Botanical name: Dieffenbachia spp
Dumb Cane is a popular houseplant with large and highly decorative leaves. It is easy to grow and is a good air cleaner. It is native to the New World Tropics from Mexico and the West Indies south to Argentina. The stems are straight and may grow to a height of 5 ft under room conditions. The leaves are simple and alternate containing white spots and flecks which make it an attractive houseplant. The lower leaves fall to give the plant a False Palm effect. The common name, "Dumb Cane", is derived from the unpleasant effect of its poisonous sap on the mouth and throat. It is poisonous to both humans and pets if ingested. Always wash hands thoroughly after handling. According to a study carried out by NASA (National Aeronautics and Space Administration), Dumb cane was found to remove common VOCs like formaldehyde, toulene and xylene from indoor air.
There are many varieties of Dumb Cane available with varied leaf patterns and not all are easy to grow. The Dieffenbachia amoena and Dieffenbachia picta varieties are fairly tolerant and easy to grow. Dieffenbachia amoena has dark-green foliage with white bars, the stems can reach a height of 5 ft and the leaves are 1.5 ft long at maturity. Dieffenbachia picta is the most popular, bearing oval leaves with ivory white blotches or markings. Other varieties include Dieffenbachia oerstedii which bears all-green leaves with a prominent white mid-rib, the yellow-green Dieffenbachia bausei and the giant-leaved Dieffenbachia bowmannii among many others.
Dumb Cane prefers bright filtered light, away from direct sunshine. Direct sunlight will lead to leaf scorch while too bright light causes loss of leaf color. Turn the plant regularly to ensure it gets light on all sides, which prevents it from bending towards the light source. Learn more on how to ensure your plant receives the correct light in this guide on understanding light for houseplants.
Keep soil moist at all times for Dumb Cane but reduce watering in the cold months and maintain the soil fairly moist. Avoid waterlogging as it can lead to stem-rot. Learn more on how to water houseplants.
Average to above average warmth with a minimum of 150C is ideal for Dumb Cane. Protect the plants from cold draughts as they are very sensitive to cold temperatures which may lead to yellowing and wilting of the lower leaves. Find out more on temperature for houseplants.
Average room humidity is ideal for Dumb Cane. Brown leaf tips is an indication of low humidity. To raise humidity mist the leaves or set the pot on a wet pebble tray. Clean the leaves by damp-wiping with a soft cloth to get rid of dust.
Feed Dumb Cane every 2-3 weeks during the growing period with a balanced water-soluble nitrogen-rich fertilizer. Withhold feeding in the cold season as growth is minimal and feeding at this time can lead to fertilizer burn. Find out more on feeding houseplants.
Repot Dumb Cane annually at the beginning of the growing season. Use a pot 1-2 sizes larger and one that has drainage holes. The soil should be free-draining and rich in organic matter. Never allow the roots to sit in waterlogged soil as it may lead to stem-rot.
Pruning Dumb Cane involves removal of dead and yellow leaves to maintain the plant neat and tidy. With age, Dumb Cane becomes leggy and unattractive. Cut off the cane, leaving a 4 inch stump. Use the crown for propagation. The stump will resprout to produce a new plant. Learn more on how to prune houseplants.
Dumb Cane can be propagated at the beginning of the growing season from stem cuttings, from offshoots and from the top crown of leaves.
Propagating Dumb Cane from stem cuttings
Take 2-3 in. long stem cuttings of Dumb Cane, dip the lower cut-end in a rooting hormone and stick it in moist free draining rooting soil. Place the set up in a warm shaded place. Roots will develop in about 3-6 weeks. Once there is new growth, the plant can be transplanted.
Propagating Dumb Cane from offshoots
Some varieties of Dumb Cane produce daughter plants (pups or offshoots) at the base. Remove these pups with some roots when at least 10 in. tall and pot them in individual pots. Place in cool shaded place and maintain the soil moist through out until new growth emerges. Allow the plant to be well established before transplanting.
Propagating Dumb Cane from the top crown of leaves
Remove the top crown of leaves of Dumb Cane bearing about 3 in. of stem, apply a rooting hormone and stick it in moist free-draining rooting soil. Place the set up in a cool shaded place and maintain the soil moist until new growth emerges. Allow the plant to be well established before transplanting.
Too low temperature below 100C or cold draughts are the causes of this in Dumb Cane. Maintain average to above average temperature and protect Dumb Cane from cold draughts. Find out more on temperature for houseplants.
The cause of yellow lower leaves in Dumb Cane is underwatering. Ensure the soil is moist fairly moist at all times and never allow the soil ball to dry out completely. Learn more on how to water houseplants.
Dumb Cane is prone to Stem-rot Disease, which is encouraged by waterlogging and low temperatures. Cut out diseased parts and treat the plant a fungicide or discard if plant is badly damaged.
Exposing Dumb cane to direct sunlight or excessive brightness will lead to loss of leaf color. Move to a more shaded spot or protect it from direct sunlight. Learn more on how to ensure your plant receives the correct light in this guide on understanding light for houseplants.
Naturally, the lower leaves fall to give Dumb Cane a False Palm effect. If young leaves are falling the the causes are three. One is cold temperature; maintain average to above average temperatures. Two is dry air; raise the air humidity for Dumb Cane. Three is cold draughts; protect Dumb Cane from cold draughts.
Two reasons will cause leaves with brown edges in Dumb Cane. One is that the soil has been allowed to dry out; maintain the soil moist at all times and never allow the soil to dry out completely. Learn more on how to water houseplants. Reason number two is the air is too dry; raise the air humidity for Dumb Cane.
Too little light is the reason; move Dumb Cane to a brighter spot. Learn more on how to ensure your plant receives the correct light in this guide on understanding light for houseplants.
Dumb Cane (Dieffenbachia spp) is toxic to both humans and pets. If the leaves are chewed or ingested, they may cause temporary swelling of the tongue and the throat which may lead to a temporary loss of speech and hence the common name dumb cane. In severe cases suffocation may occur.