Akadama Soil


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Akadama soil in a binsai tree pot.

Akadama soil has been used for growing bonsai in Japan for centuries. It is the soil of choice for serious bonsai practitioners. 

Akadama has been part of the bonsai culture for generations.  The soil is as integral to the practice and art of bonsai as the plants and trees that thrive in it.

Akadama soil in a binsai tree pot.
Akadama bonsai soil.

What is akadama soil?

The word akadama means “red ball soil”. It is a granular clay of volcanic origin that is dug from the ground. It is then dried and sieved to separate it into various sizes. 

After the separating process is completed, the soil is then fired in kilns to remove any organic material. The resulting soil is very stable and relatively inert. 

Akadama can be used by itself or as part of a special mix.

Properties and benefits of akadama

pH neutral

It is generally pH neutral making it a great material for growing almost any plant because the pH can be manipulated according to the species requirements. 

Good drainage

There is very little ‘dust’ or loose particulates in akadama and for this reason it doesn’t necessarily appear to be a very good potting medium compared to the familiar western mixes of sand, compost, soil and peat. 

This is not actually the case, and in fact akadama has a particular property essential to bonsai plants and trees – it drains really well, yet it retains moisture and nutrients in its tiny pores and crevices (unlike sand or pebbles). 

The drainage in combination with its unique quality of moisture retention allows the root system to absorb nutrients and water more efficiently promoting healthy growth. 

Watered akadama bonsai soil (light and dark brown).
Akadama soil, recently watered (Abrahami, CC BY-SA 3.0, via Wikimedia Commons)

Healthy soil

The soil will not become water logged, and the requirement to constantly replenish fresh water and fertilizer also prevents mold and fungus from growing. 

Well aerated

Another benefit of akadama soil is that is allows the free passage of air to the plant’s root system.

If a soil is used for growing bonsai that compacts and becomes dense, air can be excluded from the root system, creating an imbalance. This imbalance does not allow the roots’ proper nutrient transfer and the tree can die. 

The correct mix of air, water and nutrients are especially important to a container bound plant.

Good aesthetics

Akadama soil is also very pleasing to the eye. It also aids the easy maintenance of the ground surface of a bonsai.

The grains around the bonsai can be easily kept clean and tidy by sweeping. Any weeds can be removed easily and without disturbing the the roots of the bonsai as would be the case if a heavy soil were used.

Easy repotting

Akadama is long-lasting, and does not need to be replaced since it does not decompose. It is much easier to repot a specimen that is rooted in akadama since this soil does not compact. This makes the process a much less traumatic experience for the plant or tree.

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