Regular fertilization during the growth season is crucial for the survival and vitality of Bonsai trees. While trees in nature can develop extensive root systems to seek nutrients, Bonsai trees are confined to small pots and rely on fertilizers to supplement the soil with essential nutrients. Discover the key guidelines for successfully fertilizing your Bonsai and maintaining a healthy nutrient balance.
Before delving into the subject of fertilizing bonsai, it's important to understand the distinction between two categories: bonsai trees in development and bonsai trees in refinement.
A bonsai tree is considered to be in the development phase when:
The trunk has not yet achieved the desired size. Primary and secondary branches have not yet grown to the desired size or structure.
During the development phase, bonsai trees may or may not resemble the traditional bonsai aesthetic.
Bonsai in development
A tree is in refinement when:
The trunk and main branches are in place
The tree looks like a bonsai
Bonsai in refinement
There’s a lot to say about these stages, but for now I’ll make a single distinction. For trees in development, vigorous growth is desired. This produces trunk girth and branch complexity fast.
For trees in refinement, less vigorous growth is desired. We want greater numbers of smaller branches.
Now, on to the main topic.
Fertilizer
There are two basic categories of fertilizer – organic and inorganic.
solid organic fertilizer
liquid organic fertilizer
Choosing the Right Fertilizer for Your Bonsai
Selecting the appropriate fertilizer and applying the correct amount is crucial for the well-being of your bonsai tree. Typically, it is recommended to use a fertilizer with a relatively high nitrogen content (such as NPK 10:6:6) during the spring, a more balanced fertilizer (such as NPK 6:6:6) during the summer, and a low-nitrogen fertilizer (such as NPK 3:6:6) during the fall. However, an increasing number of experts prefer using a balanced fertilizer throughout the entire growing season, gradually reducing the amount applied towards the end of the season.
Tropical or subtropical species of bonsai are often kept indoors and, unlike outdoor bonsai, they are not greatly affected by weather changes. Indoor bonsai trees grow year-round and therefore require year-round fertilization. For indoor bonsai, it is advisable to use a balanced liquid fertilizer and follow the instructions provided on the product packaging.
There are a few exceptions to consider. To promote flowering in bonsai, a fertilizer with a high phosphorus content (such as NPK 6:10:6) can be used. For older trees, you may want to use a fertilizer with a slightly lower nitrogen (N) content or reduce the amount applied. While "bonsai-specific fertilizers" are essentially regular fertilizers, purchasing from bonsai specialty stores (including online shops) can help you find a product with the appropriate NPK ratio and content. Biogold is a popular product among bonsai enthusiasts, but any fertilizer with suitable NPK ratios and content will suffice. You can choose liquid or solid, inorganic or organic fertilizers; the differences are not significant. However, make sure to follow the instructions provided on the product packaging when applying the fertilizer.
How to Fertilize Bonsai Trees?
Fertilizing your bonsai tree should be done according to the recommended amount and frequency stated on the product packaging. You can slightly reduce the amount for trees that no longer require shaping, aiming for balanced growth instead of stimulating excessive growth. When using solid fertilizer, you can use a basket, fabric bag, or mesh bag to hold the fertilizer in place. Never over-fertilize, as it can have a detrimental impact on the tree's development.