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Potting Media
also known as. – “Soil”

 

One of the most widely debated subjects for most bonsai enthusiasts is soil composition. Ready-mixed soils can be bought from bonsai nurseries and garden centers but these tend to be relatively expensive. Faced with repotting more than 3 or 4 trees, most enthusiasts find a good source for a good bonsai mix or learn to mix their own soil.

There are a large number of soil ingredients that can be used when mixing your own soil. Different mixes are used by different enthusiasts with varying degrees of success. For the beginner, choosing which soil mix to use can be a difficult choice. You can only answer that question after experimenting over time with your own trees and care routines.
 

The Basic Requirements Of Bonsai Soils

Your bonsai tree is confined to a relatively small quantity of soil on which its very existence depends. Through the soil in the pot, the tree must be able to obtain water, nutrients and gases in order to grow. For this reason, your bonsai tree must be planted in a good quality bonsai soil.

The quality of the soil that is used directly affects the health and vigor of the tree. Unhealthy trees that lack vigor are very often planted in a poor soil mix. There are a number of qualities that are required in a good soil mix:

1 - Good water-retention. The soil needs to be able to hold and retain sufficient quantities of water to supply moisture to the bonsai between each watering.

2 - Good drainage. Excess water must be able to drain from the pot. Soils lacking good drainage are too water retentive, lack aeration and are liable to a build up of salts.

3 - Good aeration. The components used in a bonsai soil mix should be of sufficient size to allow gaps or air pockets between each particle. It is important to the health of the roots that they have access to oxygen.

A particle-based, well-structured inorganic soil allows fast drainage of water and allows fresh air to continually enter the soil. A compacted organic soil that lacks any structure also lacks aeration and drainage and this can lead to ill health in the roots and tree and root rot.


Varying Soil Mixtures To Suit Different Tree Species

Though all Bonsai trees require free-draining, water-retentive soils, different species vary in their requirements for water and nutrients and this should be reflected in their soil composition. Pines and Junipers for instance require less water than most other species; this in turn means that they require a less water retentive soil mix.

Alternatively, deciduous and flowering species have increased water requirements and tend to be planted in soil mixes with relatively high water retaining capacities.

When mixing your own soil, the ratio of water-retaining material to drainage materials is varied according to the tree that it is intended for. Very often grit is used to provide additional drainage to a bonsai soil.

By increasing the ratio of grit to the mix, the soil becomes increasingly free draining; by increasing the amount of water-retentive material, the greater its water-holding capacity becomes.
 

Organic or Inorganic Soils

Soil mixes are described as being either organic or inorganic.

Dead plant matter such as peat or leaf-litter or bark are described as being soil components.

Inorganic soil mixes contain little to no organic matter; instead, they are made up of specially formulated soils such as volcanic lava, grit, baked or fired clays.

These materials tend to be harder to locate than organic materials, but can be found in garden centers, bonsai nurseries, and in the case of some  fired clays, supermarkets and hardware stores.

Organic Soil Mixes and Components

Peat and other organic soil components have disadvantages; they can be too water retentive, leading to the soil being continually wet, particularly during periods of rain in Fall, Winter and Spring.

Conversely, during periods of high temperatures, dry peat can be difficult to thoroughly water, leaving dry spots inside the rootball of the bonsai tree.

Possibly the most serious problem with organic soils is that though they may consist of appropriate sized particles when the bonsai is first planted, they continue to break down in a bonsai pot and become compacted. As the soil compacts it becomes airless and drains poorly. Such waterlogged and airless soils soon suffocate the roots and can lead to rotting roots and ill health in a bonsai. This is why some trees need to be repotted yearly.

The only organic component that I would recommend used as part of any good bonsai soil mix is composted bark, sifted to remove any particles less than 2mm. While bark will break down slowly, it still holds its structure for a long time and until then, will not impede the air circulation or the drainage of the bonsai soil.
 

Inorganic Soil Mixes and Components

The advantage of inorganic materials is that they hold their open structure for a long time without breaking down into mush. Inorganic materials retain a certain quantity of water and any excess is immediately flushed through the bottom of the pot; it is difficult to 'over water' a bonsai tree planted in a good inorganic bonsai soil mix.

Akadama is Japanese baked clay, specifically produced for bonsai and imported into the West; it is normally only available from bonsai nurseries and therefore difficult to locate.

Akadama can break down into a solid mush within 1 or 2 years. This old soil must therefore be washed out of the roots every one to two years.
For this reason it is not recommended for species that will not tolerate regular bare-rooting (Pines for instance).

Turface / Oil-Dri / Cat Litter are fired clays and readily available. Compared to Akadama are much cheaper. Fired clays are also stronger than Akadama and thus will not break down over time.

As with Akadama, fired clays can be used on their own, mixed with grit for faster draining soil or mixed with 10%-20% bark if an organic component is required for greater water retention, while still retaining good drainage properties.

A wide number of fired clays are available; I would recommend contacting other enthusiasts in your vicinity for the names and availability of different baked and fired clays that you can source locally.

The Best Soil Mix for Bonsai

There is no single soil mix that is best for cultivating bonsai. Variables such as local climate and rainfall, personal watering regimes and individual tree species all contribute to variations in your soil mixes.

Ultimately, experience of using different soil types and ingredients will shape your own particular preferences. It is recommended that in the first
instance, find out the soil-mix that local enthusiasts are using and take it from there.i' bought from Nurseries and Garden

There are knowledgeable outlets selling good quality soil products, but these appear to be in the minority. Because you bought some ready-mixed bonsai soil from a nursery does not necessarily make it suitable for the health of your bonsai.

Similarily, if you have bought a bonsai tree from anywhere other than a well-respected specialist bonsai nursery that will care about the quality of the trees it is selling, do not assume that the tree is planted in a good soil.


Our Bonsai Potting Media

 
Organic Bonsai Potting Media
(white bag)

It is a custom blend of Peat Moss,
Perlite and Pine Bark.

$ 10.00 per bag