Every two to three years you have to repot the bonsai in new soil. The substrate then no longer offers sufficient nutrients and the pot is often no longer large enough for the root ball.

In a nutshell

  • The best time to repot bonsai trees is early spring
  • always use a special soil that is suitable for bonsai trees as a substrate
  • The size of the pot should be chosen to match the root ball and only be slightly larger
  • Root balls should always be trimmed when repotting
  • If the new substrate sags in the first few weeks after repotting, refill it

time

You can usually tell when it's time to repot the bonsai by the fact that the roots grow through the drainage holes in the pot. Depending on the tree species and pot size, this can be the case after just one year. You must repot each bonsai with new soil at least every three years. The substrate then no longer offers a good supply for the plants. In addition, the soil is usually heavily compacted, which means that the bonsai can no longer develop well.

Notice: Deciduous trees need to be repotted more frequently. You need a substrate change after three years at the latest and conifers have to be repotted at least every five years.

The best season for repotting is early spring. The ideal period is from around the end of February to mid-March. The bonsai trees are then in a resting phase and repotting does not cost them any unnecessary energy.

pot

A bonsai pot is used for a bonsai tree. A well cared for bonsai can often be planted in the same pot it was in before. The tray should always provide adequate space for the root ball after it has been pruned.

If you reuse the shell, you need to prepare it:

  • Roughly clean the bowl
  • Remove limescale
  • check for cracks and fissures

Notice: The pot size does not necessarily have to increase. If the root ball is pruned, the bonsai pot can also have a smaller size.

substrate

Bonsai trees need a special substrate. This must provide sufficient nutrients, but should still be permeable. There are special mixtures of soil for both deciduous trees and conifers that are suitable for repotting your bonsai.
Mixture for deciduous trees:

  • 25% pumice gravel
  • 50% Akadama
  • 25% lava granules

Mixture for conifers:

  • 33% pumice gravel
  • 33% Akadama
  • 33% lava granules

The soil for the bonsai tree should not contain any components that will decompose and thereby provide too many nutrients. Constituents in the substrate that are very fine are also problematic because they can help compact the soil. Most trees enter into a symbiosis with mycorrhza fungi. Therefore, always add a small amount of the old substrate to the mixture for conifers or deciduous trees. This inoculates the new substrate with mycorrhza fungi and the tree develops better.

Pot bonsai

To repot, you must remove the bonsai tree from the bowl. This can sometimes be time-consuming because the root ball is usually fixed with a wire. If the tree cannot be easily extinguished, it is better to cut the wire so that you do not damage the roots. Then remove the old substrate. If this is not easy to loosen, hold the root ball under water, the old soil is usually easier to remove. Pruning the root ball is essential.
A root pruning is necessary for the following reasons:

  • Space for new substrate
  • Formation of hair roots
  • Promote nutrient absorption

A bonsai does not need thick roots for stability, because it gets it by fixing it with wires. A fine root system is much more important so that it can be well supplied with nutrients. Therefore, you should preferably remove thick roots.

Pot bonsai

Once the bonsai has been prepared, you can repot it.

Instructions for potting:

  • fill in some substrate
  • Position the root ball in the middle
  • Fix root ball with wire through drainage hole or on wire holder
  • fill with substrate
  • Water the bonsai carefully

The wire for fixing the root ball does not disturb the trees. They usually remain permanently in the shell and are attached in such a way that they can no longer be seen once the substrate has been filled up.
When watering in the first few weeks, make sure that the substrate does not immediately float away. Preferably use a ball shower, with which you can distribute the water more evenly. Always water the saplings until the water runs out at the bottom and pour away excess water in a drip tray. In the first few weeks it can happen that the substrate sags again and again due to watering. Then refill with fresh substrate until it no longer settles.

frequently asked Questions

Should the bonsai be watered before repotting?

No, it is even better if you do not water the bonsai tree for several days before transplanting. This makes it easier to remove from the shell and you can simply shake off the old substrate.

Can I mix the substrate for the bonsai tree myself?

The individual components for the bonsai soil can be bought commercially or you can use ready-mixed substrates. However, always use suitable substrates for bonsai trees. Compost or forest soil is not suitable for bonsai trees as it would compact too quickly and is too nutrient-rich.

How do I know how many roots I need to remove?

You should be careful when cutting the roots. It is better to take away fewer roots and maybe repot next year. The remaining root system must still be able to supply the above-ground part with water and nutrients.

Category:

Garden plants