How to do a good repotting?

Repotting for a bonsai is very important. It serves to keep the rootlets to feed the tree and to remove the large secondary roots. This process contributes to the dwarfing of the tree.

The frequency of repotting depends on the species and the vigor of the trees. A young tree can be repotted every two (2) or three (3) years depending on its growth, but for older trees that are in the maintenance phase, repotting can be done every five (5) years and even more according to some Japanese masters.

It is very important to plan your work on your bonsai. In order not to stress your bonsai, you should normally do only one big operation on your tree during its growing season. Either you do a repotting, or you do big ligatures or a big bending.

Repotting is usually done during the spring period. The repotting period is extremely short. It can be from a few days to one or two weeks depending on the species. Repotting should be done before bud opening. In hardy areas where spring temperatures can drop below freezing, it is important to ensure that newly repotted trees do not freeze.

Here are examples of trees that have just finished their dormant periods and are ready to be repotted.

Photo courtesy of Mr. Brian Donnelly
and the Groupe Bonsai Quebec

For larches, this period is very short. It is recommended to repot your trees during the period when the buds start to swell and become beige in color until the first needles appear. Some professionals believe that this is the best time to ensure a good recovery.

For the next photo, this is the opening of the buds of a Chinese elm. The buds are just beginning to open and this is the start of the repotting period for many deciduous trees. This period can extend until the first leaves open.

For amateurs who keep their bonsai in a cold greenhouse between two (2) and five (5) degrees Celsius during the winter, the repotting period can be done from January to March, always before the complete bud opening.

Image par Clker-Free-Vector-Images et Patrick Schwarz de Pixabay

Here are a few steps to make it easier for you.

• Prepare the substrate and all the tools to do the repotting.

• Gently remove the tree from the pot
• Check the condition of the roots.
• With a chopstick, remove the old substrate starting from the sides.
• Cut off roots that are too long or too large.

Photo courtesy of Mr. Brian Donnelly
and the Groupe Bonsai Quebec

• Prepare the pot to receive the tree (grid, inking wire)

Photo courtesy of Mr. Brian Donnelly
and the Groupe Bonsai Quebec

• Add a layer of substrate in the bottom of the pot. Make a small mound under the tree in order to place the substrate correctly under the tree.
• Tie the tree in the pot with the anchor wires.
• Start placing the substrate in layers in the pot to ensure that it penetrates between the roots.
• Using a chopstick, make circular movements in the substrate in order to make the substrate penetrate between the roots to eliminate air holes.

Photo courtesy of Mr. Brian Donnelly
and the Groupe Bonsai Quebec

• Water the tree well after repotting.
• Check in the following days and weeks to ensure that the tree is recovering properly.

Photo courtesy of Mr. Brian Donnelly
and the Groupe Bonsai Quebec

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