsai.

There are several reasons to replant your bonsai tree. For example, you may need to change the pot size if the roots outgrow the current one, or adjust the planting depth to improve water drainage. You may also want to try something new!

Regardless of the reason, it's important to follow the best process to avoid common mistakes.

For instance, replanting without changing all the soil can be problematic, especially if the topsoil remains untouched. This may prevent water from reaching the root system effectively. This often happens when you want to change the pot or adjust the planting angle. In such cases, only the sides and bottom of your bonsai's root system are loosened.

The essence of replanting is to establish a better watering system, remove clogged roots, and promote new root development, thereby enhancing water and air circulation for a balanced soil.

Bonsai that haven't been repotted in years generally require repotting. Older trees, for instance, tend to develop a large number of surface roots, which cause the topsoil to harden and impede water flow. Additionally, even regularly repotted bonsai can experience soil compaction due to the use of organic fertilizer. 

At first glance, after repotting without loosening the topsoil but only the soil around it, it may appear that water drainage has improved. However, the hardened topsoil acts like an umbrella, repelling water and preventing it from reaching the core of the root system. This can lead to a decline in the tree's health and, ultimately, the death of your bonsai.

Our goal is to ensure water efficiently reaches all the roots, right? Therefore, it's essential to remove the hardened black topsoil. Loosen it as much as possible until the brown layer of soil beneath the black one is visible.

However, removing all the compacted topsoil can be challenging, especially for old trees or those with complex root systems. In such cases, you can use a drill to create holes between the roots or outside the root system to allow water to penetrate fully."

Trees also need to breathe, so ensure the replanting allows air to reach the core of the tree.

A daily care routine for trees is crucial, along with regular repotting.

Until next time !

ReBonsai　Yusuke Ogawa

Learn more about bonsai with these articles: 

Vol#23 Bonsai Care in 2023, A Year in Review

Vol#24 Choosing the Right Fertilizer for Bonsai Growth