Fertiliser

Once in the pot, the nutritional content of the soil on its own is often not able to satisfy bonsai requirements to grow strong and healthy trees. For this very reason, bonsai enthusiasts regularly use organic or inorganic fertilisers, liquid or solid, pre-made or personally mixed depending on their preferences.

Your bonsai will need seventeen very important nutrients, which are divided into macronutrients and micronutrients. The nutrients include calcium, magnesium, zinc, and iron, to name a few, and they will be absorbed by the tree through the soil.

While the micronutrients are required in very small quantities (one part per million), and trace elements of the most important are usually contained in fertiliser products, the macronutrients are the ones that we are after. Specifically, we’re looking for nitrogen, phosphorous, and potassium. These are often highlighted on fertiliser packaging as NPK with their quantity (for example, N-P-K 4-5-4). These three macronutrients are responsible for the vigour of the tree, the colour of the leaves, the health of the roots, and the fruit and flower production, along with resistance to diseases.

It is important to choose a well-balanced fertiliser that is not too high or too low in these nutrients. Overfeeding may burn the root system or unbalance the growth of the tree and leaves, which we aim to keep at a certain size. Alternatively, there may be enough to keep the tree healthy because it will not be able to withstand the poor nutritional environment.

I personally use liquid fertiliser from spring until the end of summer and then apply solid pellets in autumn and, in some cases, winter. I look for the following proportions depending on my trees’ needs, the season, and the specimen:

  • N-P-K 6-3-6
  • N-P-K 4-5-4
  • N-P-K 5-3-5.

The feeding period commences with the start of the growing season (the end of March), and I feed at regular intervals of at least once every two weeks. The gap increases to once a month in autumn, and then I stop feeding in the winter when the tree starts its dormancy phase (except for indoor bonsai, which I continue to feed).

I hope that this guide for feeding frequency, timing, and portion gives you a starting point to approach this task. Along the way, you will make your own adjustments and improvements to suit your trees.

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Wisteria

Family: Fabaceae

Genus: Wisteria

Botanical Name: Wisteria floribunda

Wisteria is an elegant and colourful woody climbing deciduous specimen with alternate dark-green pinnate-like leaves. It produces clusters of flowers in white, pink, purple, or violet depending on its cultivar. The Wisteria floribunda, also known as Japanese Wisteria, and the Wisteria sinensis (Chinese Wisteria) are both very popular with bonsai enthusiasts.

wisteria media

Style

Because the main feature of this tree is the cascading, clustered flowers, any style that accentuates this characteristic, such as informal upright, slanting, semi-cascade, and cascade, will most likely the best display choice.

Location and Position

A full, hardy tree such as Wisteria should be kept outdoors all year round in full sun exposition. But because we will move it to a pot and not on the ground, a little protection during winter, such as being placed under a bench, could be a safe choice.

Watering

This is a very thirsty plant that requires a great amount of watering from spring to summer. In autumn and winter, you can go back to the rule of keeping the soil moist but not soaking wet.

Feeding

This plant has very strong growing habits which require some support in terms of feeding. It is also important to know that Wisteria can produce nitrogen on its own. To allow it to flower regularly, use fertiliser without nitrogen or a very small quantity only.

Pruning and Pinching

Maintenance pinching is best carried out after the tree has flowered while structural pruning is easier during autumn. Pay attention not to remove flower buds.

Repotting and Soil

Repot in early spring every other year in a well-drained soil mix, such as two parts akadama and one part pumice

Wiring

Wiring is best carried out when the Wisteria loses its leaves in autumn

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Ginkgo

Family: Ginkgoaceae

Genus: Ginkgo

Botanical Name: Ginkgo Biloba

Commonly known for its dietary benefits, the Ginkgo biloba, along with the dawn redwood, is a living fossil specimen native to China. The Gingko offers a light-grey fissured bark and can produce areal roots, helping this tree to extend its longevity. It is a deciduous plant with alternating clusters of fan-shaped leaves that turn a beautiful yellowish colour in autumn before falling.

Ginkgo media

Style

Another similarity to the dawn redwood for the Ginkgo is the ability to grow quite high, making it suitable for formal or informal upright styles. But it can also be shaped in many other styles, such as slanting, forest, or cascading.

Location and Position

The Ginkgo biloba is to be kept outdoors all year round in a full-sun position. In winter, a little protection by placing it under a bench can be given when the temperature falls below zero to protect the rooting system. Once the tree is relocated in a pot, it will lose a bit of its hardiness against cold temperatures.

Watering

This tree requires a moist, well-drained environment. Do not let the Ginkgo become bone-dry or to be soaking wet; otherwise, the rooting system will suffer, and the tree may perish in the worst-case scenario.

Feeding

From growing season to autumn, I prefer to fertilise the Ginkgo biloba with an organic liquid fertiliser and then apply solid organic pellets once to cope with winter necessities.

Pruning and Pinching

For maintenance, pinch back new growth to two or three nodes once it is fully extended. Structural pruning is best carried in autumn because the foliage will have fallen, and the structure of the tree will be clearer.

Repotting and Soil

The Ginkgo can be repotted every one to two years (especially when it’s still young) or as soon the roots fill the pot in early spring. Use a well-drained bonsai soil mix.

Wiring

Autumn appears to be the best time to wire the Ginkgo because you can easily go through the tree, which will have no leaves, offering better visibility for branch placement

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Dawn Redwood

Family: Cupressaceae

Genus: Metasequoia

Botanical Name: Metasequoia glyptostroboides

Metasequoia glyptostroboides, also known as dawn redwood, is a deciduous conifer specimen with an amazing reddish-coloured bark and bright-green needles. It was believed to be extinct until a living specimen was discovered in China and then exported worldwide to repopulate the globe with this magnificent tree.

small redwood media

Style

This tree has strong growing habits. In fact, it can grow very tall in nature, making this tree ideal for upright styles. However, it can be trained in other styles, such as forest and slanting, to name a few.

Location and Position

The Dawn Redwood enjoys full sun and appreciates some semi-shade on very hot days. Once in a pot, the tree will be grateful to receive a little frost protection during the winter.

Watering

Intolerant of droughts, the Metasequoia glyptostroboides requires moist soil. To avoid root rot, don’t allow the soil to be soaking wet

Feeding

Feed with a liquid fertiliser every two weeks from spring until late summer.

Pruning and Pinching

Structural pruning is best carried out during the fall because the branch structures will be more visible once the tree loses its foliage. Pinching back new shoots should be attempt during the growing season to maintain the bonsai’s shape.

Repotting and Soil

Repot the dawn redwood every other year or as soon as the roots fill the pot—ideally before the buds swell—in a well-drained soil mix. One part akadama and one part pumice (with bark mulch if extra retention is needed) should do the job.

Wiring

Fall seems to be the best time to wire the Metasequoia glyptostroboides because the tree will be free of foliage, allowing for better visibility for branch placement. Growth slows in the fall as well, so the risk of scars is lower.

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Ilex Crenata

Family: Aquifoliales

Genus: Ilex

Botanical name: Ilex crenata

Evergreen or deciduous, the Ilex genus belongs to the Aquifoliales family, which has over four hundred species. Native to Japan, China, and Korea, the Ilex crenata (also known as Japanese holly) is an evergreen specimen with glossy alternate dark-green leaves. It produces small white flowers and black drupe fruits. Its small, dense, spiny foliage makes the Ilex crenata a desirable material for bonsai enthusiasts.

Ilex media

Style

Commonly displayed in formal and informal upright or broom styles, is worth mentioning that Japanese holly can be trained in most bonsai styles.

Location and Position

This plant can be kept outdoors all year round, with full sun exposition in the spring and semi-shade in the summer. It’s naturally a very sturdy tree, but if placed in a pot, it will benefit from a little protection, such as being placed under a bench when the temperatures drop below zero.

Watering

Ilex crenata appreciates moist soil. Don’t let the soil dry out or become soaking wet for long periods of time, or the tree will suffer and eventually die.

Feeding

Feed Japanese holly with liquid fertiliser every two weeks during the growing season and feed once with solid slow-release pellets in the fall.

Pruning and Pinching

During the growing season, allow the new shoots to elongate, and then pinch them back to two or three leaves. Structural pruning is best carried out from early summer to mid-fall.

Repotting and Soil

Repot every two years or when the roots fill the pot. Repot in the spring with a well-drained soil mix, such as one part Akadama and one part Pumice

Wiring

Ilex crenata’s branches are very brittle, which means that wiring requires close attention so you don’t snap them. I prefer to wire in the mid-summer to fall.

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