Hawaiian Umbrella Tree Care Guide
Schefflera arboricola – also known as Dwarf Schefflera – is a native of Taiwan and grows in tropical and subtropical regions as a shrub or small tree. In the ground, the tree may grow to 10-25 feet tall. This plant is often used for bonsai because of its unique look and ease of care, as well as its ability to be grown indoors.
The compound leaves on this dwarf cultivar are dark green and glossy and form a little umbrella shape, almost like a tiny palm tree. The trunk is slender, light tannish to gray, and develops an interesting aged wood look over time, especially if aerial roots form.
The Hawaiian Umbrella loves balmy temperatures and should not be exposed to air under 59 degrees Fahrenheit. The ideal range for this plant is 64-71 degrees. It will enjoy some time outside in the summer but be sure to bring it back inside once the cool fall weather sets in. When indoors S. arboricola should be given plenty of time in a sunny window. The more light it receives, the smaller the leaves will be and the better the trunk development. Too little light could cause it to become leggy, which is not conducive to bonsai formation.
Water this species often enough to prevent it from completely drying out, but don't allow the roots to soak. Run water into the pot until it starts draining out the bottom, in order to prevent salt buildup. If you want aerial roots to form use a humidity tray, as the higher the humidity level the better chance that the plant will produce these fascinating roots.
Feed this bonsai a regular houseplant fertilizer at half-strength, once a week. Water the tree thoroughly prior to feeding. Decrease feeding frequency to monthly during the winter. Some experts advocate a low nitrogen bonsai mixture as excess nitrogen may stimulate leaves to grow larger.
Styles – the Hawaiian Umbrella is best suited for upright styles that utilize a large canopy of foliage. Because the woody parts of the tree aren't actually true wood (there is no wood core and growth rings do not develop) it may not take well to wiring or drastic repositioning of branches. Because of the banyan appearance of the roots, and particularly if aerial roots are present, Schefflera makes for amazing group arrangements or multiple trunk styles. Root over rock is also easy with this specimen and the results can be visually stunning.
For shaping, trim the tips of shoots once they reach the desired length. Larger leaves may be removed but the leaf stalks will fall off on their own. If an attempt at wiring is to be done it should be carried out when the shoots are still young, being cautious not to damage the bark. Wrap the wire loosely and make gradual bends over the course of a week rather than all at once.
May be carried out either by seed propagation or cuttings. After retrieving the seeds, immediately place them in bonsai soil or a balanced blend of peat moss, loam, and sand. Cover the seeds with soil or sand. Cuttings can be set in a granular soil mix which is dampened and then sealed in a plastic bag, container and all. Wait about four to six weeks for the cuttings to set roots, then remove from the bag and plant. Too much water can result in a failure to grow roots.
Hawaiian Umbrella may be repotted in the spring every other year, as soon as night temperatures remain in the high 60s. It can be repotted at any time afterward, including throughout the summer. The roots are rather delicate but can withstand a good, healthy pruning. This bonsai does well with a mixture of half inorganic matter and half bark. Repotting is also a good time to remove all of the leaves that are too large.
Insects/Pests & Diseases:
Schefflera arboricola can be susceptible to a number of pests and health problems. Yellow, sticky, or discolored leaves can indicate a pest infestation. This plant sometimes falls under the attack of aphids, scale, or mealy bugs. Scale must be removed by hand or by applying rubbing alcohol to their shells. Most other insects, including aphids, can be washed off using a mixture of a teaspoon of dish soap in a quart of warm water. Spray on until run-off occurs then rinse with a spray of plain water.
Fungicide may be used if signs of fungus are seen. Be sure the plant has well-draining soil to avoid root rot, and examine it routinely for any signs of a problem – black spots, discolored or mottled foliage, leaf drop, or any other sign of stress. Keeping your bonsai well-fed, well-watered, and well-drained will go a long way toward prevention of any potential damage from pests or disease.