Fertilize bonsai: procedure & the perfect fertilizer

Even the smallest tree needs nutrients from time to time. We show when and how to fertilize your bonsai and which fertilizer is best suited for this.

Just like its free-growing counterparts, caring for a bonsai involves regular feeding. The correct fertilization does not only depend on the plant species that was raised to become a bonsai. The location, the season and the weather conditions are also reflected in the nutrient requirements. In addition, the culture in high-quality bonsai soils brings with it a few special features. This must also be taken into account when choosing the fertiliser, the amount of fertilizer and the time of fertilization.

Since the bonsai has to make do with a relatively small volume of soil, its care requires particularly careful and well-dosed fertilization. But caution is not only required because of the limited root space: Since very different tree species can be trained to bonsai, there is no universal bonsai fertilizer. In the following article, however, we would like to introduce you to the general basics of bonsai fertilization.

When should bonsai be fertilized?

First of all, your bonsai should be fertilized every time you transplant it. Repotting is done in early spring and old substrate is removed from the roots of the bonsai as completely as possible and the roots of the sapling are slightly shortened. The selected bonsai soil is then fertilized with 20 grams of horn shavings per square meter. So there is just one teaspoon on a small bonsai bowl. The horn shavings provide nitrogen and phosphate for a long time and thus serve as basic fertilization.
After planting, you should not fertilize for four weeks. The horn shavings do not release any nutrients in this short time - and that's a good thing, because the lack of nutrients stimulates the bonsai's root formation.
Then regular fertilization begins, the spacing of which depends on the choice of fertilizer. The fertilization takes place from the spring budding into the autumn and is paused in winter. After all, our photosynthesizers run in the cold seasonGarden dwellers on the back burner and quickly react negatively to too much fertilizer.

In the case of evergreen indoor bonsai, which are not so strongly exposed to the course of the seasons, the throttling of the nutrient requirement is also limited. This means that with indoor bonsai you have to provide energy with regular fertilizer applications even in winter. However, fertilization and watering of the bonsai is reduced in winter. If a plant is ailing, you should first rule out whether over-fertilization could be the reason. The nutrient supply is initially stopped in order to wait for any improvement. If you have ruled out over-fertilization, you can resume fertilization. If over-fertilization is the problem, the bonsai can even shed its leaves prematurely. Here you can find out what other reasons a bonsai can have for dropping its leaves.

Summary: when to fertilize the bonsai?

• Plant fertilization: 20 g/m² horn shavings, then stop fertilizing for 4 weeks
• Garden Bonsai: spring to autumn; do not fertilize in winter
• Indoor bonsai: spring to summer; reduced in winter
• Sick plants are not fertilized

Bonsai: how and how much to fertilize?

Since bonsai are not a fixed type of plant, but a variety of beautiful plants that fall under the collective term "bonsai" due to their cultivation method, the question of the amount of fertilizer is difficult to generalize. The following factors influence how much you should fertilize:

1. Fast-growing bonsai need more fertilizer than slow-growing ones.
2. In the summer months, more fertilizer is used than in the resting phases in the winter months.
3. If substance is to be built up, more fertilizer is used than if only the form is to be preserved.
4. In stressful situations such as heat stress, illness or after repotting, little or no fertilizer is used.
5. The older the tree, the lower the need for fertilizer, as older plants grow much more slowly than young bonsai.
6. If you want the bonsai to flower or it is already doing so, you should only fertilize a little, otherwise the bonsai could drop its flowers.
7. Bonsai with a lot of undergrowth are fertilized more.
8. Porous substrates with low organic content are fertilized more frequently and in small doses. Bonsai soils with a higher organic content can be supplied with fertilizer at longer intervals.
9. Species that require nutrients are fertilized more than frugal species.

However, one golden rule applies to every bonsai: It is better to fertilize at regular intervals with small doses, otherwise over-fertilization will quickly occur. Your bonsai reacts to this by dropping leaves or, in the worst case, even dying. So that the plant can recover from over-fertilization, you should wash the excess nutrients from the substrate or repot the bonsai in new bonsai soil. To prevent over-fertilization from occurring in the first place, it is important to follow the instructions for use of the fertilizer when fertilizing.

Summary: How (much) should you fertilize your bonsai?

• The amount of fertilizer depends on the growth, growth conditions, age and state of he alth of the bonsai, as well as the type of plant and the type and vegetation of the bonsai soil.
• Bonsai soils with a slightly higher organic content are fertilized at slightly larger intervals.
• Golden rule when fertilizing bonsai: Fertilize in small doses at regular intervals.
• If there are signs of over-fertilization, rinse the substrate or repot in fresh, high-quality bonsai soil.

The perfect bonsai fertilizer

Of course there are special bonsai fertilizers. However, these probably differ from other fertilizers mainly due to their higher price, because bonsai also need the same 14 essential nutrients as other plants. There are certainly species-specific differences, but of course no universal bonsai fertilizer can meet these either.

Fertilize bonsai organically or minerally?

Basically, the fertilization in spring should be nitrogen-rich in order to stimulate leaf sprouting. Balanced fertilization is important in summer, and in late summer and autumn a good supply of potassium is crucial, especially for garden bonsai, to ensure the necessary frost hardiness.
Then you still have the choice between organic and mineral as well as liquid and solid fertilisers. This choice is up to you and of course bonsai experts have their likes and dislikes. However, both are possible. Organic and mineral liquid fertilizers are added to the irrigation water, have to be applied at very short intervals and are available very quickly. Solid mineral fertilizers are readily available, but have an unnecessarily large ecological footprint and can quickly lead to over-fertilization if the wrong dosage is used. Solid organicFertilizers work a little slower, but longer and do not trigger over-fertilization.
The special organic fertilizer pellets can either be dissolved in the irrigation water or attached to the surface of the substrate in fertilizer baskets - the small baskets prevent them from being washed away, blown away and eaten by birds.

Our Plantura organic universal fertilizer can also be used to fertilize bonsai in summer. The Plantura organic lawn fertilizer is also perfect for the stimulating start fertilization in spring. For autumn fertilization of garden bonsai, we recommend our Potassium-rich Plantura organic autumn lawn fertilizer. Thus, the set for an animal-free and natural nutrient supply for your bonsai is already complete and only needs to be adjusted in the dosage as described above.

Tip: As a bonsai, the small-leaved lime should only be fertilized organically, as the roots are extremely sensitive to s alt.

However, natural organic fertilizers such as compost and manure are not suitable as fertilizer for your bonsai. They have to be worked into the top layer of soil every year - but this is extremely difficult with the shell culture.

Bonsai, like the azalea (Rhododendron) or the fucientee (Carmona microphylla), are sometimes known for their beautiful flowers a fertilizer with a high phosphate and potassium content, as this contributes significantly to the development of a lush flower coat. And evergreen conifers are happy about extra magnesium so that their needles stay bright green even in winter.

Summary: The Perfect Bonsai Fertilizer

• It doesn't have to be the special bonsai fertilizer
• Organic, mineral, liquid or solid fertilizers are possible
• Fertilizer pellets are attached to the surface of the substrate with a basket
• The correct fertilizer composition generally depends on the season
• Blooming bonsai need more potassium and phosphate
• Evergreen conifers benefit from a little extra magnesium

The perfect bonsai fertilizer for every season

As mentioned above, the fertilization can be adjusted to the growth of the bonsai. A distinction is made between outdoor bonsai and indoor bonsai. When budding in spring, bonsai - whether indoors or outdoors - need a nitrogen-heavy fertilizer. This way you support themFormation of leaves, shoots and buds. Deciduous trees that need to regenerate their leaves need more nitrogen than conifers. In summer, a balanced NPK ratio is used, although young and fast-growing bonsai require a higher proportion of nitrogen than old and slow-growing plants. In autumn, indoor bonsai continue to be fertilized as before, because the plants are exposed to largely constant temperatures and balanced lighting indoors. In the case of outdoor bonsai, continued nitrogen-based fertilization would not be beneficial. Instead of further promoting shoot formation with nitrogen, you should use a potassium fertilizer for autumn fertilization in August and September. In this way, shoots that have already formed harden faster and the resistance of the plant to frosty temperatures is increased. Use Patentkali for this, for example. This not only contains potassium, but also magnesium, which is important for chlorophyll formation. Anyone who swears by mineral fertilizers such as patent potash, an organic autumn fertilizer with phosphorus, potash and magnesium, can also support growth and flowering in spring. In winter, garden bonsai are not fertilized at all and indoor bonsai are only fertilized to a reduced extent.

Many thanks to Floragard for the support!

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