Fertilizing

Because bonsai trees are cultivated in limited amounts of soil, adequate feed is very important. As a general rule, a small amount of feed is given in the spring and a larger amount in the fall. Feed for bonsai should contain three principle ingredients; nitrogen, phosphoric acid, and potash. It is also a good idea to use a fertilizer containing "chelated" iron. Water before fertilizing your
tree and then apply at half the strength recommended by the brand's manufacturer. Rotate the use of brands since different manufacturers add different amounts of trace elements and minerals. You could also add Superthrive, which is a vitamin supplement to the fertilizer mix. You may find it simpler and easier to use slow release fertilizer granules (placed over the soil)
whose nutrients are released with each watering.

Opinions about soil mixes and fertilization vary widely among practitioners. Some promote the use of organic fertilizers to augment an essentially inorganic soil mix, while others will use chemical fertilizers freely. Bonsai soils are constructed to optimize drainage. Bonsai soil is primarily a loose, fast-draining mix of components, often a base mixture of coarse sand or gravel, fired clay pellets or expanded shale combined with an organic component such as peat or bark. In Japan, volcanic soils based on clay (akadama, or "red ball" soil, and kanuma, a type of yellow pumice) are preferred.