You can grow bonsai in nearly any type of soil, however if you are concerned about their health at all times, then you should use the correct soil or bonsai potting mix.
Some of the key features of Bonsai potting soil
You want the bonsai soil to hold enough nutrients, water, and air for the roots of your bonsai tree to receive these three necessary elements consistently. Some of the key features of a bonsai potting soil are as follows:
- Dry in texture – The soil should be dry in order to facilitate mixing and potting. If the soil is dry, it will flow freely around the roots of a tree. As a result, the roots will always be in good contact with the soil.
On the other hand, when the soil for bonsai is wet, repotting the bonsai tree can be quite challenging, for example, as you will have difficulty working into and around the root system.
- Firm – The bonsai potting mix should be firm enough in order to secure the tree in the pot. Bonsai growers often use wires to hold the tree in the pot to prevent it from moving around and also help it form a good root structure. These wires are secured in the soil. A firm soil facilitates this practice.
- Open, porous and granular – In order for a root system to breathe, soil mixtures must have open spaces and incorporate as much air as possible around the soil granules.
- Well draining – Bonsai potting soil’s texture should be open and well-draining in order to let excess water drain off. As, too much moisture in the soil can promote root decay.
Therefore, one of the most critical aspects of bonsai tree gardening is the use of well-draining soil.
Various types of Components of a Bonsai soil
Bonsai culture can be performed with a variety of soil types. Bonsai growers use these bonsai growing mediums individually (such as the commercial bonsai potting mix) or mix them in different proportions depending on the bonsai plant or growing conditions.
It is not uncommon for bonsai growers to develop their own recipes, generally using the components listed below.
Bonsai soil Inorganic components
- Chic, chicken or turkey grit ( Fine, medium or course grit) – Varying in colors, these particles are heavy and are used in bonsai potting mix for facilitating good drainage.
- Akadama – A granular mineral that is reddish in color, akadama is mined in Japan and is available in a range of sizes and grades. It helps in providing the bonsai soil with a great balance of moisture and air. However, if used alone, it has a tendency of staying wet for a long time. In Japan, it is one of the most common bonsai potting mediums.
- Kanurna – It is also mined in Japan. It is as popular as akadama in Japan. Acid loving bonsai trees respond well to bonsai potting soils containing Kanurna.
- Kiryu – It means “river sand”. It lacks nutrients, however, it is highly porous and assists in good water drainage.
- Decomposed granite – Much like grit, it is used in bonsai tree soil for good drainage.
- Crushed lava rock – For good drainage.
- Turface – It is high fired calcined clay and has rock like texture. It is used to give the bonsai potting soil a good balance of drainage and water retention. It also promotes good air circulation for the roots of the bonsai tree.
- River stone – For good drainage.
- Sand – For good drainage. Use a coarse textured sand. Fine and salty sand from the beach is not recommended.
- Gravel – For good drainage.
Bonsai soil Organic components
- Commercial Bonsai potting mix – Various types and compositions depending on the brand and the plant
- Humus (Decomposed leaves)- The top soil formed after the decay of organic matter such as twigs, leaves and animals.
- Pine Needles – Acidic in nature. Pine needles gradually decay as compared to other organic matters. Used in bonsai soil to hold minerals and moisture. However, they could carry diseases.
- Akadama and humus mix – This mix provides good drainage along with good organic matter content.
- Shredded bark (bark chips) – Shredded bark particles of size 1/8 to 3/8 of an inch. Much like pine needles, they are also used in bonsai tree soil to hold minerals and moisture. bark chips also gradually decay as compared to other organic matters.
- Ericaceous compost – This compost is added to Bonsai soils meant for acid loving bonsai trees. The pH of these types of compost is around 4 to 5.
- Commercial compost – General purpose compost for any bonsai soil.
- Peat moss – Antifungal and antibacterial in nature, It not only provides antiseptic properties but also helps in retaining moisture. However, as it ages, it starts to become water repellent in nature.
- Garden soil – A loam garden soil.
IMPORTANT NOTE : Cocoa shells (aka Cocoa Hulls or Cocoa Husks) shall not be used in bonsai soils as they very easily break down and retain a lot of water. Cocoa shells are also toxic to house pets such as dogs.
How to make bonsai soil mix recipe at home
Now that we have got the components of bonsai soil out of the way, we can talk about how to make homemade bonsai soil and few Bonsai soil mix recipe.
Some key characteristics of a bonsai soil to remember before you start making your own bonsai soil mix:
- There may be just one ingredient in bonsai soil or a mixture of more than one ingredient, but it is imperative that these ingredients are of good quality in order to keep your tree healthy, spirited for many years and maintenance to a minimum.
- Organic and inorganic components should both be included in a proper bonsai growing medium.
- While the organic components of bonsai tree soil will break down into finer particles, the inorganic components will remain stable as time goes on. Gaseous exchange and drainage are impeded by the finer particles. The soil for bonsai eventually becomes less porous and water-retentive.
- It is the soil composition that determines the long-term usefulness of bonsai soil.
- Unlike bonsai soil composed exclusively of inorganic components, organic bonsai soil needs to be replaced more frequently.
Bonsai soil mixes differ in pH, CEC (cation exchange capacity), bacteria and fungi content, fertility, and many other factors.
Bonsai growers commonly use a mixture of organic and inorganic ingredients to make their bonsai soil mixtures.
In reality, bonsai soil mixes are never perfect i.e. there is no best bonsai soil. As you gain experience, you will start playing with different blends depending on the climate and your bonsai tree needs.
Some bonsai growers might add nutrients and supplements like fertilizers, hormones, fungal spores etc to get the best bonsai soil for them. On the other hand, some bonsai enthusiast might be satisfied by using only one bonsai soil component.
No matter what style or philosophy of bonsai tree soil making you adhere to, one thing is certain, you will save money. Especially when compared to the prices of imported Japanese bonsai soils, or in the case where you have to re-pot a bunch of bonsai plants in containers.
Don’t use commercial bonsai potting soil right away. It is common for bags of soil for bonsai tree to contain fine particles, which will hold moisture for a very long period of time. Never use regular potting soil.
Either you use a commercial bonsai potting mix or you plant to make your own bonsai potting soil, use a fine sieve measuring 3 – 6 mm (1/8 to 1/4 of an inch) or window screen and sift each ingredient. This will help you in removing the finer particles of the soil which are not good for a bonsai potting soil as they tend to clog the root system. Discard these fine particles and only use the soil remaining in the sieve.
Important note : To make your bonsai soil mix, make sure that all the components are completely dry. This will yield the best bonsai soil for your needs.
How to make bonsai soil ?
Method 1. DIY Bonsai soil
- One part bonsai potting soil or Small bark chips (1/8 to 3/8 of an inch).
- One half chicken grit (1/16 to 3/8 of an inch) or gravel or crushed red lava rock or even aquarium gravel.
These simple blends keep moisture in and allow air to reach the roots.
Method 2. DIY Bonsai soil
- One part peat moss.
- One part loam Or commercial bonsai soil mix.
- Two part coarse grit 3 – 6 mm (1/8 to 1/4 of an inch).
Grit with very sharp edges should not be used because they might severely damage the roots at the time of repotting the bonsai tree.
While using commercial bonsai soil mixture, adjust the amount of grit and supplements as commercial bonsai soil mix already has supplements and grit added to it.
Do not mix fertilizers in the bonsai potting soil while potting the plant. Add the fertilizers later when the bonsai tree is growing.
Take a look at the components list mentioned above in the article to replace any ingredient in these bonsai soil recipes depending on availability and price.
Method 3. DIY Bonsai soil (Basic recipe)
- One part grit
- One part organic matter
This diy bonsai potting mix will be suitable for almost all the bonsai trees. Additionally, you can also add up to 20 percent of a soil improver, as well as about the same proportion of Akadama. These additives will help in maintaining the porosity of the potting soil on the longer run ( as organic matter will break down into smaller particles).
Do bonsai need special soil ? or Do bonsai trees need special soil ?
Answer: Bonsai trees can grow well in a homemade bonsai soil with basic components like bark chips and gravel. This diy bonsai soil will give enough porosity and water retention needed by bonsai growing medium. However, there is indeed special soil requirements for bonsai depending on the type of bonsai you wish to grow.
Imported soils (from Japan) such as akadama, kanuma and kiryu provide ideal growing conditions for bonsai. The clay granular soil akadama is suitable for most bonsai. For bonsai plants in acidic soil, such as azaleas, kanuma is highly recommended. Kiryu is best for pines and junipers.
What is the best soil for bonsai tree ? or best potting soil for bonsai ?
Answer: The definition of best potting soil for bonsai changes from variety to variety. However, there are certain Japanese soils which are considered as best for certain types of bonsai plants. The clay granular soil akadama is suitable for most bonsai. For bonsai plants in acidic soil, such as azaleas, kanuma is highly recommended. Kiryu is best for pines and junipers.
what soil to use for bonsai ?
Answer: Any soil which is firm, porous, well draining and dry can be used for growing bonsai. For the bonsai potting soil to achieve porous and airy texture, grit or gravel or coarse sand can be added. Most important factors are the soil should be granular and not contain fine particles and the soil should be well draining.
Can i use cactus soil for bonsai ?
Answer: Yes you can use cactus soil for growing bonsai. Cactus soil and bonsai soils are very similar in characteristics i.e. they are both light, firm, porous and well draining. Additionally, both the soils have a good balance of water retention and drainage.
Can you grow bonsai in normal soil ?
Answer : As long as the soil is light, firm, porous and well draining, it can be used for growing bonsai. However, the “normal soils” do not posses all the qualities a bonsai potting soil might need. Opting for a bonsai specific soil is preferred.
Can you use indoor potting soil for bonsai?
Answer : You can use indoor potting soil for bonsai only after you mix that soil with gravel or grit or coarse sand to add porosity to the potting soil.