The Importance of Anchoring the Tree in the Pot

In books and journals you can often read about the importance of firmly anchoring the bonsai when repotting it. Usually there are no details about the specific method of doing this. In fact this step of work is often assumed to be familiar to the reader. However for a beginner it's not always easy to understand the importance of fastening the tree in the pot, so the following article will delve into this topic in somewhat more detail.



The Roots' Development

When repotting a bonsai or indeed any other plant, it needs to be anchored firmly in its pot so that the roots can develop without being disturbed by any movements, small as they might be. There are many purposes that the root ball fulfils. The roots should anchor the plant firmly in the soil in addition to providing supply of water and the nutrients contained in it. Once a plant is put into a pot, the roots start growing and cling to soil particles or the walls of the pot. Unlike animals, plants do not need to move in order to find their food. By developing a fine branching in the soil, the roots take up water and nutrients, but the most important nutrient which is glucose is produced by themselves. The plant must be anchored firmly in the soil so that the roots can develop without being disturbed.

Seeds Love Stability, Too

When sowing seeds, they are buried beneath the surface or covered with a layer of soil, not just put on the soil's surface. This prevents them from being disturbed in their development or becoming unstable by movements caused by wind or irrigation. The seeds do however move when the shoots start growing, and this can still expose the roots to air, which could affect the growing of the seedling or even damage it. This does happen in nature and is a factor of natural selection. When sowing out, one can however take special care and reduce the loss of seedlings. This is why seeds should always be covered with a layer of soil and watered carefully.

Plants Do Move

There is a wonderful movie called "The Living Desert" which documents the survival strategies of plants and animals in the desert. The most stunning sequences are those showing the movements of trees. In time-lapse you can watch the growth plants from morning to evening and during several days. These beings, seemingly immobile, go through major changes in shape and appearance by growing. The same happens beneath the soil, even if it is harder to observe. Given sufficient humidity and temperature, roots can grow surprisingly fast between the soil particles. But when these particles are moving of the plant itself is moved, the root tips stop growing. They need time and stable conditions to be able to take up their work again.

Working the Substrate into the Root Ball

When repotting plants, on step is particularly important, the one called "filling the spaces" by the Japanese. This means the  fastidious work of poking and swiveling a chopstick between the roots, tapping the pot's walls and pushing down the particles of the soil with a small spatula so that no air pockets can remain and all the free space is filled with soil. These methods are particularly important to fill the centre of the root ball and the area beneath the trunk properly with soil. Watering thoroughly after transplanting is another means of preventing such air pockets in the soil. By knowing the purpose of each of these steps, beginners can improve the quality of their work and achieve better results. If these steps are neglected, the soil won't have the desired stability and air pockets will remain in the soil that will slow down or impede the growth of the roots.

Tree and Pot Form a Unity

Air pockets make it easier for a tree to move when there is wind or the tree is touched. Consequently, the development of the roots will suffer or come to a halt. The anchoring of the tree should be so stable and tight that the pot and the tree form a single object. One should be able to pick up the tree at the trunk and lift it together with its pot. Whether this is done by aluminium wire, by cord or chopsticks, the most important thing is that the tree is anchored firmly in the pot. There is a variety of methods for this, depending on the size and age of the tree, the state of its nebari or root ball, its species or even the shape of the pot. Choosing the right method is just a matter of practice and experience.

Wiring the Tree in a Pot's Drainage Holes

This is the most common method, which consists of anchoring the tree with aluminium wire which is run through the meshes and drainage holes in the bottom of the pot. Since a few years you can also find pots that have large holes for drainage and additional small holes for attaching the wire.

Material Used for Anchoring

If a tree has few roots, which is often the case for trees dug from the wild (yamadori), you often need a more efficient system for anchoring consisting of bamboo chopsticks, pieces of wood, screws and steel wire. (Typically, copper wire is not used for anchoring since the copper oxide might impede the growth of the roots). For shohin bonsai and trees that can easily be anchored, aluminium wire is usually enough. But when you need to make substantial changes in the planting angle or put the plant into a position where the root ball is unstable, steel wire or another method that firmly connects the tree with the pot might be more suitable. This avoids possible damage to the roots by irrigation, strong wind or touching the branches of the tree.

The Difference Between Bonsai and Potted Plants

The main difference between a bonsai and an ordinary potted plant is the beauty of the shape and the harmony between the tree and its pot. Another indicator are the special feelings that a person will develop when regarding a bonsai that has been cultivated with dedication over several years, demonstrating the fascination and suggestive power of a mature tree.

Example for Anchoring a Young Plant

A piece of wire is cut off and shaped to two loops.

A piece of plastic-coated copper wire is attached to the wire holding the mesh.

The wire is threaded through the mesh and fixed at the hole in the bottom of the pot, bending the ends with pliers.

The ends of the wire are shaped into loops.

The pot prepared with the wire.

After repotting, the trunk sits firmly in the pot.


Using a Cord with a Single Drainage Hole

This method of anchoring started to become popular in Japan with the azalea boom around 30 years ago. It is a very efficient method to prevent the thin trunk of azaleas from moving after repotting. Bonsai lovers still use it for training pots today. The method is universally applicable and very consequential.

Three, the Perfect Number

Sometimes bonsai that should recover from a stress situation are potted into training pots of clay with three areas of support. These training pots have a ring at the bottom that has three gaps. This ensures that the training pot sits firmly on an even surface, the gaps ensure that excessive water can run off and they hold the cord in this method of anchoring.

The Improved Method with a Single Cord

The method most frequently used for anchoring uses several cords that are threaded through the drainage hole and crossed several times to stabilize the trunk in all directions. This method however is not very efficient, since the cords might become loose no matter how many of them are used. The drainage hole cannot be covered with a mesh, and the thickness of the cords will make the pot less stable. If one of the cords becomes loose inside the pot, the entire structure will fall apart, since the slightest loosening of the cords will put the stability of the tree into danger. The method presented here uses a single cord that is attached to the drainage gaps at the bottom of the pot instead of the drainage hole. If the cord is tightened around these, there is no danger of loosening. Once familiar with this method, it is easy and quick to perform.

The Method

Two of the openings or gaps in the pot's bottom rim are showing to the front and one to the rear. The end of the cord points to yourself (it should have a sufficient length). Now the cord is directed beneath the pot through the opening in the rear, upwards over the rim of the pot, passing the trunk on the right side and making a bend to the left. From there it goes to the left gap in the pot's bottom rim and under the pot to the right gap, up again and, passing the trunk on the back side, to the same left gap in the pot's bottom. From there it goes to the right the same way as before, up and this time on the left side of the tree to the rear. There it is joined with the other end that is brought to the rear too, across the other cords on the bottom of the pot, and both ends are knotted together. (See the illustrations below).

With this method you just need to make sure that the Tachiagari (the lower part of the trunk up to the first branch) is higher than the rim of the pot, so the plant shouldn't be potted too deeply.  A cord made of polypropylene is best suited for this method. The cord should not exert too much pressure and have a certain elasticity so that it doesn't cut into the trunk when it thickens after a while. After around six months when the tree sits firmly in the pot, the cord can be removed again.

The tree after anchoring it with a single cord.


This article was kindly provided by BONSAI ART.


Translation: Stefan Ulrich