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 bowl that does a big job. With its rather sparse content, it has to provide the tree's livelihood. Because the plants draw their water and nutrients from the soil in the shell and find support. It is not true that less soil also requires less work or accuracy. On the contrary - due to the small volume of earth there is hardly any room for errors. This is not only reflected in the care of the miniature trees, but also in the choice of the right substrate for your bonsai.
You should consider this before buying bonsai soil
Without making the right soil choices, you will be unlikely to succeed in keeping your bonsai healthy for years. Bonsai soil should have certain properties: The irrigation water must drain off well to avoid waterlogging. Nevertheless, water should be able to be stored well. The content of organic matter should not be too high so that the structure remains stable for years and the roots get enough oxygen. In addition, the art of bonsai gardening is not limited to just one type of plant. Many different species with different demands on the soil conditions can be trained to become bonsai. Depending on the type of bonsai, a small variation of the bonsai soil may be necessary. With this article we will help you choose a suitable soil for your botanical work of art.
Why does the bonsai need special soil?
In order to be able to speak of a bonsai, the miniature trees have to be cultivated in a bowl that suits them. This means that the roots of the plants - unlike in their natural environment - only have a very limited space available. This spatial limitation prevents growth, which is what makes the miniatures possible in the first place. With the right choice of a coarse-grained, structurally stable Bonsai soil ensure adequate root aeration and the right balance between water storage and drainage, even after years of shell culture.
This is what the perfect bonsai soil looks like
Due to the culture in the bowl, you should attach great importance to the right soil for your bonsai. The demands of different types of bonsai vary. In general, however, the substrate used should have the following properties:
- Good nutrient store
- Quick drying of the surface
- Well ventilated due to the coarse grain
- Sufficient water storage despite good drainage
- Good structural stability, which means that the substrate does not collapse
- 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 admixture of bark humus or peat. Akadama soil, 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 value contain Japanese Kanuma, a granulate of volcanic origin, but lighter and more acidic than Akadama. The Kiryu earth, which is extremely dimensionally stable and stores water very well, also comes from Japan. It is mainly used for juniper and pine bonsai. Even compost can be contained in small proportions as a nutrient store, but more in the production of the bonsai and less in the 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, structurally stable |
| humus | Nutrient storage, not structurally stable, variable pH value |
| Fine gravel | Drainage and ventilation, structurally stable |
| Perlite | Drainage and ventilation, structurally stable |
| sand | Quick drying, structurally stable, drainage |
| Kanuma | Structurally stable, ventilation, low pH |
| Kiryu | 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, ventilation, low pH value, not entirely structurally stable |
| Coconut substrate | Depending on the fineness for ventilation or as a water reservoir, not completely 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 that you want to grow into a bonsai. Plants from tropical areas with high humidity such as fig species (Ficus) or Fukientee (Carmona microphylla) rather in soil with good water-storing properties. Species sensitive to waterlogging enjoy particularly good drainage.
The condition and age of the plant also have an influence on the correct composition. Sick or young plants need a coarser grain size than slow-growing and older plants, because in the loose structure the roots can spread faster. The right soils for bonsai can be roughly derived by dividing them into needle-bearing and foliage-bearing species. In addition, you should also consider whether you are dealing with an indoor or an outdoor bonsai. Since this is only a rough classification, there is a correspondingly large amount of leeway for a dispute about the most suitable mixture.
A good choice for many beginner bonsai is one Base bonsai soil. These high-quality mixtures are well suited for many types of bonsai or can be optimized by adding other ingredients.
Mix the bonsai soil yourself
Here are a few promising recipes for gardeners who want to put their own bonsai soil together.
The following mixtures are recommended for conifers:
- 2: 2: 1 sand, clay, and peat
- 1: 1: 1 Akadama, pumice gravel and lava granulate
- 1: 1: 2 Kiryu earth, pumice and Akadama
In the case of deciduous trees or indoor bonsai, a high water storage capacity is important, but the trees are usually satisfied with a low drainage. For example, the proportion of sand goes down and the proportion of clay goes up.
Good mixtures for deciduous trees are, for example:
- 2: 2: 1 peat, clay and sand
- 2: 1: 1 Akadama, pumice and lava
- 1: 1: 1 Akadama, Kanuma and pumice gravel
Mixtures like these are suitable for the bonsai on the windowsill:
- 2: 1: 1 Akadama, humus and fine gravel
- 1: 1: 1 earth, peat and pumice
If you want to plant your bonsai in a substrate that is precisely 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 additional components add to. You can find suggestions for the choice of substrate for the most popular indoor and garden bonsais here.
Buy bonsai soil
A simpler way to find the right substrate is to use universal ones Basic bonsai soilwhich can be customized with some aggregates if necessary. It will not always be necessary to mix in other ingredients if less special bonsai is grown. However, if you dare to try a little trickier bonsai species, you should find out more about their soil requirements.
Starting from such a Base bonsai soil For example, ventilation can be improved with perlite, gravel, sand or expanded clay, but this also reduces the water storage capacity. The water storage can be increased with clay, fine coconut fiber, 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 that the substrate will sag and the ventilation will deteriorate.
Tip: The best substrate is of no use to your bonsai if the pH value in the pot is wrong. So pay special attention to acid-loving bonsai species such as the azalea and test the pH value of your own mixture before using it. The pH value can be corrected upwards or downwards with acidic kanuma, peat or lime - and the subsequent fertilization and watering should also keep the appropriate pH value.
Like your Water bonsai properly learn from this article.
Many thanks to Floragard for their support!
