Chinese elm (Ulmus parvifolia), or lace bark elm, is one of the most widely available types of bonsai trees and is easy to care for making it suitable for beginner bonsai owners. For maintenance, you'll want to keep the tree warm and the soil moist. Prune, shape, and move this bonsai tree as needed.
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Part 1 of 3: Environment
Step 1. Place the bonsai in a warm location
Ideally, the bonsai tree should be placed at a temperature between 15 to 20 °C.
- In the summer, you can put the bonsai outdoors. Once the temperature starts to drop to 15°C during the day and 10°C at night, bring the bonsai back into the house.
- In winter, keep the tree site temperature consistent between 10°C and 15°C. The temperature is low enough to cause the tree to enter dormancy, but high enough to prevent the tree from dying.
Step 2. Provide as much morning sun as possible
Place the bonsai in a location that receives direct morning sunlight and indirect daytime sunlight.
- In the morning, the sun's rays aren't too glaring, but during the day the effects can be too strong and the bonsai leaves can burn from it, especially in summer.
- If you decide to move your bonsai from indoors to outdoors, acclimatize it first to prevent the leaves from burning. Put it in the sun for longer periods of the day until your tree looks strong enough to spend the whole day outdoors.
- Sunlight also encourages Chinese elm foliage to stay small.
Step 3. Maintain good air circulation
Place Chinese elm in an indoor or outdoor location that gets plenty of airflow.
- When placing a bonsai indoors, place it in front of an open window or place a small fan nearby to increase the amount of air movement.
- While air circulation is great for bonsai, wind and gusts of frozen air can damage it. When you keep them outdoors, position them behind taller plants or structures that can help protect them from damaging gusts of air.
Part 2 of 3: Daily Care
Step 1. Allow the soil surface to dry out a bit
Insert your finger 1.25 cm deep into the ground. If the soil feels dry at that depth, add a little water.
- You may need to water your bonsai every day or two in the spring and summer, but the frequency of watering will decrease in late fall and winter.
- When you water a bonsai tree, take it to the sink and flush it with water from the faucet. Allow the water to seep through the holes in the pot a few times.
- In general, bonsai trees dry out quickly because of their rough soil and shallow growing containers.
- Specific watering schedules will vary depending on conditions, so it's a good idea to check the dryness of the soil instead of sticking to a single schedule.
- You can also try dehydrating the bonsai tree slowly, once or twice a week. Doing so will keep the soil moist. However, this should not replace regular watering.
Step 2. Fertilize the bonsai every week
In the growing season, provide special fertilizer for bonsai trees.
- The growing season covers from spring to fall.
- Wait for the bonsai to start producing new green growth before starting to fertilize it.
- Give a fertilizer containing nitrogen, phosphorus, and potassium in the same amount as written in the formula number (example: 10-10-10).
- If you use liquid fertilizer, apply it every two weeks. If you use pellet fertilizer, apply it once every month.
- Follow the instructions on the fertilizer package to determine the correct amount to use. Most fertilizers should only be applied when the plant is being watered.
- Reduce the frequency of fertilization once growth begins to slow in mid to late summer.
Step 3. Protect the bonsai tree from pests
Chinese elm bonsai trees can be attacked by the same pests that can damage houseplants. Apply a low concentration of organic pesticide as soon as you notice any signs of pests.
- Your bonsai tree may have started to be attacked if you notice abnormal leaf loss or branch management. Of course, another sign is the presence of insects on the bonsai.
- Mix 5 ml of liquid dish soap and 1 liter of warm water. Spray this mixture on the leaves of the bonsai tree, then rinse with clean water. Repeat this procedure every few days until the pest infestation is completely gone.
- Neem oil can be used instead of a soap solution if you prefer.
Step 4. Watch for signs of fungal disease
Chinese elm is susceptible to a fungal disease known as black spot. Treat this fungal attack, or any other disease that attacks it, with a fungicide as soon as possible.
- Black spots appear in the form of black dots on the leaves of the bonsai tree. Spray with a fungicide according to the directions on the label, then remove leaves that have more than half of the surface damaged. Do not apply condensation during the treatment period.
- Depending on the severity of the infection, you may have to give the treatment several times.
Step 5. Keep the area clean
Pick up dead leaves from the ground; bonsai abort it regularly and naturally.
- Also remove dust from leaves to encourage good air circulation.
- By keeping your tree clean, you can maintain its health and protect it from disease and pests.
Part 3 of 3: Long Term Care
Step 1. Arrange growth using wire
If you want your bonsai tree to grow into a specific shape, arrange it by wrapping wire around the branches and trunk.
- Wait until the new branch shoots appear to be starting to woody. Don't wrap the wire when the shoots are still green and fresh.
- You can shape the Chinese elm into most existing bonsai tree styles, but the recommended shape for it is the classic umbrella style, especially if this is your first bonsai.
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To form a bonsai:
- Wrap thick wire around the tree trunk. Wrap thin wire around branches and branches. At this stage, the tree branch should still be able to bend.
- Wrap the wire at a 45° angle. Don't wrap it too tightly.
- Bend the wire and the prongs it's wrapped around into the shape you want.
- Adjust the wire every six months. Once the branches are no longer able to bend, you can remove the wire.
Step 2. Prune new branch shoots to a node or two
Wait for new shoots to appear with three or four nodes, then prune them back to one or two nodes.
- Don't let the branches grow longer than four knots unless you're trying to thicken or strengthen them.
- The frequency of pruning bonsai will vary, depending on conditions. For best results, don't rely on an overly tight schedule; simply prune your tree once it starts to become irregular in shape.
- Pruning the new shoots will allow them to divide and produce a bushier bonsai.
Step 3. Remove the sucker root
The suckers are found on the underside of the stem and should be cut off at ground level as soon as they emerge.
- Sucker roots grow out of the roots and deplete nutrients from the main plant.
- If you want secondary stems in the sucker root area, you can let them grow instead of pulling them out.
Step 4. Prune intensively for a month before transplanting your tree into a new pot
With this treatment, the bonsai will have sufficient time to recover from the shock caused by pruning before experiencing a new shock from the removal.
Major pruning is usually done when the bonsai tree is at its strongest. That is, the right time to do it is in early spring or summer
Step 5. Transfer the bonsai to a new pot when the shoots start to swell
Younger trees will need to be moved once every year, while older trees will only need to be moved once every two or four years.
- Transfer the plant to a new pot in late winter or early spring. Place it in a slightly larger container with the same soil quality as the soil in the original container.
- Try sprinkling a layer of gravel on the bottom of the container before moving the tree into the new pot. The gravel will prevent the roots from being crushed by the soil, and will prevent root rot as well.
- You can trim the roots as you move the tree to a new pot, but don't trim too much. Chinese elm can go into shock if the roots are pruned too much.
- After placing the bonsai in its new pot, water the soil thoroughly. Place the bonsai in a location protected from direct sunlight for two to four weeks.
Step 6. Plant a new bonsai tree from the cuttings
You can grow a new Chinese elm bonsai tree from 15 cm pieces you get from the main tree in the summer.
- Make the cut using clean, sharp scissors.
- Put the fresh pieces in a glass of water. Roots will appear within a few days.
- Transfer the pieces to a new container containing 2/4 of the clay, 1/4 of the moss, and 1/4 of the sand. Water regularly until growth is stable.
