Bonsai Fertilizing

Healthy bonsai need to be fertilized regularly. The most important elements in the bonsai fertilizer are potassium (K), nitrogen (N) and phosphorus (P). Other elements appear in fewer quantities and are not as important. To give you a general idea, nitrogen (N) promotes leaf and branch development and growth in general. Phosphoric acid (P) enhances root and cell tissue development. Potassium (K) helps production and circulation of sap, flowering and fruiting.

With so many different bonsai fertilizers available in the store, it can be very overwhelming to pick the right one for your bonsai tree. Bonsai fertilizers are applied in two basic forms solid and liquid. There are few types that you can buy:

Inorganic granules are relatively inexpensive and very easy to use. It has a slow-release formula and because it is produced from chemicals it is more durable and will last longer than organic fertilizer. All you need to do is to scatter granules all over the soil surface. Don’t mix it with the soil to avoid root burn.

Inorganic liquid fertilizer needs to be mixed with water and applied during watering times. Unfortunately, heavy rains often wash a lot of it away so it needs to be reapplied every two weeks. It is also very inexpensive and easy to find at your local nursery, supermarket or garden center.

Traditional Japanese bonsai fertilizer comes in organic blocks. It is not easy to find at your local store and it is expensive comparing to inorganic.

Keep in mind that the fertilizer you choose is not as important as using it correctly. Never exceed the amount specified on the package label. The fertilizer requirements of plants vary throughout the year and bonsai’s age and type. Start feeding your bonsai in the spring when you see the first few new leaves. From spring to fall you can use general fertilizer. Closer to fall your bonsai starts to set new flower buds for next year, so it is time to reduce nitrogen and increase phosphoric acid and potassium.

The rule of thumb is that you need to feed the plant only when it is in active growth. Fertilizing bonsai at the wrong time can change the growth schedule which can be very harmful for the tree. After repotting your bonsai, wait at least three weeks or until the plant is displaying active growth before feeding it.