How to Care for a Bonsai Tree

In this tutorial we look at some basic tips on caring for your bonsai tree. This tutorial is for those who are new to bonsai and have recently acquired their first indoor bonsai tree.
peter chan with bonsai trees
It is inevitable that new bonsai owners will make a few mistakes, especially when they are so enthusiastic about their new bonsai. However, it is important for any bonsai owner, both experienced and new to stay well-informed and find out how to look after their bonsai tree from knowledgable, trustworthy sources.

In this tutorial, I want to go over some common misinformation on bonsai repotting.
Peter Chan Holding Bonsai Tree
I find that when people first buy a bonsai, they're so eager to start working on it that they can't keep their hands off it! Because of this, a common theme I notice with new bonsai owners is that the first thing they want to do when they get their bonsai home is repot. A common misunderstanding of new bonsai owners is that the tree needs to be repotted, however this is not the case. I have always said that a tree only needs to be repotted when needed. Another common misconception is that a tree needs to be repotted once the roots have started growing out of the pot. Again, this is not true. Bonsais are small by design and their root restriction keeps them this way.

When Should I repot my Bonsai Tree?

Bonsai repotting season is spring. Early spring is the best time to repot a bonsai.

A bonsai tree only needs to be repotted once it has become pot bound. For example, I have with me here a typical chinese elm. If we look at the roots, you can see they are quite close to the edge of the pot, but the soil and roots are still slightly soft, so I would not say it was pot bound. However, even if the tree was pot bound I would wait until the early spring to repot.
Bonsai soil
Spring is the optimum time to repot, when the tree is bursting with new life. I wouldn't reccomend you repot your bonsai at any other time of year as you risk killing your tree. If you have broken a bonsai pot however and the pot needs to be replaced, you can put the bonsai in a slightly bigger pot.

You can see this tree which I repotted during March still has the original root ball. I did not cut any of the roots. All I did was add some soil. This is fine to do outside of repotting season if the bonsai pot was broken or if you just want to put your bonsai in a bigger pot. Do not cut the roots outside of the repotting season, especially if you are a beginner.
Bonsai root ball
Here is another example. This is a Pistachia. As I take it out of the pot, we can see the roots have begun to spiral and sit close to the edge of their pot. This tree is not entirely pot bound, however even if it was, I would not choose to repot it during summer.
Pistachia Bonsai
This Japanese Holly is another example of a tree that is almost pot bound. Many beginners may look at this tree and think it needs repotting, but this bonsai will stay happily in its current pot for another two years or so.
Japanese Holly Bonsai

This Japanese Holly is another example of a tree that is almost pot bound. Many beginners may look at this tree and think it needs repotting, but this bonsai will stay happily in its current pot for another two years or so.
How do I Take Care of My Bonsai During Summer?

To care of your bonsai during summer (outside repotting season) all you need to do in regards to shaping and pruning is keep your bonsai trees trimmed.

Here is a pomegranate bonsai. You can see it has a few long shoots which need to be trimmed. However, I would advise any new bonsai owner to take when pruning. Pomegranate tree flowers are born on the tips of the shoots, so if you over-prune, you risk loosing your flowers.
pomegranate bonsai tree

pomegranate bonsai flowers
This Duranata is another example of a flowering tree where the flowers are born on the tips of the shoots.
duranata bonsai
Here I have a ficus. Ficuses are extremely vigorous trees, you will see shoots like this grow every couple of weeks. Take care to prune long shoots such as this.
ficus bonsai
When pruning your bonsai, you may notice insects or signs of insects such as this fluffy white residue we have on our ficus here. Insects are very active during spring and summer, but don't panic if you notice signs of them on your tree. A simple spray of insecticide should take care of this problem. If you don't want to use insecticide, you can use a jet of water instead. It is important to rid your tree of insects as they can suck the sap from the trees.
bonsai trees
The main takeaway I want new bonsai owners to have from this is that healthy and happy bonsais do not need to be repotted. Repotting outside of season can be detrimental to the health and life of your tree. The best analogy I can give would be to compare your tree to a healthy and fit person; it would be like cutting open their stomach just to see what was going on inside! There would be no need, and the person in turn would suffer unnecessarily.
Peter Chan in nursery
Good luck with your trees!