Japanese maple bonsai care

Care Styling Frequently asked questions

Japanese maple bonsai care

Japanese maple bonsai (Acer palmatum) are much appreciated. Without a japanese maple a bonsai collection is not complete. The colourful leaves of the different varieties (especially in autumn) and the interesting growth forms with a very fine branching are worth emphasising. When caring for the japanese maple as a bonsai, it is particularly important to note that this bonsai species likes a location in semi-shade protected from heat in midsummer.

Japanese maple bonsai care in a nutshell:


Fertilize | Watering | Location | Overwintering | Repot | Diseases, Pests | Propagation


Fertilize

Japanese maple bonsai (Acer palmatum) - Import from Japan 2018
Japanese maple bonsai - Japan import 2018

In the cultivation phase we fertilize the japanese maple prebonsai very nitrogen-rich with a mineral fertilizer (nutrient salt N-K-P ratio 4:1:2 + MgO). Thus they grow in 5l plant pots well 0.5-1m per year and develop fast. Due to the nitrogen-rich fertilization of the bonsai, trunk and branches quickly become thicker, which is desirable during cultivation. In this phase, all organic bonsai fertilizers (e. g. Biogold, Hanagokoro) as well as other garden fertilizers such as horn meal can also be given abundantly from March to September.

Although we ourselves use mineral fertilizers (with an automatic fertilizer doser for the water) we advise the layman against it. The salt tolerance of the japanese maple is not very high and calculation errors can quickly occur during dilution. Organic fertilizers (also Liquid bonsai fertilizer) have the great advantage that they are released very slowly and gently supply the bonsai tree. If you give the tree much more, nothing happens to it except that it grows too fast and too long. In addition all necessary trace nutrients are contained which the tree needs.

Japanese maple bonsai (Acer palmatum) - Import from Japan 2019
Japanese maple bonsai - Japan import 2019

When it comes to the fine styling of a Japanese maple bonsai we must pay more attention to a balanced fertilization with not too high nitrogen loads. If too much nitrogen is given, the internodes (the distance between 2 nodes on a shoot) are too long. If too much nitrogen is given too long in the year then the Japanese maple bonsai can not cure properly before hibernation. Not properly cured young shoots then freeze in the winter sometimes back a bit. This is not a problem in the growing phase, with a finished bonsai it would be very regrettable. Just this fine branching distinguishes this bonsai species.

Finished bonsai can also be supplied well with a commercial bonsai liquid fertilizer. For finished maple bonsai it is recommended to follow the dosage instructions on the bottles. Liquid bonsai fertilizers usually do not contain much more than 3% nitrogen. Just fitting for a Japanese maple.

In winter and 4 weeks after repotting a bonsai is not fertilized. The Japanese maple can not use the fertilizer in both cases.

Watering

Japanese maple bonsai (Acer palmatum) on an exhibition
Japanese maple bonsai on an exhibition

Acer palmatum bonsai loves it evenly moist. The emphasis is on evenly, that means do not let it dry out and on the other side - do not drown. It is good to let the soil dry off occasionally before pouring a bonsai tree (do not let the bale dry out). Even in winter you should not let the japanese maple dry out completely (use in winter a period of frost-free weather for pouring).

It is important that the bonsai soil well permeable to water and air so it does not come to waterlogging. If the soil is well drained, it can be watered several times on hot summer days. The excess water can drain well.

The fine leaves evaporate in midsummer plenty of water. Often more than the bonsai pot can deliver and more than you can pour under normal conditions. This can cause it to come to dry leaf tips. Therefore, it is advisable to place a japanese maple bonsai in summer in a partially shaded and sheltered place.

Location

In summer, a sunny to partially shaded outdoor space is suitable. Fine-leaved varieties should get no midday sun in midsummer (otherwise the japanese maple bonsai gets brown leaf tips). Partial shade is well suited for japanese maple bonsai. But the leaf coloration of many reddish varieties becomes a bit greener in the shade as the tree forms more chlorophyll here, which makes it greener.

Japanese maple bonsai (Acer palmatum) - Young plants in autumn colors
Japanese maple - autumn colors

Overwintering

The Japanese maple is a winter hardy outdoor bonsai, that means it tolerates temperatures below 0°C well. There should be a windbreak to prevent the fine branches from drying out (for example, an unheated greenhouse, a foil tent or a sheltered outdoor corner). In frost-free weather, check the soil for moisture and pour if necessary.

Repot

Repot with commercial bonsai soil (for example Akadama). A young Japanese maple bonsai is repotted every 2-3 years, older specimens every 4-5 years (if growth decreases or in case of root diseases possibly more often). A drainage layer at the bottom of the pot is beneficial.

In any case, the bonsai soil should be well drained so that during the frequent watering in midsummer it does not come to waterlogging. For this the Japanese bonsai soil Akadama is well suited. Experienced bonsai friends even sieves the dust out to increase the permeability. The dust may be used to cover the surface. The permeability can also be increased well by adding bonsai substrates such as expanded slate. Since a Japanese maple prefers slightly acidic soils, the bonsai soil should not be too calcareous.

The repotting of bonsai takes place in early spring (end of February). Depending on the rooting a more or less strong root cut is made. If it is repotted too late, the maple may "bleed" for a longer time after repotting. That is not optimal. Therefore - do not pot too late. And if desired, rather moderately cut back the roots.

The Japanese maple has a shallow root system. It is therefore suitable for very shallow bowls.

Diseases, Pests

The Japanese maple is sometimes visited by aphids. In case of mass infestation, simply spray with an insect repellent agent. Aphids are not a big problem.

Rarely caterpillars or beetles eat on the leaves. But they can be collected well.

Rather important is the susceptibility of the Japanese maple for fungi (Verticillium). Does not happen too often, but is dangerous for a Japanese maple bonsai. Watch for sudden appearance of flaccid leaves or the sudden death of entire branches.

Since a treatment with fungicides is almost impossible, should be well prevented. For this it is important to only trim Japanese maple bonsai with clean bonsai tools. Also with root cuts. When potting (for root cutting) you should use an old bonsai scissors as this is dull quickly and then no longer suitable for pruning bonsai. Sealing the cuts with wound sealant can reduce the likelihood of infestation.

Propagation

Acer palmatum can be propagated by tree seeds or cuttings. But Japanese maples are genetically very variable and propagating seeds leads to bad results. It is better to buy a suitable young plant.

Sometimes a Japanese maple from the garden (or a branch of it) can be propagated by air-layering. It's a good way to get raw material quickly and works well with the Japanese maple.

Japanese maple bonsai styling

The Japanese Maple is very popular for bonsai styling. By regularly cutting and pinching the bonsai tree you can build a very finely branched crown. The strong root growth can be used to make beautiful root approaches. And the very small, often strikingly colored leaves are very decorative. Especially in the fall.

Japanese maple bonsai styling in a nutshell:

  • Wiring: Wire carefully. The thin bark can be injured quickly. Slowly and carefully bend. Branches are hard and quite brittle.
  • Pruning: In early spring do not cut large branches too late. Otherwise Japanese maple "bleed" for a long time. For a fine branching you should pincing regularly.


Wiring | Pruning | Styles | Bonsai pots | Flowers, Fruits | Bark, Roots | Varieties | General


Wiring

Woody, thin branches can be easily wired. The thicker branches are stiff (branch should be protected from constriction of the bark by leather or rubber). If you want to wire a bonsai - please work careful. The bark is very thin and easily damaged by mechanical action. Such injuries are seen on the smooth bark very long.

Aluminum bonsai wire is preferable. The required diameter is larger than copper and so the wire presses not so much on the bark. Possibly the wire can still be wrapped with paper for protection.

Pruning

The maple can be shaped very well as bonsai by pruning. The maintenance pruning, structural cutting and pincing of the bonsai tree comes into play.

Maintenance pruning: In spring, when the maple has formed about 5 pairs of leaves, these are cut back to one or two leaf pairs. Do not cut before budding (severe bleeding and resulting tree damage).

Pincing: The shoot following after pruning should be pinced. That means newly formed shoot tips are removed after the first pair of leaves. A fine branching of the branches is the reward for this laborious work.

Structural cutting: Once a year, dead branches as well as branches not needed for the design are removed. Cut such branches with a sharp bonsai concave cutter direktly on the bark. The structural cut can be done in early autumn or at the end of the winter.

In order to control the growth force within the tree, a partial defoliation can also be carried out in the summer. For this purpose many or all leaves are removed on strong parts of the tree and on weaker branches only some. This reduces the vigor of the thicker branches, promotes fine branching (shorter internodes) and reduces leaf size. Above all, weaker branches can gain strength. In the case of red-leaved varieties, the leaf cut should be somewhat more restrained.

Wound sealant should be applied especially for larger cuts to better protect the maple from infestation with fungi.

Styles

The Japanese maple can be designed as an informal upright bonsai, as a multiple trunk and raft form as well as a Root over rock bonsai style. The variety Acer palmatum Kiyohime is extremely suitable for the Broom bonsai style.

Matching bonsai pots

For Japanese maple bonsai with their often colorful leaves glazed bonsai pots are best suited. Since Japanese maple belong to the hardy outdoor bonsai should be selected as possible frost-resistant, handmade bonsai pots. The inexpensive bonsai pots (made for indoor bonsai) are in our experience almost 100% frost resistant. However, we do not guarantee frost resistance with these pots.

Japanese maple bonsai (Acer palmatum) - Sorten Katsura + Atropurpureum
Japanese maple bonsai Katsura + Atropurpureum

Unglazed bonsai pots are usually less suitable. If unglazed then the color should be light (for example gray). For large japanese bonsai you will find suitable pots under Large bonsai pots.

Japanese maple bonsai with its roundish crown fit very well into an . Rectangular bonsai pots are usually not suitable. If it's supposed to be a rectangular bonsai pot then we'd pick a pot that has some rounded corners. Flat, round bonsai pots are sometimes also suitable. Especially as Japanese maple bonsai often have a very flat root ball. Drip trays for bonsai pots are not needed because a Japanese maple should not be maintained in the apartment.

Suitable pots for Prebonsai in the growing phase are the plastic bonsai pots. The dark brown color of the pots does not go so well with the often gray stem of a Japanese maple bonsai. But these plastic pots are absolutely frost-resistant, UV-stable and much cheaper than a ceramic pot. For 2-3 year old seedlings in cultivation, it is best to take plastic plant pots.

Flowers, Fruits

The greenish, sometimes red flowers are rather inconspicuous and appear in May-June. But they are not too common on bonsai trees. Most trees are probably still too young for flowering.

The fruits formed from the flowers are more important. They are decorative and are recognized by every child as typical maple seeds.

Bark, Roots

The bark of young maple bonsai is green and red in some varieties. Over time, the bark turns gray or light brown. It is very thin and especially when you want to wire a bonsai care must be taken not to damage them.

Varieties

There are a plethora of varieties from the Japanese maple. It is not possible to enumerate even a part here. We limit ourselves to varieties that are well-suited to bonsai design and, above all, are more frequently available on the market.

Japanese maple bonsai (Acer palmatum) - Sorten Arakawa und Kiyohime
Japanese maple bonsai Arakawa und Kiyohime

Which Japanese maple varieties are suitable as bonsai ?

  • Acer palmatum Arakawa: Cork bark maple. Very barky bark. Unfortunately rare in recent years
  • Acer palmatum atropurpureum: Dark red leaves, even in summer
  • Acer palmatum Deshojo: Dark crimson buds and young leaves in spring, green leaves in summer. This variety is frequently offered
  • Acer palmatum Katsura: Orange young leaves in spring and orange autumn color. Green in summer
  • Acer palmatum Kiyohime: Extremely fine branching. Very suitable for the broom shape. Here is the term dwarf tree appropriate. This variety is usually very small
  • Acer palmatum Seigen: Red leaves, finely pinnate, rarely seen
  • Acer palmatum Shishigashira: Slow growing. The leaves are very wavy, the shoots are short but strong. From time to time to see as a bonsai tree

Japanese maple bonsai need some shade in midsummer. Red-leaved varieties tends to grow more green in the shade because they produce more chlorophyll.

General

The Japanese maple (Acer palmatum) is native to Japan, China and Korea. It is, depending on the variety, a mostly small tree of 2-6m height, rarely more. Palmatum means "hand-shaped" which indicates to the mostly 5-lobed leaves.

In recent years, the import of maple bonsai from Japan, Korea and China has become more difficult. This has unfortunately led to the situation that such Bonsai rare to see and buy.

Frequently asked questions

My Japanese maple bonsai has dry leaf tips. What should I do ?

  • Place a Japanese maple bonsai in the semi-shade in summer. It does not like dry heat
  • Check on hot summer days several times, whether the bonsai soil is still wet
  • If necessary, pour a bonsai several times in midsummer. Especially on windy days
  • Next spring, repot the bonsai tree into a well-drained substrate, e.g. Akadama bonsai soil