Chinese elm bonsai care
Chinese elm bonsai care
The Chinese elm (Ulmus parvifolia) is an extremely robust tree species very suitable for bonsai design. It tolerates a wide range of different conditions (temperature, light, humidity) and is therefore a popular bonsai tree. It is suitable for care as a indoor bonsai as well as an semi-outdoor bonsai. Due to its high cut compatibility, it is 1st choice for a bonsai beginner. On a Chinese elm you can practice well techniques for more sensitive bonsai species.
Chinese elm bonsai care in a nutshell:
- Fertilisation: Fertilize from March to September with an organic bonsai fertilizer such as Biogold, Hanagokoro or Bonsai liquid fertilizer
- Irrigation: Water a lot in summer, especially if your Chinese elm bonsai is held outdoors. Keep moderately moist in winter
- Overwintering: Can be overwintered in a cool and very bright room as an indoor bonsai or cold like a mediteranean bonsai in a foil tent or greenhouse
- Repotting: Repot every 3-4 years at the beginning of March in a well-drained bonsai soil like Akadama. When repotting, the strongly growing roots should be cut back
Diseases, Pests |
⧉ Chinese elm bonsai (Shouzou, China)
Fertilize your Chinese elm bonsai during the growing season, ie. from spring to autumn. For finished bonsai you can use liquid bonsai fertilizers in the amount recommended on the package. In young prebonsai (where strong growth is desired) you can also give twice as much. For organic solid fertilizers (like Biogold or Hanagokoro), one application will suffice every 1-2 months. It should be noted that these bonsai fertilizers take a while to become effective. That means you can give the first pellets as early as 1 month before the start of growth. The advantage of this solid fertilizers is: their effect is more even and long-lasting.
A Chinese elm bonsai does not like it too wet or too dry. Once the substrate surface has dried slightly, it should be poured. Waterlogging and root ball dryness should be avoided if possible
If the Chinese elm is maintained as an indoor bonsai, the problem exists that water drips through the water drainage holes onto the window sill and pollutes it. With a bonsai pot drip tray (is supplied in many cases with indoor bonsai directly) this can be avoided easily. In our experience, a ball shower is well suited for pouring an indoor bonsai.
⧉ Chinese elm prebonsai (China)
The Chinese elm can be cared for as an indoor bonsai or as a semi outdoor. In both cases it is best to place a Chinese elm in summer in full sun. In mid of summer with high temperatures a partially shaded place is better because the bonsai pots get very hot in the sun. The chinese elm tolerates the heat in midsummer but grows better in partial shade.
In winter a Chinese elm bonsai (if maintained in the appartement) should be placed very bright. As bright as possible, directly on the window. A place in the apartment should also be as cool as possible. Bright place = High photosynthesis rate, Cool = Low metabolism. Under these conditions, this bonsai species feels comfortable in the apartment and usually retains all its leaves.
It is even better to cultivate the Chinese elm in winter as a semi outddor bonsai. Best in an unheated greenhouse or foil tent. There it has no problem with slight minus temperatures (down to -5°C, we have no problems observed). The tree simply drops the leaves like other deciduous trees and goes into hibernation. A chinese elm will be sprout out stronger next spring after such a winter break.
It is also important to have enough air movement. Under high humidity conditions (like in a greenhouse in summer) leaves inside the crown may be attacked by mold. While this is not threatening it should be avoided. Simply ventilate regularly or place it in the summer right outside.
In summary: Open air place in summer, Half-shade in mid-summer, in winter a very bright and cool to cold position.
Chinese elm bonsai tolerate very good freezing temperatures. According to our own experience, temperatures of -5°C in an unheated foil tent are not a problem. There are even studies from America where planted trees survive far lower temperatures. If possible, you should therefore winter this tree cold.
Hibernation in the apartment is possible. But even here the tree location should be as cool as possible. But especially bright. As bright as possible. A warm, dark cellar is not suitable. Rather a window place in the unheated garage or in the cool staircase.
Chinese elms have a strong root growth. Therefore, fast-growing, younger specimens are repotted every 2 years, older every three to five years. The best time is early spring (end of February). In each case a root cut should be made. Since elm tree bonsai have very soft roots, a very sharp concave pliers are required for root incision. For roots up to 1cm in diameter a sharp bonsai scissor is very helpful. Blunt bonsai tools leads to bruising of all elm species during root cutting. These wounds heals bad.
On the Internet there are numerous recommendations for special soil mixtures for elms bonsai. In our experience, it is especially important that the bonsai soil is well permeable to water and especially air. The root cells, like all cells, need oxygen. If the soil is too fine it quickly lacks oxygen. Be sure to pot your bonsai in a well-drained soil. The Akadama bonsai soil imported from Japan meets these conditions very well. Other soil mixtures may also be well suited. But why should we invent the wheel twice? Akadama has everything a bonsai soil for Chinese elms needs.
A bonsai of Chinese elm is not very susceptible to pests and diseases. When fertilized with nitrogen, insects or spider mites are sometimes infested. Both pests can be well controlled by commercial means.
If Chinese elms are kept too moist and dark (with little air movement), the leaves can be infected with mold fungi. We sometimes see this when unloading an import container (the trees need 6 weeks in the dark and wet container from China to us). The mold fungi are not a problem. If the leaves of the import trees are moldy, they are cleaned with a high pressure cleaner and after that the trees are placed in a suitable location. After 1-2 weeks, the new shoots sprouts out as if nothing had happened.
Elm disease - elm dying: A Chinese elm bonsai is usually never infested. The trunks are not thick enough for the elm beetle (carrier of elm disease).
In summary: In Winter - bright location, as cool as possible, in summer an outdoor place if possible = healthy bonsai. If it always comes back to pest infestation the location is not right. Usually too dark.
The Chinese elm can be propagated by seeds. The seed must be stratified in Winter and sown in spring. However, since stratification (= Cold treatment of the seeds to simulate natural conditions) of tree seeds is not so easy, we advise against it.
The propagation by cuttings is simple. It is best to cut off a thin, already woody shoot in late spring, let it dry slightly for 1-2 hours and then put it into the soil. When the soil temperature and humidity are high new roots will form within a few weeks.
If stronger roots have to be removed when repotting, the Chinese elm can be propagated via root cuttings. This is even better than with normal cuttings. With thick roots the success is almost 100%.
But if you do not want to design / style your elm bonsai from scratch, we recommend to buy a bonsai in a shop. Chinese elms are available everywhere and cost very little. You will save a lot of time if you buy the appropriate plant.
Chinese elm bonsai styling
The Chinese elm is one of the most common species that is formed as bonsai. It is very popular and is particularly suitable for bonsai because of its small leaves. The leaves are up to 5cm long in nature. On a bonsai with strong branching they are often only 1cm tall, sometimes even smaller. Very suitable also for very small Bonsai. In addition, it branches out very strongly and finely. With good care you have already after 1-2 years a very dense crown with many, fine shoots.
Chinese elm bonsai styling in a nutshell:
- Wiring: The bonsai wire can be applicated easily because the flexible branches are not very sensitive
- Pruning: Cut back vigorously with sharp bonsai scissors 2-3 times from May to early August
Bonsai pots |
Flowers, Fruits |
Bark, Roots |
A well pre-designed Chinese elm can only be kept in good shape with a cut. But by wiring the branches you can much better influence the shape and quality of the bonsai.
If you want to wire this type of tree, it is best to keep it cold in autumn so that the leaves are thrown off. This makes it much easier to attach the bonsai wire. The elm thrown off its leaves at the latest after the first night frost.
Only already woody shoots are wired. But with the Chinese elm this happens very quickly. A shoot already lignifies after 1-2 months. One- and two-year-old shoots and branches are still easy to wire and bend into shape. The wire is wrapped around the branch at an angle of 45° and then the shoot is bent into the desired position. Stronger branches are most gently stretched with thin wire into the new shape, otherwise the bonsai wire would leave traces in the bark too quickly.
The young shoots are best grown up to a length of 10cm and then cut back to 1-2 leaves. By "let it grow" you get a good increase in thickness. In the case of older, already well developed branches, only a regular pruning to the desired shape is carried out.
Chinese elms grow very fast under good conditions. 10-15cm a month are not unusual, sometimes more. In order to keep the bonsai with such a stormy growth in shape it has to be cut back about 3 times a year. We cut our Chinese elms around mid-May, late June and mid-August. Then the growth slows down and we often don't cut until spring.
When the Chinese elm is kept cold in winter, it usually sheds all its leaves. Then you can see the branch structure particularly well and, if necessary and desired, you can also cut back the shoots in winter.
⧉ Chinese elm bonsai pruning
When cutting a Chinese elm you need a particularly sharp bonsai scissor. The wood of this tree is very soft. If the scissors are not very sharp they bruise the shoots when pruning. Besides, it works much better.
If larger branches are removed, it is good to cover the wounds with bonsai wound sealant. The wounds heal better and faster.
None of the known styles are impossible. The broom shape and the freely upright shape can be designed very well.
A rock form is, due to the strong root growth of the Chinese elm, also well to realize. Here, however, the strong growth of the roots has to be considered. If the stone is too small, you won't see it after a few years. The roots will overgrown the stone.
Matching bonsai pots
Glazed bonsai pots are suitable for Chinese elm bonsai. Since this elm species does not belong to the absolutely hardy outdoor bonsai, you only need to take a frost-resistant, hand-made bonsai pot when you place the bonsai trees during winter in an unheated foil tent or greenhouse. The inexpensive bonsai pots for indoor bonsai are sufficient for overwintering Chinese elm tree bonsai indoor. Although it has to be pointed out that the quality of these inexpensive pots cannot keep up with the handmade bonsai pots.
Unglazed bonsai pots are less suitable. If an unglazed bowl is being considered then it is best to choose one of the handcrafted bonsai pots. The range of different clay colors is much larger here. Suitable pots for large bonsai can be found under Large bonsai pots.
Chinese elm bonsai with their rounded crown fit very well in an oval bonsai pot. Rectangular bonsai pots are particularly suitable if these pots have slightly rounded corners. Higher, round bonsai pots (or square ones) are particularly suitable for bonsai in semi-cascade or cascade style. Flat, round pots are fine for the literary bonsai style. However, this doesn't really work good with the Chinese elm.
Plastic bonsai pots are suitable pots for prebonsai in the growing phase. The dark brown color of the pots goes well with the dark trunk of the Chinese elm. The plastic pots are impact-resistant, UV-stable and very cheap. For 2-3 year old cuttings to be grown, it is best to use plastic plant pots.
Flowers and fruits get the Chinese Elm from an age of about 15 years. The inconspicuous flowers are not important for the bonsai design. The flat, oval to round fruits (they are called Samara, diameter approx. 1cm) already stand out a little more. But they are also not very important for bonsai design.
The roots of the Chinese elm are very soft and fleshy. Since the roots grow very quickly, a stronger root cut must be carried out regularly when repotting in order to achieve a fine branching of the roots. If the proportion of fine roots is high, bonsai can absorb water and nutrients much better.
The predominantly grey bark of the Chinese elm is smooth in younger trees. In older trees, flat bark plates form. Although the wound healing is good, larger cuts remain visible for some time on the smooth bark. Therefore, it is good not to leave branches and shoots on the tree for too long. If a larger branch needs to be removed, a bonsai wound sealant should be applied to the cut. This significantly improves wound healing.
There are both slow-growing varieties of the Chinese elm and, for bonsai design very attractive, varieties with coarse bark. unfortunately, such varieties are rarely available.
The Chinese elm (Ulmus parvifolia) is a deciduous deciduous tree from East Asia. It occurs in nature eg. in China, Japan and Korea and is usually not higher than 15m. They can even be found in some botanical gardens in Europe. This means that the Chinese elm can withstand the climate in some parts of Europe even in winter. Ulmus parvifolia is often referred to as Zelkova. That's not correct. The Zelkova also belong to the elm family, but to another genus.
Chinese elm bonsai - Pictures
Bonsai - Frequently asked questions (FAQ)
What to do if my Chinese elm bonsai has aphids ?
In order to keep the Chinese elm healthy, prevention through a suitable location is important. If a Bonsai of the Chinese elm is kept too dark in the apartment, it sometimes comes to the infestation with aphids. In most cases, this can already be avoided by switching to a better location.
An example: A customer brought us a Chinese elm bonsai with a request for help. It was May and the bonsai looked regrettable. Long, thin, almost leafless shoots with lots of aphids. We took the bonsai to take care. We simply put him outside to our other Chinese elms. After approx. 1 week I wanted to take care of the tree (spraying against aphids and cut back). And I was very surprised. There was no more aphid on the tree. But all the more larvae from the ladybug. And the first strong buds already appeared. After pruning and without the use of pesticides, the tree looked great after 3 weeks and already had new, 4-5cm long shoots. The customer was satisfied and must have thought it was magic.
What to do if my Chinese elm bonsai has yellow leaves ?
Chinese elm bonsai need a lot of light. Especially if they are wintered in the apartment. The Chinese elms often suffer from lack of light in the darker winter months. If a China Elm gets yellow leaves it is almost always due to lack of light.
Lack of light occurs mainly after the purchase (Bright greenhouse -> Much darker apartment) and in winter, when the days are short and dark. Choose the brightest place in the apartment and place it there. The south side would be best, right by the window.
Sometimes (in winter) it can take a few weeks for the tree to get new leaves. Don't worry about that. Especially not in winter. Simply place on a bright place, water moderately and do not fertilize or repot until the leaves sprout again.