How to Grow Dieffenbachia (Dumb Cane)

The Dieffenbachia genus includes a large group of beautiful tropical perennials, but the ones most commonly grown in cultivation are D. sequine, D. oerstedii, D. maculata, and D. amoena. Several Dieffenbachia species have recently been reassigned with different names, so you may run into confusion on the precise naming of different varieties. Collectively, they are generally known as dieffenbachias or dumbcanes. The name "dumbcane" originated because chewing the plant can cause swelling of the tongue and difficulty speaking.

Dieffenbachias​ feature pointed, ovate leaves in a variety of combinations of green, cream, and white colors. A large, well-grown dieffenbachia can reach 10 feet, with leaves 20 inches long. However, the plants will rarely reach this size in typical indoor conditions, where 3 to 5 feet is more common. Dieffenbachia is a fast-growing plant that can achieve 2 feet in height within a year of planting a rooted cutting, provided it gets enough light.

Dieffenbachia Care

Dieffenbachia is a rather east plant to grow indoors, but the best results require the right lighting, fairly high humidity, and the right watering schedule.

Dieffenbachia is best grown as an indoor plant in bright, indirect sunlight. Plant it in fertile, well-drained potting soil with a high peat content. As a tropical plant, it will do best in high humidity. One way to provide this is to place the pot on a tray of pebbles that is kept wet. Misting the leaves can help during the dry winter months.

Like many indoor houseplants, overwatering is a common problem with this plant. Allow the top two inches of potting soil to dry out completely before watering thoroughly so that moisture drains through the bottom of the pot. If you wish, lower, weak leaves can be removed as the plant grows, creating a specimen resembling a small palm with an arching canopy.

Dieffenbachia plants are largely trouble-free, but like many indoor plants, they can be susceptible to spider mites. Treat these with a horticultural oil rather than pesticides.

Light

Dieffenbachia plants are popular indoor plants largely because they do well in shady conditions, but these plants do appreciate bright light during the winter months. During the growing season, the plant prefers dappled shade or indirect light. The plant will favor the side facing the light, so periodically rotate the plant to keep its growth balanced.

Soil

Use a fast-draining, well-aerated potting mix. Make sure drainage is good to avoid damaging the roots; they should never be left in soggy soil.

Water

During the growing season, dieffenbachias like regular moisture and do not want to dry out. A large dieffenbachia might need to be watered twice a week, but in the winter, cut back on the water. At the same time, it's important not to overwater a dieffenbachia, which can cause rot problems. Make sure the top of the soil is fully dried out before watering.

Temperature and Humidity

This plant likes fairly warm conditions, from 65 to 75 degrees Fahrenheit. If the temperature drops below 60 degrees Fahrenheit or if the plant is exposed to cold drafts, it is likely to lose lower leaves and assume a palm-like appearance.

Fertilizer

For best results, feed regularly (every 4 to 6 weeks) with a balanced, diluted fertilizer, such as a 20-20-20. However, some growers swear by a routine of using a weak diluted fertilizer at every watering.

Is Dieffenbachia Toxic?

Dieffenbachia leaves contain needle-like calcium oxalate crystals called raphides, which can cause severe burning and swelling of animal tissues, both external and internal. This plant is considered moderately toxic, warranting medical attention if symptoms are severe. Remember to wear gloves when exposure to the sap is possible. This plant is best for experienced gardeners who have the skills to keep it alive and help it flourish

Symptoms of Poisoning

The raphides found in dieffenbachia leaves can cause burning and swelling of the skin, tongue, mouth, and throat. In rare instances, this swelling can be so severe that it renders a person unable to talk, and it can even block breathing. Death is rare in humans because of the instant unpleasantness experienced when the leaves are chewed, but there are cases of children under the age of five dying from ingesting dieffenbachia leaves. Fatalities are more common in pets that chew on the leaves.

Recommended treatment is to rinse the mouth and skin, and to call a doctor if any swelling of the mouth and throat is experienced.

Dieffenbachia Varieties

Of the many species of Dieffenbachia, only a few are commonly sold commercially:

• D. seguine is the most popular Dieffenbachia species, a native of Brazil with clusters of large ovate leaves with green margins splotched with yellow or cream color. It can grow as tall as 10 feet.
• D. maculata (formerly known as D. picta). Good cultivars include 'Perfection', with intensely variegated 8-inch leaves; 'Rudolph Roehrs', with fully yellow leaves with ivory splotches; and 'Superba', with thicker leaves and white variegation. 'Camille' has pale yellow leaves with white margins and grows to about 3 feet.
• D. amoena is a large, 6-foot plant with 20-inch leaves. One notable cultivar is 'Tropic Snow', which has smaller leaves and more variegation.

Be aware that various species of Dieffenbachia have undergone reassignment, and species names may change.

Propagating Dieffenbachia

There are three very easy way to propagate a dieffenbachia plant:

• During repotting in the spring, offsets can be divided (leaving some roots intact) and planted in their own pots. If you take this route, make sure not to damage the root systems of the parent plant in the process, and use a sterilized tool to avoid spreading disease.
• In older, leggy dieffenbachias, the top can be cut off and potted into fresh potting soil with a rooting hormone. New leaves will sprout from the stump. Once new leaves appear, remove the older leaves.
• Pieces of the cane can be sprouted by laying them horizontally in damp potting soil. As the pieces take root, leaves will gradually sprout.

Potting and Repotting Dieffenbachia

Repot annually for best results—simply lift the plant as a whole, knock away any old soil and dead material from the roots, and replace it in a larger container. Watch out for signs of stress on the plant, such as roots poking out from the surface, crowding, or falling leaves, which could signal that the plant needs repotting. After repotting a dieffenbachia, give it some time to adjust to its new setting. Make sure to wear gloves to avoid contact with the sap.