Why repotting a bonsai is particularly important.

The ideal repotting interval for deciduous trees is around two to four years, while intervals of five to ten years are ideal for conifers. With conifers in particular, repotting intervals of more than ten years can result in the root ball becoming so firmly entrenched that it can no longer be loosened by washing or scraping it out. This is the wrong way to go about it, as removing too much soil and root system can be fatal for the bonsai. If this is the case, only half the root ball should be worked on and loosened. The other half should be left untreated as a kind of safeguard. In this way, the treated half can regenerate, while the untreated side can absorb sufficient nutrients and water for the tree from the soil. After one to two years and when the tree has developed into a strong specimen, the second side can then also be worked on without hesitation. It is good for every bonsai if it is given a larger habitat with loose substrates (e.g. Akadama, pumice, zeolite or Kiryu) during this repotting phase. After a recovery phase of two to three years, the tree can then be planted back into a suitable pot without any problems.

During the bud formation period, it becomes obvious: our Scots pine is significantly weakened and produces correspondingly few buds.

The root ball of the tree has grown very dense and hard after not being repotted for over ten years. The lower root base is already pushing the entire root ball out of the tray.

Getting the tree out of the shell proves to be quite a difficult task.

The root ball that we see makes a healthy impression. However, the individual root strands clearly have too little living space. In addition, there are already many rotten root strands.

Now divide the root ball in two, as we only want to work on one half of the root ball, as described. To do this, we remove part of the root ball on one side with a saw, or with an axe if the roots are particularly thick.

We work the remaining root ball again intensively with a claw to loosen up the root system.

We now place the tree in a larger tray, which we first fill with a drainage layer (pumice, lava or pleton). We then add a new substrate. In this case, we use a mixture consisting of half Akadama and half zeolite.

This is how our finished bonsai looks from its new front side. Now it needs one to two years to recover.