To successfully growing bonsai, you need a special soil, as the plant will grow in a limited space, where the usable space of the pot is very small. You can find soils labeled “special”, “universal”, “for bonsai”, etc. in stores. But at best these are only semifinished products.

Soil for bonsai should support:

• drainage of excess water (drainage possibilities)
• air circulation (roots need air)
• maintaining the required humidity level
• provide the plants with the necessary nutrients

Therefore, bonsai soil is composed of a mixture of several components with specific properties and functions.

Minerals

The most popular mineral components:

• Akadama. Japanese clay, retains moisture and creates good conditions for the development of the root system. It has drainage and aeration ability. Slowly degrades and must be replaced every 2–3 years (see here).
• Pumice. Hard volcanic rock also retains moisture and provides oxygen to the roots. It is long-lasting and practically indestructible. (see here).
• Lava. Volcanic rock, indispensable as drainage or soil aeration. Due to its porosity, it is a source of macro and microelements that promote the growth of the root system of plants (see here).
• Clay pebbles. Granules of burnt clay with a porous surface, capable of retaining moisture, reduces the risk of root rot. Useful as a drainage system.
• Kiryuzuna. One of the best ingredients for bonsai soils. Consists of volcanic sand and clay mined in Japan. Contains silicon, magnesium, iron, aluminum, calcium, titanium, carbon, and sodium. Does not decompose over time. (see here).
• Kanuma. Fired clay, produced in Japan. Good at retaining moisture while keeping water from stagnating. After watering, the light yellow granules darken, which allows you to assess the degree of moisture in the soil. (see here).

Examples of classic mineral mixtures for different bonsai trees:

For deciduous trees: Akadama : Kiryuzuna : pumice – 50 : 25 : 25
For conifers: Akadama : Kiryuzuna : pumice – 30 : 40 : 30
For acidophilous plants: Kanuma : pumice – 70 : 30
For young trees: Lava : Kiryuzuna : Akadama – 33 : 33 : 33
Optimum soil for all bonsai species: Kiryuzuna : Akadama – 50 : 50
For seedlings: Lava : Kiryuzuna : Kanuma : Akadama – 30 : 30 : 30 : 10.
Minimizes the risk of overwatering/drying out: Lava : Kiryuzuna : Kanuma – 20 : 40 : 40

Organics

Since minerals contain almost no nutrients, organic additives of 10-30% of the weight of the mineral mixture are introduced for plant feeding when compiling the soil. It should be borne in mind that organics contain numerous both useful and harmful microorganisms, so it is recommended to heat organic components before use.

The most common organic constituents are:

• biohumus derived from the activity of earthworms;
• coconut peat from coconut shells, (see here);
• top peat or sphagnum moss, (see here);
• leafy soil, compost from fallen leaves or needles;
• shredded pine bark, (see here);
• charcoal prevents the growth of bacteria and mold, (see here).

Fertilizer

In the limited amount of soil in a container, nutrients are quickly depleted and need to be replenished periodically.
Mineral fertilizer solutions work most quickly. They are used during the period of active growth in spring and summer, when trees need more nitrogen.
In order not to burn the roots, it is important to monitor the dosage and frequency of watering.

The convenience of granular fertilizers is that they dissolve with watering and are effective for a long time. The greater the tree's weight, the faster the soil dries out, and it requires watering more often, thus receiving more nutrients.

In the fall, reduced nitrogen and increased phosphorus and potassium are required.
In winter, the amount of fertilizer should be reduced to a minimum or completely eliminated.
The most suitable fertilizers for bonsai and their dosage (see here).
Preparing the soil for your bonsai is a significant step that determine the growth and health of your bonsai tree. By selecting the right ingredients and keeping the soil rich in nutrients, you can create the perfect growing conditions for your bonsai.
You can purchase or order the necessary soil ingredients or a ready-to-use soil mix from us (see here).