The showy, speckled leaves of Dieffenbachia or Dumbcane have made it one of America’s favorite houseplants for decades.
Dieffenbachias are easy care houseplants, requiring only moderate light and water. If you have small children or nibbly pets you should take note that the common name “dumbcane” comes from the fact that it can cause very painful swelling of the mouth and throat if eaten, resulting in an inability to speak. While painful, there are very few records of people actually dying from eating Dieffenbachia (as it reportedly tastes awful). The sap can also cause irritation of the skin so be cautious if pruning these plants. Casual contact with unbroken leaves is harmless.
Moderate to low light, though in low light the plant will eventually become lanky and the attractive patterns on the leaves will become dull. Avoid direct sun as it can cause leaf scorch or bleaching. Like many houseplants, Dieffenbachia do well when summered outdoors in bright shade.
Regular home temperatures are fine. Dieffenbachias do not like to be chilled so be careful they are not exposed to cold drafts in winter. Like all tropical plants that prefer higher humidity, be careful not to place them too near a radiator or air vent as this can dry the leaves too much.
Water thoroughly when dry, then allow to dry fully before watering again. Fertilize monthly in summer with any balanced houseplant fertilizer mixed at half strength, or apply Osmocote in late spring.
Greenish-white flowers may develop but are not particularly showy. Feel free to snip them off (avoiding contacting any sap, of course).
Repot any time if necessary, but preferably in early summer as new growth begins. If you want to keep the plant close to its current size for a s long as possible, just replace the soil with fresh rather than increasing pot size- Dieffenbachias will grow larger in a larger pot. Any good-quality potting soil can be used.
Refreshing a lanky plant
If your Dieffenbachia is lanky with lots of bare stem, the plant can be refreshed by lopping the tops off-even to the point of removing all the leaves. (Again, watch out for the sap.) Do this in late spring and make sure the Dieffenbachia is in a bright area to encourage growth. In a few weeks, new buds will form at the bamboo-like “joints” of the stem. These will eventually develop into new leaves and your Dieffenbachia will regain its bushy form.
Dieffenbachias may develop spider mites in very dry environments. Mealybugs seem to be attracted to Dieffenbachias and can become a problem. Be sure to check your plants regularly, particularly in winter. Catching a pest problem early can mean the difference between easy treatment and throwing the plant on the compost pile.
Leaf edges turn brown-This is usually a watering issue…unfortunately both too much and too little water can produce the same symptoms. Recall your watering habits to determine which the likely culprit is. Remember to water once the soil is dry, but don’t allow to wilt, and never leave the plant sitting in a saucer of water.
Lower leaves yellow-Lower leaves will naturally yellow and drop as the plant ages. If many yellow at the same time the environment may be at fault, or your watering is off-this can happen after the plant gets dry enough to wilt badly.