How to Prune Bonsai Roots Without Killing The Tree

This article is the second part of my article titled Pruning in bonsai where I have discussed different types of pruning which are an essential part of bonsai tree care.

Roots are important to any plant and especially to a bonsai tree. It is the part of the plant which is not visible to the eyes in normal circumstances but plays the most important role in the plant’s survival.

So when it’s your turn to prune roots you should be very careful. I would try to explain the process of Root pruning by answering the following questions:

Why Should I Prune The Roots?

The basic purpose of root pruning is the same as that of branch pruning. As in the case of branch pruning (where small branches start to develop in place of regular-sized ones), Pruning of roots stimulates growths of smaller roots which are crucial for the look and survival of the plant.

Taproot is vital to the plants which grow in nature. It acts as an anchor for the plant. But in the case of bonsai trees, this root has very little importance. Here the support is provided from outside (Read wiring in bonsai for details).

Also, the presence of thick root inhibits the growth of any other smaller sized roots and thus lead to sparse branches with little foliage. So root pruning is absolutely necessary for the aesthetic look of the plant. It is an integral part of making the bonsai style.  

When To Do Root Pruning?

The frequency of pruning is not fixed for every plant. It varies upon the variety and species. Some plants grow very slowly and don’t need pruning that often whereas others need it quite a few times in a year as they grow vigorously.

The frequency is also related to the pot size and the environment. The smaller the pot more frequent is the pruning.  

When to Prune Bonsai Roots?

Before starting bonsai root pruning you should consider this. Pruning does hurt the water intake capabilities of the plant. So it must be done at a time when the stress on the plant is less; like during the period of quiescence (for tropical plants) or at the time of early spring.

The growth of roots doesn’t depend on light. Rather It is only dependent on soil temperature and supply of nutrients in the soil.  

How to Prune Bonsai Roots?

Once you understand the concept of root pruning the rest of the bonsai tree care will seem very easy to you.

First, you need to know about the equipment. For pruning bonsai roots, use a root hook. It is a single tined tool and is probably the best way to untangle the roots with minimal damage. If you don’t want to buy it you can prepare it at home too.

You need to let off most of the thick roots and concentrate on the smaller and hairy roots. These are essential for the plant’s survival. Bonsai trees have a very shallow root system compared to other container plants.

Sometimes, especially for a beginner, it seems impossible to shift the plant directly into a bonsai pot. This is okay. You can do it step by step. By lowering the depth of the pot over time. Start small and you will progress to severe pruning once you gain confidence.

Don’t get tempted to put water into the root ball to remove soil. It might work for some species but for most of them, it causes more damage to the finer roots than cleaning the soil. 

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