Fertilising

Why does my Bonsai need fertilising?

Plants draw their nutrients from sunlight, air, water and soil. A bonsai lives in a limited amount of soil, where nutrients are used up quickly, so regular feeding is essential to replenish them. Every bonsai from BONSO comes with a care kit that includes fertiliser and a fertiliser basket, enough for everyday needs.

N, P, K, each with its own role

The three numbers on a fertiliser package show the ratio of nitrogen, phosphorus and potassium. Knowing what each one does helps you choose the right fertiliser for the species and the season, matching what the tree needs at each stage of growth.

  • Nitrogen (N), the "leaf fertiliser", supports the growth of stems, leaves and trunks
  • Phosphorus (P), the "bloom and fruit fertiliser", promotes flowering and fruiting
  • Potassium (K), the "root fertiliser", regulates root development and overall condition

Types of fertiliser

Slow-release granular fertiliser
(our recommendation)

Characteristics: mineral or synthetically produced nutrients with a slow-release design

Strengths: precise nutrient content, odourless, clean and easy to control, releases nutrients gradually with each watering and rarely burns roots

Weaknesses: slower to take effect, and offers little improvement to soil structure over the long term

How to use: place in a fertiliser basket; the granules are moistened each time you water, releasing nutrients slowly

Liquid fertiliser

Characteristics: synthetically produced liquid fertiliser

Strengths: fast-acting, quickly absorbed, easy to control the dosage

Weaknesses: high concentrations can easily burn the roots

How to use: dilute with water as directed, then spray onto the foliage or apply to the soil

Solid organic fertiliser

Characteristics: made from fermented natural materials such as bone meal, soybean cake and oil cake, with Japanese Tamahi balls being a common example

Strengths: gentle, unlikely to burn roots, and improves soil structure and microbial life

Weaknesses: slow to break down, has an odour, and can attract flies and insects if not fully fermented

How to use: place in a fertiliser basket so it is not washed away when watering; replace Tamahi every two to three months

When should I avoid fertilising?

The feeding cycle depends on the species. In the situations below, feed sparingly or pause altogether:

  • During winter dormancy, or when the tree is weak
  • After heavy pruning or repotting, while the tree is under stress
  • Overfeeding a tree with a limited root system can cause fertiliser burn