Bonsai plants are placed in very small containers so they take in little amounts of nutrients. That is why using a bonsai fertilizer is very important. Fertilizing bonsai regularly and properly ensures the bonsai will grow healthy and in a controlled manner.
All bonsai fertilizer provides the following substances – Nitrogenous (N) for general tree growth, Phosphorus (P) for fruit and bud development, and Potassium (K) for increasing adaptability of the bonsai during winter. Each bonsai fertilizer will feature an NPK value referring to these substances. The NPK value of a bonsai fertilizer is important to determine the right fertilizer to use at a particular season. Calcium and sulfur are other substances of a bonsai fertilizer.
Because nitrogenous encourages growth, you need a bonsai fertilizer with a high content of this in the early spring. Likewise, since potassium prepares the bonsai plant for winter it means it inhibits growth so you would need to select a bonsai fertilizer with a high potassium or K value for use in late summer and fall.
Determining the right NPK value is the key in choosing a bonsai fertilizer. Armed with this knowledge, you do not need to spend too much on special fertilizers although some can be useful for spring and autumn use.
When to use a bonsai fertilizer
Usually, bonsai fertilizing is done at the start of the spring until fall. You can apply a firm bonsai fertilizer monthly and a liquid bonsai fertilizer every week. Ideally, the firm one is used for the soil and the liquid form is applied to the leaves.
How to use a bonsai fertilizer
The recommended quantity of bonsai fertilizer to use is half of that for regular plants. Wait two months after repotting before fertilizing a bonsai. Apply more fertilizer on a young bonsai that you will style soon. Make sure to use a bonsai fertilizer with the correct NPK value in the right season.
Select a bonsai fertilizer with a value of 10N-5P-5K for use during early spring and summer to promote growth and for bonsai trees that are already styled, select a bonsai fertilizer with low N value. A bonsai fertilizer less nitrogenous and high potassium is ideal to stop growth and make the bonsai ready for winter. A bonsai fertilizer with a 3N-10P-10K value is recommended for use in late summer and during fall.
Fertilizing bonsai leaves
Dissolve a liquid bonsai fertilizer in water as per product instructions and spray on the leaves of your bonsai plant. This will produce larger leaves so apply on bonsai that you are still training.