Repotting Bonsai

Repotting bonsai trees is one of the most basic yet most nerve-wracking tasks for any bonsai grower, and even the most experienced of growers approach repotting with caution.

- Gary English

I have killed many trees through bad repotting techniques and I am not alone (at least that’s what I tell myself!). All bonsai trees need to be repotted at some point. They grow in relatively small pots, which means there is limited space for their roots to develop. This limited root space is the very aspect that creates a miniature tree, but eventually all the soil gets used up and the roots grow around the boundary of the pot. Once the plant has become pot-bound it needs to be repotted.

Slower-growing trees need repotting a bit less often, but fast-growing trees sometimes need to be repotted once a year, especially when they are young. Older trees may only need to be repotted every five years or so.

The single most important thing about repotting is timing. Most repotting should be done in early spring just as the trees are beginning to show their new leaves. During early spring plants will grow with enhanced vigour, which means they are able to overcome the stress of the repotting more easily. They will also have less foliage at that point and the plants can use their stored reserves to repair the root damage instead of using it to keep the leaves healthy.

1 Check your plants to see if they have become pot-bound by gently removing the entire tree from the pot with the root ball intact. If you see a large amount of roots around the edge of the root ball then it is likely that the plant needs repotting. This is very similar to removing a cake from a cake tin. Use a thin knife or flat blade to gently slice around the inside rim of the pot and gently loosen the entire root ball.