We show which soil is best suited for bonsai and why normal substrate is not an option. After all, the small tree has special requirements.
Bonsai grow in a small pot that has a big job. With its rather sparse content, it must provide the basis of life for the tree. Because the plants draw their water and nutrients from the soil in the bowl and find support. Not that less soil requires less labor or accuracy. Quite the contrary - due to the small volume of soil there is hardly any room for mistakes. This is not only reflected in the care of the miniature trees, but also in the choice of the right substrate for your bonsai.
This should be considered before buying bonsai soil
Without the right choice of soil, you will have little success in keeping your bonsai healthy for years to come. Bonsai soil should have certain properties: the irrigation water must drain well to avoid waterlogging. Nevertheless, water should be able to be stored well. The organic matter content should not be too high so that the structure remains stable over the years and the roots get enough oxygen. In addition, the garden art of bonsai is not limited to just one plant species. Many different species with different demands on soil conditions can be trained to be bonsai. Depending on the bonsai species, a small variation of the bonsai soil may be necessary. With this article we will help you to choose a suitable soil for your botanical artwork.
Why does the bonsai need special soil?
In order to be able to speak of a bonsai, the miniature trees must be cultivated in a suitable pot. This means that the roots of the plants - unlike in their natural environment - only have a very limited space available. This spatial limitation ensures the strong growth brake, which is what makes the miniatures possible in the first place. By choosing the right coarse-grained, structurally stable bonsai soil ensure adequate root aeration and the right balance between water storage and drainage, even with years of pot culture.
This is what the perfect bonsai soil looks like
Due to the culture in the pot, you should attach great importance to the right soil for your bonsai. The requirements of different bonsai species vary. In general, however, the substrate used should have the following properties:
- Good nutrient storage
- Quick drying of the surface
- Well ventilated due to coarse grain
- Sufficient water storage despite good water drainage
- Good structural stability, which prevents the substrate from collapsing
- High buffer capacity against fluctuating pH values
- Low organic content
In order to have these properties, bonsai soil contains ingredients such as pumice, lava chippings, zeolite, expanded clay and sand and only a small amount of bark humus or peat. Akadama earth, dried volcanic ash clay from Japan, is also often included because of its beneficial properties. Special bonsai soils for plants that prefer a low pH contain Japanese Kanuma, granules also of volcanic origin, but lighter and more acidic than Akadama. Also from Japan comes the Kiryu earth, which is extremely dimensionally stable and stores water very well. It is mainly used for juniper and pine bonsai. Compost can also be contained in small amounts as a nutrient store, but more so in the production of the bonsai and less in further cultivation. Some possible ingredients and their properties are shown below.
| ingredient | properties |
|---|---|
| Akadama Earth | Structurally stable, water storage, ventilation |
| pumice | Mineral, volcanic powder, water and nutrient storage, structurally stable |
| expanded clay | Water storage, drainage, ventilation, structural stability |
| humus | Nutrient storage, not structurally stable, variable pH |
| fine gravel | Drainage and ventilation, structurally stable |
| perlite | Drainage and ventilation, structurally stable |
| sand | Fast drying, structurally stable, drainage |
| kanuma | Structurally stable, aeration, low pH |
| Kiryū | Structurally stable, water storage, very good ventilation |
| gravel | Drainage, structurally stable |
| volume | Nutrient storage, water storage |
| Clay | Mixture of clay and sand |
| peat | Water storage, aeration, low pH, not quite structurally stable |
| coconut substrate | Depending on the fineness for ventilation or as a water storage, not quite structurally stable |
| zeolite | Nutrient and water storage, structurally stable |
In the right combination, the above substances can be used as a substrate for your bonsai. The exact composition depends on the species you want to grow into a bonsai. Plants from tropical areas with high humidity such as fig species (ficus) or fukien tea (Carmona microphylla) preferably in soil with good water-storing properties. Species that are sensitive to waterlogging enjoy particularly good drainage.
The condition and age of the plant also influence the correct composition. Sick or young plants need a coarser grain than slow-growing and older plants, because the roots can spread faster in the loose structure. The suitable soils for bonsai can be derived very roughly by dividing them into needle-bearing and leaf-bearing types. In addition, you should also consider whether you are dealing with an indoor or an outdoor bonsai. However, since this is only a rough classification, there is plenty of scope for a dispute about the most suitable mixture.
A good choice for many beginner bonsai is one Basic bonsai soil. These high quality mixes are well suited for many types of bonsai or can be optimized by mixing in other ingredients.
Mix bonsai soil yourself
Here are a few promising recipes for the gardener who wants to put together his own bonsai soil.
The following mixtures are recommended for conifers:
- 2:2:1 sand, clay and peat
- 1:1:1 Akadama, pumice and lava granules
- 1:1:2 Kiryu Earth, Pumice, and Akadama
A high water storage capacity is important for deciduous trees or indoor bonsai, but the trees are usually satisfied with low drainage. For example, the proportion of sand goes down and the proportion of clay goes up.
Examples of good mixtures for deciduous trees are:
- 2:2:1 peat, loam and sand
- 2:1:1 Akadama, pumice and lava
- 1:1:1 Akadama, Kanuma and Pumice
Mixtures like these are suitable for the bonsai on the windowsill:
- 2:1:1 Akadama, humus and fine gravel
- 1:1:1 soil, peat and pumice
If you want to plant your bonsai in substrate that is exactly adapted to the species, you should first consider the needs deal with the plant and then adjust the mixing ratio in a suitable manner or add other components add to. Suggestions for substrate selection for the most popular indoor and garden bonsai can be found here.
Buy bonsai soil
An easier way to find the right substrate is to use universal ones Basic bonsai soils, which can be adjusted with some aggregates if necessary. Mixing in other ingredients will not always be necessary if less special bonsai are grown. However, if you dare to try something trickier bonsai species, you should find out more about their soil requirements.
Based on such Basic bonsai soil For example, the ventilation can be improved with perlite, gravel, sand or expanded clay, which, however, also reduces the water storage capacity. The water storage can be increased with clay, fine coconut fibre, peat or bark humus. clay and more mature compost can be mixed in to store nutrients - but caution is advised: compost is not structurally stable for long, so the substrate will sag and aeration will deteriorate.
Tip: The best substrate is of no use to your bonsai if the pH value in the pot is not right. Therefore, pay particular attention to acid-loving bonsai species such as the azalea and just test the pH of your mix before use. The pH value can be corrected up or down with acidic kanuma, peat or lime - and the subsequent fertilization and watering should also maintain the appropriate pH value.
As your Water bonsai properly find out in this article.
Many thanks to Floragard for the support!
