Cultivation, care and secrets of the Chinese elm (Ulmus parvifolia) as a bonsai and in the garden

Introduction to Chinese Elm (Ulmus parvifolia)

The Chinese Elm, botanically known as Ulmus parvifolia, is a species belonging to the Ulmaceae family and native to Southeast Asia. It's prized in the bonsai world for its small leaves, fine branching capacity, and its resilience, adaptability, and rapid growth. For all these reasons, it's considered one of the most recommended options for both beginners and advanced enthusiasts looking for an elegant and versatile tree.

The Chinese Elm is a semi-evergreen tree, which means it can retain its leaves in temperate climates and only lose them in cold winters. Its popularity has transcended bonsai, as in gardening it also stands out for its decorative bark, dense branching, and resistance to many diseases common to other elms.

Although it officially belongs to the genus ulmus, is sometimes mistakenly called Zelkova parvifolia due to its resemblance to this genus. This confusion is due to the alternate leaves and growth habit, although the botanical identification Correct cutting is simple thanks to the characteristic double teeth of its leaves, as opposed to the simple teeth of the Zelkova.

Origin and botanical characteristics of the Chinese Elm

The Chinese elm is native to Southeast Asia., predominant in countries such as China, Korea, and Japan. In its natural habitat, it can reach 20 to 25 meters in height, developing a robust trunk up to 1 meter in diameter in long-lived specimens. In cultivation, especially as a bonsai, it stands out for its compact growth and its ability to branch densely.

• LeavesSmall, oval, alternate, with doubly toothed margins and pronounced venation. Their color is deep green in spring and summer, turning yellow, orange, or reddish in autumn.
• Trunk and bark: The Young specimens have smooth, greyish bark, which becomes scaly and decorative with maturity, showing layers of various shades.
• Flowering and fruitsIts flowers are tiny, inconspicuous, whitish, greenish, or reddish, and may appear before the leaves. The fruit is a flattened, circular samara that dries and disperses easily in the wind.
• Leaf habitsIt is semi-evergreen in temperate conditions and deciduous in colder climates. It is highly adaptable to different climatic conditions.

Natural habitat and distribution

The Chinese Elm thrives naturally in temperate zones The Northern Hemisphere and, to a lesser extent, tropical and subtropical zones. It is especially abundant in plains, riverbanks, and areas with fertile, well-drained soils. Its ecological diversity allows it to tolerate everything from cold winters with frost to hot, dry summers, facilitating its cultivation in multiple regions of the world.

In gardening and landscaping, this species is used both as a shade tree and in urban alignments, thanks to its resistance and low susceptibility to graphiosis, a disease fatal to other elms. As a bonsai, it is celebrated for its tolerance to shaping and its ability to adapt to both outdoor and indoor use in bright locations.

Identification and differences with other elm species

The gender ulmus It comprises a variety of species, many of which are cultivated or naturalized outside their native range. Among the best-known are:

• Ulmus minor (black elm): native to Europe and western Asia.
• american ulmus (American elm): native to North America.
• ulmus laevis (trembling elm): typical of Asia and Eastern Europe.
• ulmus glabra (mountain elm): widespread throughout Eurasia.
• ulmus pumila (Siberian elm): very resistant to drought.
• Various hybrids and regional species (Japanese, English, Dutch, etc.).

La Main difference between Chinese elm and other elms Its distinctive features are its leaf size, the double serrations on its margin, and its scaly bark with age. Compared to the Zelkova, the Chinese elm has smaller, less rough leaves. You can find more information about Ulmus glabra in this guide..

Preliminary considerations before growing a Chinese elm

Before starting to grow a Ulmus parvifolia It is important to consider:

• Availability of light and spaceThe Chinese elm requires plenty of light, with full sun exposure being ideal. It can be grown in pots or directly in the ground.
• Regional climate: It tolerates moderate frosts and also warm periods, showing great flexibility.
• Soil type: It prefers slightly acidic (slightly calcareous) and well-draining soils, avoiding waterlogging.
• Access to quality water: Although it is hardy, it thrives best with low-limescale, well-dosed water.
• Handling and modelling: Its ability to sprout well from old wood makes it an ideal candidate for extreme shaping and creating unique styles.

Suitable location for Chinese elm (Ulmus parvifolia)

The ideal location for the Chinese elm is outdoors in full sun year-round., promoting healthy growth and vigorous foliage. Whenever possible, it should be placed in a location that receives maximum sunlight, especially during the period of active growth.

• Protection in winterAlthough it tolerates cold, it is advisable to protect it from severe frost and icy winds, especially if grown in a pot. A cool greenhouse or sheltered space is suitable, avoiding heated environments that can stimulate unseasonal winter budding.
• Indoor only in very bright situations: It can be grown indoors, but only when the environment is very bright and well-ventilated. Under these conditions, the Chinese elm can perform as a semi-evergreen and maintain its attractiveness year-round.
• Temperate and extreme climatesIn regions with mild winters, the Chinese elm rarely loses its leaves. In colder areas, it may go dormant and become deciduous.

It is crucial to avoid proximity to artificial heat sources and dry environments that can favor pests such as red spider mites or mealybugs.

Proper watering of Chinese elm

Irrigation is an essential aspect in the successful cultivation of Chinese elm.This species appreciates constant but well-managed humidity, avoiding waterlogging.

• Frequency and method: Watering is recommended when the surface layer of the substrate begins to dry outWatering should be deep, ensuring that water runs out through the drainage holes.
• Water quality: Prefers soft or low-calcium water. Highly calcareous water can promote chlorosis (yellowing of leaves). Hardy bonsai also require proper watering, as described in this link.
• Times of greatest needIn summer and during periods of active growth, the Chinese elm requires more water, while in winter or during periods of dormancy it considerably reduces its consumption.
• Avoid excess moisture:Waterlogging is dangerous for the root system, as it encourages the growth of fungi and root rot.
• Nebulization: Indoors or in dry environments, it may benefit from a light spray, although excessive spraying encourages fungi and disproportionate foliage growth.
• Do not water after frostIf the tree has experienced frost, it is best to wait for the substrate to return to room temperature before watering, avoiding frost damage to the roots.

Fertilizing Chinese Elm: Times and Methods

Regular fertilization ensures healthy growth and dense foliage in the Chinese elm.Your fertilization program should be adapted to the growth phases:

• Growing seasonFrom spring to autumn, it is recommended to fertilize every 15-20 days with a balanced solid or liquid organic fertilizer. A nitrogen-rich fertilizer in spring and a higher phosphorus and potassium fertilizer in summer and autumn promotes balanced development and reduced leaf size in bonsai.
• Subscription reduction or suspension: During the winter and on extremely hot days, fertilization should be reduced or eliminated.
• Do not fertilize after transplants or drastic pruning.: You must wait for the tree to recover before resuming fertilization.
• Foliar fertilizer: It can be used occasionally to correct deficiencies, but excessive use can cause fungal problems.
• Dose control: Excessive fertilizer can cause excessive growth and weaken the overall vigor of the plant.

Chinese Elm Transplant: Frequency and Recommendations

Transplanting is essential to renew the substrate, eliminate damaged roots and promote root development.

• FrequencyYoung plants are transplanted every 1-2 years; adults, every 3-5 years. The ideal time is early spring, before budding, or after defoliation.
• Root pruningDuring transplanting, any dead or thick roots should be removed, maintaining the fine root system. If pruning is intensive, the foliage should be reduced proportionally.
• Substratum: It prefers mixes that retain moisture but drain very well. Akadama, volcanic gravel, and some peat or fine compost are good options.
• Use of hormones: It is not essential, but rooting hormones can be used with fungicide to increase the success rate, especially in radical transplants.
• Protect the tree after transplanting: It should be placed in a very bright location but avoiding direct sunlight for a couple of months, until it shows signs of active sprouting again.
• New and clean substrate: Never reuse soil from another crop, to avoid the transmission of pathogens and pests.

Pruning, pinching and shaping of Chinese elm (Ulmus parvifolia)

The Chinese elm is one of the most grateful species in terms of shaping and pruning.It tolerates both drastic pruning and frequent pinching, allowing it to be maintained in a variety of styles:

• Time to pruneThe best time is early spring, before bud break, or late summer after the summer dormancy has passed. It can also be done after successful defoliation.
• Pruning branches and shootsThe tree sprouts even from old wood. The recommended technique is to let the branches grow to 4 to 5 leaves and cut them back to 1 or 2 leaves to branch.
• Pinching: Essential for thickening the canopy and reducing leaf size. Always cut from a leaf whose bud points outward to guide growth appropriately.
• Defoliated: Allows for the renewal of internal shoots and a reduction in leaf size. This should only be done if the tree is very healthy and actively growing. After defoliating, it's a good idea to place the tree in full sun to encourage new shoots.
• Removal of unwanted shoots: Suckers from the base, crossed branches, very vertical or horizontal branches that grow inwards must be removed to enhance the silhouette of the bonsai.
• Intervals between operations: It is advisable to leave at least 3 weeks between drastic pruning and transplants, so as not to weaken the tree excessively.
• Recommended stylesInformal upright, broom, forest, and freestyle styles. Its flexibility allows it to adapt to most bonsai trends.

Wiring and forming techniques

Wire fencing is a valuable resource for shaping Chinese elm, although it should be used with caution:

• Time: It is carried out between autumn and spring, when the tree has lost its leaves or after defoliation.
• CooperationUse wire appropriate for the thickness of the branches. The marking must be carefully observed, as rapid growth can cause the wire to leave marks on the bark. Never use excessive wire to avoid damaging the tree or sacrificing its natural appearance.
• Wire removal: It is essential to remove the wire as soon as the branch has set the desired shape or if it is observed to begin to mark the bark.
• Alternative modeling: The use of trusses and strategic pruning is also effective in shaping Chinese elm.

Reproduction and multiplication of the Chinese elm

Reproduction of the Chinese elm can be done by several methods, with cuttings being the most popular and efficient, although you can also opt for seeds or air layering:

• Cuttings: They can be planted with tender or semi-woody shoots in early spring. Cut into 10 cm pieces, apply rooting hormone, and plant in moist, well-aerated soil.
• Aerial layering: An effective method for adult specimens. Practiced in early summer, lightly cut the bark off a selected branch, apply hormones, and wrap it in damp moss until roots develop. This method of seed stratification may be useful for some species..
• Seeds: It requires stratification and doesn't always yield successful results, as seed viability is often low. It's preferable to purchase fresh seeds and sow them in a special germination substrate.

The ease with which it forms roots and the speed with which it takes root make the Chinese elm one of the favorite species for propagation and thus expanding the bonsai collection.

Diseases and pests of the Chinese elm

The Chinese elm is generally hardy, but it is not exempt from certain phytosanitary problems. Among the most common are:

• Cochineal: A sucking insect that attaches itself to branches and leaves, weakening overall vigor. It can be controlled by manual cleaning and applying specific oils or insecticides.
• Aphid: It affects tender shoots, causes deformation, and is associated with the presence of ants due to the secretion of honeydew. It is controlled with mild insecticides and by improving ventilation and irrigation.
• Red spider: It occurs in warm, dry environments. It causes yellowing and leaf drop. Spraying leaves with water (but not excessively) and controlling ventilation helps prevent this.
• White fly: It settles on the underside of young leaves, progressively weakening the plant. Treatment is based on specific insecticides and improving environmental health.
• Mushrooms: Such as anthracnose, Dutch elm disease, rust, and leaf spot. Avoid excessive moisture and spray preventively in case of repeated outbreaks.
• ChlorosisYellowing due to iron or manganese deficiency, often caused by very calcareous water or alkaline soils. This is corrected by adding iron chelates.

General recommendations: Keeping the tree healthy, well-fertilized, well-ventilated, and in a suitable substrate minimizes the need for pesticides. If treatment is required, use products specifically for the identified pest and avoid systemic pesticides, which can be too aggressive and cause leaf drop.

Advanced care and tips for a spectacular Chinese elm tree

• Rotation: Turning the container periodically ensures uniform growth and a balanced canopy.
• Sheet size control: Full sun exposure, regular pinching, and a controlled nitrogen fertilization help reduce leaf size, which is essential in bonsai.
• VentilationEssential to prevent fungus and pests. If grown indoors, opening windows or using gentle fans is recommended.
• Disease preventionAvoid standing water in saucers under the pot and remove any dry leaves or branches promptly. General hygiene is key to your plant's health.
• Pot selectionUnglazed ceramic ones are ideal for allowing root transpiration; the size should be chosen based on root volume.

The Chinese elm and its use in bonsai

El Ulmus parvifolia It is one of the most popular and appreciated trees for making bonsaisIts features make it a versatile option for both beginners and experienced collectors:

• Responds well to modeling already intense pruning.
• Rapid development of fine branching and small, dense foliage.
• Highly adaptable to different styles, from informal vertical to forest or broom.
• Ease of maintenance and recovery against cultivation errors, making it ideal for those starting out in the art of bonsai.

Curiosities, history and traditional uses

The wood of elms, including the Chinese elm, has historically been valued for its hardness, water resistance, and impact resistance. It has been used in carpentry, boat building and furnitureThe bark, especially that of other species such as Ulmus minor, is used in herbal medicine as an astringent and soothing agent for minor ailments, although no herbal product should ever be used without medical supervision.

In Asian culture, the Chinese elm is rich in symbolism. In some traditions, it represents longevity and strength, and its roots, when rubbed dry, are said to produce sparks, fueling legends about its ancient power.

Tips for choosing your first Chinese elm

• Prefers specimens with a well-defined trunk, healthy bark and homogeneous branching.
• Look for small leaves and without deformities. Spots or yellowing may indicate deficiencies or disease.
• If you purchase it as a bonsai, check the substrate and roots to make sure they are healthy and not overly compacted.
• Always ask for information about the origin of the tree: those from specialized nurseries are usually better prepared to adapt to new conditions.

Frequently Asked Questions About Growing and Maintaining Chinese Elm

1. Can Chinese elm be kept indoors?
   Yes, as long as it has plenty of natural light and good ventilation.
2. Does it lose leaves every year?
   Not necessarily. In temperate climates, it acts as a semi-evergreen, retaining part of its foliage year-round.
3. How long does it take to branch?
   With regular pinching and good care, fine branching develops within a few months.
4. What to do if spots appear on the leaves?
   The first step is to check the irrigation system and water quality. If the problem persists, provide iron chelates or apply specific pesticides based on the diagnosis.

The cultivation of the Chinese elm (Ulmus parvifolia) offers an enriching experience for both beginners and experienced bonsai professionals. Its resilience, adaptability, and beauty make it a standout specimen both within and outside the art of bonsai, capable of surviving demanding conditions, responding well to shaping, and resisting pests and diseases that affect other species. With the care and attention detailed in this article, you'll enjoy a tree of great longevity and presence, capable of beautifying any environment with its appearance and changing colors throughout the year.