Prepared by Karen Russ, HGIC Horticulture Specialist, and Al Pertuit, Extension Floriculture Specialist, Clemson University. (New 03/99.)
Dieffenbachias are easy houseplants that tolerate a wide range of conditions. They are popular in homes and offices for their colorful, large leaves.
The common name dumbcane results from a mouth numbing substance in the stem and leaves. Some people may get a skin rash from the plant's sap. This plant can be toxic if eaten.
Most dieffenbachias will grow from 3 to 6 feet tall and 1 to 3 feet wide. Individual leaves can be 18 inches long by 12 inches wide.
Dieffenbachias will grow quickly in ideal conditions or barely at all if light is low.
Dieffenbachia is grown for its eye-catching leaves. Large, tropical-looking leaves in many shades of green are marked with spots, stripes, dots or colored veins.
In the home, plant diseases are very rarely a problem. Too much or too little water plus insects and mites are the main problems. Root rot usually results from a soil mix that does not drain quickly or overly frequent watering.
Mealybugs and aphids suck plant juices and heavy infestations will coat the leaves of dieffenbachia with sticky honeydew.
Too much fertilizer can cause marginal leaf burn. If plants are lacking nutrients, they may yellow, produce smaller leaves and become stunted.
Dumbcanes thrive when given bright filtered light in spring, summer and fall. Bright light, even direct sunlight, is best during winter. They will tolerate low light, but growth will be reduced.
Water thoroughly, then let soil dry to the touch to a depth of one inch. Dieffenbachias will grow well in most well-drained container soil mixes. They should be fed from March through September with a foliage houseplant fertilizer. Liquid-type fertilizers can be applied at half strength every two to four weeks, or you can use a time release fertilizer applied according to label directions.
Dieffenbachias enjoy normal warm household temperatures. Temperatures from 60 to 75 °F are ideal. Always protect dieffenbachias from cold and major changes in temperature.
As these plants mature, lower leaves naturally drop to reveal attractive, trunklike stems. If the stems become too long and bare, you can rejuvenate the plant simply by cutting the stems back to about 6 inches tall. The plant will regrow below the cut.
If repotting is necessary, do so in early spring. Propagation is by cane cuttings, stem tip cuttings or air layering done in spring or early summer.
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