Soil composition is a key element in the life and growth of Bonsai. In order to achieve success when growing Bonsai one must consider the type of soil used to grow the tree in. While there is no magic recipe or formula for soil composition, there are many factors to consider in allowing one to make an informed decision on what soil mixture to use.
Two of the main considerations for Bonsai soil involve drainage and nutrients. First, is imperative that the soil allows for adequate drainage. Secondly, the soil should be able to retain nutrients and water for the Bonsai to absorb. Choosing the right mix of soil to use for growing Bonsai tends be a subjective matter among growers and a skill that develops with experience. For a beginner, one may even consider a pre-made mixture that can be found at a local nursery or garden center.
For those who are more daring, and want to mix their own soil, there are organic and inorganic soil mixes to choose from. Organic soil mixes are basically a combination of dead plant matter and grit. This combination allows the water and nutrients to be held for the tree to absorb while the grit provides a medium to facilitate drainage. Inorganic soil is made of material that has never been alive and contains no nutrients. This includes materials like clay and volcanic rock. When using inorganic soil alone it will be necessary to provide fertilization for the Bonsai. However, unlike organic material, which can hold too much water and breaks down quickly, inorganic material keeps its structure and does not retain an excess of water. While using either an organic or inorganic medium alone is not unheard of, making a mix of both materials can produce a basic blend, which becomes a more useful soil. This mixture can help balance the Bonsai’s need for nutrients, water and drainage.
Regardless of the exact mixture used for the soil, the particles should always be run through a sieve, in an attempt to make them uniform in size. It is important for the components to be the same size because pieces that are too large or small can inhibit proper drainage.
Other factors will also determine what mix of soil should be used in growing your Bonsai. These include the type of tree being grown and its nutrient and water requirements, as well as the size of the pot being used and the surrounding climate. Finding the perfect soil composition for your Bonsai will take some careful consideration and experimentation, and in the end contribute to its development as true work of art.