Prized for their glossy foliage and tiered growth habit, umbrella trees (Schefflera actinophylla) add a lush, tropical look to home interiors and outdoor landscaping within U.S. Department of Agriculture plant hardiness zones 9 to 11. Both indoor and outdoor umbrella trees require little routine care once established in a suitably bright, humid location. However, indoor specimens may need extra attention to ensure their longterm health and survival.
How to Care for an Umbrella Tree Indoors
Water umbrella trees deeply but infrequently. Pour water onto the soil until it is saturated and roughly 10 percent of the water has trickled from the drainage holes. Let the soil dry out in the top 2 inches before watering again. Reduce water by half during the winter to prevent root rot.
Maintain temperatures above 75 degrees Fahrenheit during the day and 65 degrees Fahrenheit at night. Shield the umbrella tree from heating and cooling vents to prevent thermal stress. Mist the foliage daily or place the pot on a tray of moist pebbles to raise the humidity level around the plant.
Feed umbrella trees using liquid fertilizer with an N-P-K number of 20-20-20. Dilute 1 teaspoon of fertilizer in 1 quart of water. Replace one watering per month with the fertilizer solution. Reduce feeding by half during the winter or if the umbrella tree is growing under low light conditions.
Prune umbrella trees only to control their size or remove dead stems. Remove no more than one-third the total length of the stem when pruning, and make the cut straight across rather than angled. Sanitize the pruning shears before use by soaking them in a 50-50 solution of rubbing alcohol and water for five minutes.
Repot umbrella trees if they outgrow their pot, which occurs every two to three years in established plants. Move them into a pot with multiple drainage holes in spring, and use standard potting soil containing peat and perlite to provide the correct drainage and moisture retentive properties.
Watch for signs of common pests such spider mites, mealybugs and scale. Treat pest problems with a non-toxic insecticidal soap solution. Combine 2 teaspoons of dish soap and 1 pint of water in a spray bottle. Spritz the solution onto the leaves and stems, paying special attention to the undersides of the leaves. Reapply the solution weekly until the problem subsides.
Watch for signs of salt buildup in the soil such as a whitish crust on the surface and a generally unwell appearance in the plant. Scoop out the salty white layer of soil and replace it with fresh soil. To prevent salt buildup, leach the soil every few months by running fresh water through the pot.
How to Care for Umbrella Trees Outdoors
Water outdoor umbrella trees weekly during the summer to keep their roots healthy and hydrated. Run water at the base of the tree until the soil feels very moist in the top 4 inches. Let the soil dry out completely on the surface between waterings. Withhold water during the winter, except if no rain has fallen for longer than a week.
Mulch outdoor umbrella trees to conserve water and help keep their soil moist. Spread a 3-inch-thick layer of lightweight organic mulch beneath the umbrella tree, from the base of the trunk to the edges of the drip-line. Replace the mulch each year in spring.
Prune outdoor umbrella trees only to control their size or to create branches with different heights. Snip off no more than one-third the height from the main branch, making a cut just above a set of foliage. Sanitize the pruning tools before use by soaking them in a 50-50 solution of rubbing alcohol and water for five minutes.
Protect outdoor umbrella trees from cold temperatures in USDA plant hardiness zone 9. Cover the tree with breathable fabric such as burlap if temperatures are expected to drop below 40 degrees Fahrenheit, and keep the soil surrounding it moist so it will retain more warmth. Remove the covering once the cold temperatures pass.
Feed outdoor umbrella trees only if signs of nutrient deficiencies occur, such as yellow foliage combined with unusual leaf loss. Apply general purpose, 20-20-20 ratio fertilizer to moist soil beneath the tree's drip-line at a rate of 1 pound per 100 square-feet of area. Feed only during the active growing season, from spring until midsummer. Do not feed after midsummer because the new growth will not have time to harden before cool weather sets it.