Fertilizing regularly during the growing season is crucial for Bonsai to survive and thrive. Trees are usually able to extend their root system in search of nutrients, but since Bonsai are confined to the relatively small pots they are planted in, they need proper fertilization to replenish the soil's nutritional content.
There are three basic elements in any fertilizer; Nitrogen, Phosphorous, and Potassium (NPK.) Nitrogen increases the growth of the leaves and stems or the growth above ground. Phosphorus contributes to healthy root growth and the growth of fruits and flowers. Potassium enhances overall plant health. Growers often use different ratios of NPK for different trees and at different times of the year. However, experts are increasingly recommending using the same NPK ratio throughout the Bonsai growth cycle. Apart from the three macronutrients (NPK), fertilizers can also include a range of micronutrients like Iron, Manganese, Boron, Molybdenum, Zinc, and Copper.
Most Bonsai trees should be fertilized during the entire growing season; early spring through mid-autumn. Older and more mature trees are often fertilized less frequently, depending on the species, time of year, stage of development, and health of the tree. Indoor trees can be fertilized all year round. Check our care guides for specific information about when to fertilize each specific tree species.
It is important to choose the right fertilizer for your Bonsai plants and apply the right quantities. We recommend using a relatively high Nitrogen content fertilizer like NPK 10:6:6. in spring, a more balanced fertilizer like NPK 6:6:6 is more optimal for summertime, and a low Nitrogen fertilizer like NPK 3:6:6 for autumn. More and more, experts are favoring using a balanced fertilizer throughout the growing season, and slowly decreasing the amount applied towards the end of the growing season.
Subtropical tree species are usually kept indoors and don't experience seasonal changes. They grow year-round and need to be fertilized consistently. For indoor Bonsai, we recommend a balanced liquid fertilizer. Follow the guidelines as stated on the product packaging.
There are a few exceptions worth pointing out for using varying ratios of NPK. Using a high Phosphorous fertilizer like NPK 6:10:6 can help promote the flowering growth of a Bonsai tree. Using a fertilizer with a slightly lower Nitrogen content or reducing the amount of fertilizer used can be advantageous for older or more mature Bonsai.
Bonsai fertilizer is like any other, but buying from an online Bonsai shop will ensure you find the right NPK values to promote Bonsai growth. Biogold is a favored fertilizer among Bonsai enthusiasts, but any fertilizer with the right NPK value is perfectly fine. There is a wide variety of liquid, solid, synthetic, and organic fertilizers. What type of fertilizer you use, doesn't matter, but you have to make sure to carefully follow the application guidelines as stated on the product’s packaging.