Chinese Elm
(Ulmus parvifolia)
Country of Origin : Originated from China, Korea and Japan. Now found in many temperate environments.
Bonsai Styles : Informal upright, semi-cascade, cascade, twin trunk, broom
Zone : 5 – 9
A deciduous tree, Chinese elm bonsai tree is perfect for those new to bonsai. (However, these trees can be evergreen when grown indoors in warm climate).
Ulmus parvifolia bonsai can be grown in both indoor and outdoor settings. The tree thrives in the sun and the cold, producing new shoots from all parts of the tree.
The leaves are with serrated edges and dark green in color. They turn yellow to a reddish color in late fall. The tree produces small red flowers and green fruits.
Leaves on Chinese elms grow alternately at regular, short intervals on the shoots, and a new shoot appears almost every time a leaf is pinched.
This leaf growth pattern on shoots creates a herringbone pattern. This predictable pattern makes it very easy to prune the bonsai tree in shape and maintain the bonsai style, even for an inexperienced bonsai grower.
There are many varieties of Chinese elm that can be used to make bonsai. Some varieties have thick corky bark and some varieties display smooth bark.
The smooth bark varieties tend to be less hardy and need to be acclimatized slowly to the cold weather.
Typically, rough bark Chinese elm bonsai trees are grown outdoors and smooth bark varieties are grown indoors.
There are numerous cultivars of Chinese Elm, notably ‘Hokkaido‘ (characterized by its small leaves and corky bark), ‘Uzen‘, ‘Catlin‘ and ‘Nire‘, which are all grown for bonsai in Japan.
Best location to keep Chinese Elm Bonsai
In early and late summer, you can keep the tree in full sun. However, during the hottest parts of summer, you can keep the Ulmus parvifolia bonsai in partial shade.
Keeping Chinese elms indoors, near a sunny window, requires dappled shade, but they can also thrive in shadier conditions. Do not expose the plant to direct sunlight through glass of the window.
In shade the growth of the plant will be relatively slow but it will improve the leaf health and also improve the fall color of the leaf.
As mentioned earlier, if kept outside, these trees will be deciduous and in indoor settings these trees are evergreen.
Temperatures between 70°F to 85°F (21°C to 29°C)are ideal for growing from spring through summer. During winter, a temperature range of 60°F to 65°F (15°C to 18°C)is good for the plant.
Root damage and die-back of fine shoots can occur at temperatures below 23 °F (-5°C).
Protect the bonsai tree from wind and prolonged rain.
Refer sunlight requirements for indoor plants for more indoor gardening ideas. Also, refer to do bonsai trees need sunlight for more indoor and outdoor bonsai location ideas.
Propagation of Chinese Elm
Chinese Elm tree can be propagated by using softwood or hardwood cuttings in early summer. Specially for dwarf cultivators.
They can also be propagated by using root cuttings in winter.
Watering Chinese Elm Bonsai
Keep them well hydrated from spring to autumn, and increase the amount of water in summer. More often if necessary during extremely hot weather.
Make sure the compost is always moist, rather than letting it dry out before watering.
During the winter, keep the compost just moist.
Keeping Chinese elm soil slightly moist is best, but over-watering can cause root issues, so make sure you’re careful.
Read watering bonsai tree for more details about immersion technique.
Wiring Chinese Elm Bonsai
In the spring and summer, when branches are growing actively, it is ideal to wire them when they are younger and more flexible.
A branch grows quickly and hardens into shape.
Branches that are heavy should be wired from time to time so as not to curl upward.
Also, secondary and tertiary branches should be wired so that a good branch structure can be developed.
You can leave the wires on the tree for one growing season.
Pruning Chinese Elm Bonsai
When to prune Chinese Elm bonsai?
How to prune Chinese Elm bonsai?
You can prune indoor Ulmus parvifolia bonsai at any time of the year. Outdoor Ulmus parvifolia bonsai can be pruned in mid-spring just before the buds burst.
You should remove large branches in midsummer, when calluses are more likely to form quickly.
During the early stages of growth, let branches grow freely and thicken to gain strength, and then cut them back hard to two or three leaves. Repeat this process to develop tapered branches.
Branches that are not needed can be pruned in spring.
Mid-summer pruning will result in masses of new growth around the wound. By hard pruning in midsummer, weak branches can be strengthened, and new shoots will be allowed to grow.
Almost all elms respond well to leaf-cutting during the summer, however it is not usually necessary for smaller leafed forms such as Ulmus parvifolia.
As the tree produces alternate leaves on the shoots, the ‘clip-and-grow’ method of pruning is especially effective in Chinese elms because it simplifies the process. Prune the branch just above a leaf pointing in the direction in which you would like it to grow the branch.
Prune the tree three weeks before repotting the plant.
Pinching Chinese Elm Bonsai
Leave one or two leaves on each new shoot after pinching out the top. Continue through out the growing season.
Congested foliage and dead shoots should be thinned as often as necessary, probably twice a year.
Repotting Chinese Elm Bonsai
When to repot Chinese Elm bonsai?
Chinese Elm bonsai tree can be repotted every 2-3 years in early spring.
However, when the tree is 10 years old, then you can repot the bonsai depending on the root development (in case when the roots are container bound).
If blunt tools are used, the roots are easily damaged because the bark on the roots is slick and fibrous.
The roots of plants grow rapidly, so aggressive root pruning is advisable. Pruning hair roots by a third is a good idea.
You can use a free-draining, bonsai soil mix or Akadama.
OR
You can also use a soil mix consisting of 40% grit and 60% organic matter.
OR
You can also make a soil mix of loam, sharp sand and peat (or compost) in the ration of 1:1:1.
Must Read: Bonsai Soil Recipes
Must read : Choosing the right bonsai container
Feeding Chinese Elm Bonsai
When the tree is actively growing, feed it a balanced feed once a week.
Use a weak low-nitrogen fertilizer if growth continues in winter (temperature above 60°F (15°C) mostly in an indoor environment).
Apply nitrogen-free feed in the fall if the container is kept outdoors.
Read more about bonsai fertilizer and its application.
Diseases and pest of Chinese Elm Bonsai
Leaf gall and insects like aphids and scale insects, and sometimes spider mites can affect Chinese elm bonsai trees. Use an insecticidal spray.
A plant placed in a location with poor air circulation or with dry roots will be effected by mildew.
Bonsai elm trees are not susceptible to Dutch elm disease (fatal insect-borne disease that affects garden trees).
Do not use systemic insecticides or fungicides. They will cause Chinese elm trees to lose their leaves. This can even case slowing of growth rate or even die-back of the plant
Chinese Elm bonsai care
In case you are growing Chinese elm in a small bonsai pot, take special care as these pots dry out more quickly.
Changes in location or local environment may cause Chinese elms to lose foliage, but they will soon recover.
This plant has fleshy roots that are filled with water. Dryness or heavy rain can cause imbalance between the bonsai soil and the roots. If the pot is frozen at this time, the roots will explode or implode because of water freezing and expanding.
Providing that temperatures seldom reach freezing, they can be left outside all winter long. However this will cause some foliage loss. As a matter of fact, Chinese elms shed their foliage in response to stress of any kind.
What to look for when buying Chinese Elm Bonsai
Ulmus parvifolia is among the few bonsai species which can achieve a look which resembles a natural tree.
When making a purchase, look for a bonsai specimen which has decent branch structure, a tree like trunk structure, and a natural looking root spread.
Do not worry about the stray shoots and branches as these can always be pruned and reshaped. Only make sure that the foundational structure is tree like.
