During the summer, you can usually keep the bonsai outdoors. You’ll need to bring it indoors once temperatures start dropping below 15 degrees Celsius (60 degrees Fahrenheit) during the day and 10 degrees Celsius (50 degrees Fahrenheit) during the night. [2] X Research source During the winter months, it might actually help the tree if it is consistently kept between temperatures of 10 and 15 degrees Celsius (50 and 60 degrees Fahrenheit). These temperatures are low enough to send the tree into dormancy but high enough to prevent the tree from dying.
Morning sunlight isn’t too intense, but direct sunlight in the afternoon can be too strong and may burn the leaves of the bonsai, especially during the summer months. If you decide to move an indoor bonsai outdoors, let it acclimate to direct sunlight slowly to prevent the leaves from burning. Keep it in the sun for longer periods of time day after day until it seems strong enough to spend an entire day in the sun. Sunlight also encourages the leaves of the Chinese elm to stay smaller.
When keeping the bonsai inside, 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 good for the bonsai, you should also note that cold drafts and winds can cause damage. When you keep it outside, position it behind a taller plant or structure to help protect it against nasty gusts.
You will probably need to water the bonsai every day or two during the spring and summer, but this frequency will probably decrease during the late autumn and winter months. When you water the bonsai, take it to the sink and let it shower it with water from above. Let the water drain out through the bottom drainage holes several times. Bonsai, in general, have a habit of drying out quickly due to the coarse soil and shallow container they grow in. Note that specific watering schedules will vary on a case-by-case basis, so you should test the soil for dryness rather than relying on a single schedule. You should also consider misting the tree gently once or twice a week. Doing so will keep the soil moist. This routine should not replace regular waterings, though.
Note that the growing season is spring through fall. Wait until after the bonsai begins to produce new light green growth before you start feeding it with fertilizer. Apply a fertilizer that contains equal parts nitrogen, phosphorus, and potassium, as indicated by its formula number (example: 10-10-10). If using liquid fertilizer, apply it every two weeks. If using pellet fertilizer, apply it every month. Follow the instructions on the fertilizer package to determine the proper amount to use. Most fertilizers should be applied when the plant is being watered. Reduce the frequency of feedings once the growth slows down in the mid-to-late summer.
Your bonsai might have a problem if you notice abnormal leaf dropping or stickiness on the foliage. Visible insects are, of course, another telling sign. Mix a solution of 1 tsp (5 ml) liquid dish soap and 1 quart (1 L) tepid water. Spray this mixture on the leaves of the bonsai, then rinse it off with clean water. Repeat this procedure every few days until the problem goes away. Neem oil spray can be used instead of a soap solution, if desired.
Block spot appears as dark spots on the leaves of the bonsai tree. Spray with a fungicide according to label instructions, then remove any leaves that are more than half damaged. Do not mist the tree during this time. Depending on the severity of the infection, you may need to treat the bonsai multiple times.
You should also keep dust off the leaves to promote good air circulation. Keeping the tree clean is a good way to keep it healthy and protect it against both disease and pests.
Wait until new shoots become slightly woody. Do not wire them when they are still fresh and green. You can wire the Chinese elm into most bonsai styles, but the classical umbrella shape is recommended, especially if this is your first bonsai. To train a bonsai: Wrap heavy gauge wire around the trunk of the tree. Wrap thin, light wire around the stems or branches. The branches should still be pliable during this time. Wind the wire around at a 45 degree angle and do not wrap it too tightly. Bend the wire and its corresponding branches into the shape you desire. Readjust the wire every six months. Once the branches are no longer pliable, the wire can be removed.
Do not let the branches grow too much longer than four nodes unless you are trying to thicken or strengthen it. The frequency with which you need to prune the bonsai will vary on a case by case basis. For best results, do not rely on a strict schedule and simply prune the tree once it starts looking out of shape. Pruning new shoots will allow them to divide, ultimately creating a fuller, bushier bonsai rather than a thin, lanky one.
Suckers grow out from the root and deprive the main plant of nutrients. If you want to grow a secondary branch or trunk in the area of the sucker, however, you can let it grow instead of removing it.
Note that major pruning is also usually done when the bonsai tree is at its strongest. This means early spring or early summer.
Repot the plant during the late winter or early spring. Place it into a slightly larger planter with the same quality soil used in its current container. Consider spreading a layer of pebbles in the bottom of the container before repotting the tree. These pebbles can prevent the roots from sitting in soil, thereby preventing root rot, as well. You can prune the roots as you repot the tree, but avoid any heavy root pruning. The Chinese elm may go into shock if the roots are pruned back too far. After placing the bonsai in its new pot, water the soil thoroughly. Keep the bonsai in a shady spot for two to four weeks.
Take the cuttings using sharp, clean scissors. Place a fresh cutting in a glass of water. Roots should develop within a few days. Repot this cutting in a planter containing two parts loam, one part peat moss, and one part sand. Water regularly until the plant establishes itself.
