The green miracle:
All green plants, and therefore our bonsai, perform a true miracle! Through the process of photosynthesis, they are able to produce carbohydrates from carbon dioxide and water to feed themselves. Ultimately, it is the plant carbohydrates in the form of sugar, starch or cellulose that the entire animal kingdom feeds on! In this sense, plants should be revered and bonsai culture is certainly not a bad approach here!
Main nutrients:
The main nutrients for the process of photosynthesis are carbon, oxygen and hydrogen. Here it becomes clear how important air and water and of course sunlight are for a plant to feed itself adequately. However, other nutrients are needed for growth, flowering and fruiting. Nitrogen, phosphorus, potassium, magnesium, calcium and sulfur are the most important for building proteins, fats, vitamins, hormones and chlorophyll. In addition, there are other important trace nutrients, which the plant should also not lack.
Mineral and organic fertilization:
Since a bonsai grows in a pot, the nutrients that occur naturally in the soil, such as nitrogen, phosphorus and potassium, are not available to it. For this reason, the bonsai must be fertilized regularly. This is done either directly through a mineral fertilizer or indirectly through an organic fertilizer. With a mineral fertilizer, the nutrients are immediately available to the plant. With an organic fertilizer, the microorganisms must first mineralize the ingredients. We combine mineral and organic fertilization during the growing season. The mineral fertilizer is given in liquid form at intervals of two weeks. In addition, organic fertilizer is applied in solid form as needed.
Timing:
Organic fertilization of outdoor bonsai begins in spring after the new leaves have fully sprouted. Mineral fertilizers should be applied 14 days later. Freshly repotted plants in particular should not be fertilized too early, as this has a negative effect on root development. Bonsai that are still developing can also be fertilized before the leaves emerge. This promotes vigorous growth.
Indoor bonsai:
For practical and hygienic reasons, indoor bonsai are generally only fertilized with liquid fertilizer. This ensures that the plant is always supplied with sufficient nutrients and prevents the formation of mold and odors. From April to October, indoor bonsai are fertilized twice a week. In the winter months, only once, or not at all for subtropical plants if they are overwintered in the cold.
Overfertilization:
The main engine for plant growth remains the sun, water and heat. Fertilizer is also necessary for growth, of course, but could be understood here rather as "the salt in the soup". Nitrogen is important for strong growth, but if too much of this nutrient salt is given, the plant will be damaged. With mineral fertilizers, therefore, one must follow the recommended application and dosage. With organic fertilizers, this is less of a problem because the microorganisms provide balanced mineralization.
Autumn fertilizer:
In autumn we enjoy the colorful leaves of our bonsai. But the plant is much more concerned with storing important nutrients for the next year. When the plant begins to change color, this is also a good opportunity to provide it with a special autumn fertilizer (e.g. Potash Magnesia). The potassium salt contained in the fertilizer is stored in the cell sap and lowers the freezing point of the cell. This increases the frost resistance of the plant and additionally protects it from the cold season.