The foundation of a healthy plant lies in its roots, and the soil it inhabits plays a vital role in ensuring access to essential elements like water, air, and nutrients. When it comes to cultivating bonsai trees, choosing the right soil becomes paramount to their well-being.
You can use regular soil for young bonsai trees, but it is not the best option for mature trees. Bonsai soil, made of akadama, lava rock, and pumice, is the best option for bonsai trees because it provides the water retention, drainage, airflow, and nutrients necessary for their health.
In this article, I will explore the suitability of regular soil for bonsai trees and why bonsai-specific soil is often the preferred choice. I will delve into the advantages of bonsai tree soil, examine the characteristics that define a healthy bonsai substrate, and make comparisons between regular soil and bonsai tree soil.
Using Regular Soil for Bonsai Trees
Traditional soil might not be the top choice for bonsai enthusiasts, but it can be a decent option for young bonsai trees, particularly during their initial growth phases. Nevertheless, as bonsai cultivation advances and the tree’s requirements change, shifting to bonsai-specific soil becomes essential.
Young Trees in Regular Soil
During their early growth phase, young bonsai trees resemble ordinary trees. At this stage, they can tolerate regular or potting soil, which supports root development crucial for maintaining the tree’s upright posture.
Transitioning to Bonsai Tree Soil
Once the young bonsai has established its root system, it needs to be repotted into bonsai tree soil to meet its specific requirements.
Bonsai Tree Soil Is the Ideal Choice
Bonsai tree soil, despite its name, does not contain regular soil. It is a carefully crafted mixture designed to cater to the unique needs of bonsai trees. This specialized soil comprises a variety of materials, with a focus on larger-grained substrates.
The core components of bonsai tree soil include:
Akadama (A Reddish Dried Clay Found in Japan)
Akadama is a special type of soil used in bonsai trees that has a unique feature of allowing roots to grow through its clay balls. Although it does not have its own nutrients, it can retain them from other sources, like mineral supplements or lava rocks. However, akadama degrades over time, so it needs to be replaced periodically.
The core components of bonsai tree soil include:
Lava Rock or Cooled Lava Bits
Lava rock is an essential component rich in minerals, vital for bonsai health. It boasts durability and does not degrade, making it indispensable for ensuring proper drainage, particularly in wet climates.
White volcanic pumice provides effective drainage and safeguards against root fungus. Its resistance to freezing makes it invaluable, especially in colder climates.
A bonsai tree soil mixture for tropical plants may benefit from a small amount of organic material. Adding pine bark or peat moss will slightly increase water retention, mimicking the tropical climate the trees are accustomed to.
The Needs of a Bonsai Tree Substrate
Bonsai substrates have a crucial role in ensuring that bonsai trees are healthy and thriving. They determine important factors such as water availability, airflow around roots, and nutrient content.
Although the exact mixture may differ for various tree species, some fundamental requirements remain consistent:
Balance of Water Retention and Drainage
Getting the balance of water retention and drainage just right can be quite challenging for most plants, and bonsais are no exception. Even though there are different types of bonsai species, most of them require moist soil.
It’s best to keep the soil slightly wet to avoid having to water the tree too frequently. Most bonsais need to be watered every 5 to 7 days, so their substrates can provide water access for about a week. However, too much water can be detrimental to the plant.
If the substrate doesn’t provide enough drainage, water pools around the bonsai roots, which can be unhealthy for the trees. This leads to the roots being cut off from air and prevents the tree from absorbing nutrients, which can cause root rot and mold growth around the roots.
Any of these issues alone or in combination can lead to the demise of your bonsai, and they are usually irreversible.
Regarding water retention, bonsai soil has much better drainage than regular soil and slightly less retention. This means that bonsai soil can maintain a moist environment better than regular soil, which can easily become too damp. You can adjust the mix of bonsai soil to meet the water retention and drainage requirements of different climates.
While you often think about plants taking in oxygen through photosynthesis, the roots also need oxygen. Oxygen gives roots the energy they need to absorb water and nutrients and helps them grow faster.
Airflow also helps protect the roots from root rot by preventing water from surrounding the roots entirely. On the other hand, too much airflow can dry out the roots.
Since the substrates in bonsai soil are larger pieces, there is more space in between to allow air to travel through the soil and, most importantly, around the bonsai roots. Regular soil without a high clay content does allow for moderate airflow around plant roots. Without soil analysis, it is difficult to determine your soil’s makeup and, by extension, aeration.
The great thing about bonsai soil is that you create the mixture, so you are guaranteed to have good aeration. Bonsai tree soil also has good water retention to balance the airflow, so the roots will not dry out.
One factor that has a significant impact on airflow is compaction.
When you think of soil compaction, large farm equipment usually comes to mind. In fact, many things can cause compaction, including rain, manual compaction, and settling over time. Compaction is dangerous for bonsai trees because it can crush the roots or cut off the airflow to the roots.
Bonsai soil is much more resistant to compaction than regular soil. In addition to the airflow provided by the large, hard material that makes up bonsai tree soil, it also helps resist compaction. Akadama will degrade over time, so replacing it every year or two is important in resisting compaction.
Regular soil is typically more susceptible to compaction. However, the degree of compassion risk depends on the soil makeup. For example, clay soil generally compacts very quickly and even faster in the rain.
Like most plants, bonsai trees take in nutrients through their roots. Therefore, their access to nutrients is determined by the soil or substrate in which they are planted. While you can always add fertilizer or supplemental nutrients to the pot, it is always best if bonsais can take nutrients naturally.
The nutrients in bonsai tree soil come from the lava rock. If your bonsai needs more nutrients, you can add more lava rock to the bonsai soil mixture.
Like the other factors we have discussed, a big concern with regular soil is that you just can’t tell its nutrient content without running many tests. Furthermore, the nutrient content of regular soil varies significantly based on the soil’s makeup.
For instance, soil high in silt will have more nutrients than other types of soil. On the other hand, soil high in sand or clay will not have many nutrients and may be unable to support the bonsai tree.
The best option for substrates for your bonsai tree is bonsai tree soil; bonsai tree soil is a mixture of:
- Lava rock
This mixture meets all the needs of a bonsai, including:
- Water retention
- Compaction resistance