This attractive foliage plant from the tropics of N. and S. America, usually with beautiful variegated leaves, is an excellent plant for heated homes because they thrive in warmth, tolerate the dry air of forced air furnaces, and some reduced light. The large soft, fleshy leaves will reach 18ʺ (45 cm) in length and 6ʺ (15 cm) in width. They will have markings of white or cream in varying amounts depending upon the cultivar. A healthy plant will reach over 6’ (2 m) in height.
Light and Temperature
Can tolerate lower light but will have more color in the leaves with more light. Never place in direct sunlight. This plant really prefers warm temperatures above 75-80°F (24-27°C) and never below 60°F (15°C). They must not be in a draft. My plant is beside a north facing window and without artificial light I would not get all this variegation I like. You can see that the lower leaves are nearly all green. This plant did not get enough light when young. I am using a 10W LED bulb that provides 600 lumens which is about 55 footcandles. This is not much but in addition to the window light, for a foliage plant like this dieffenbachia, it is sufficient and doing well. Plants do need, long term, the full spectrum of color which LED is not providing but more on that later in the blog.
Keep the soil moist at all times. When the medium is dry to the touch it is time to give it water so it runs through but don’t let the pot sit in this water. Empty the saucer. Water less from late fall to early spring when the soil is dry about 1/3 down. Adding humidity is not necessary but can be helpful during the active growing season from early spring to late fall. Use a soft damp cloth to wipe dust from the leaves so the plant can ‘breathe’. An occasional gentle shower either indoors or out on a warm day will help with this and help keep any pests at bay.
A basic soil based media mixture of 1 part loam, 1 part light compost or leaf mold, 1 part sphagnum peat, and 1 part coarse sand will be a good mix for this plant. Because this plant likes to be kept moist be sure you have good drainage so the roots won’t rot.
Use a diluted balanced liquid fertilizer (liquid cow manure is suitable) every 2 weeks through the active growing period from early spring to late fall.
Flowers are rare to see on plants in the home but if you are lucky it will unfurl from the center like the leaves to form a spathe surrounding a spadix very similar looking to the Peace Lily flowers.
Pests and Problems
Leaves falling may be a sign of the plant being too cold.
Brown edges on the leaves may be a sign of soil too dry or waterlogged. You probably know if you water too much or have let it dry out.
Spider mites, thrips, and aphids may be attracted to this plant.
Each year or two, if your plant is growing rapidly, as these normally do, you can re-pot into the next size pot in the spring using a light, well-draining, medium as described above. When it gets to a size you like you can top-dress and prune rather than re-potting.
Can be propagated from tip cuttings of 4-6ʺ (10-15 cm) long using a rooting hormone before putting into a rooting medium. They must be kept above 70°F (20°C) in a plastic bag (bottom heat is helpful) or a propagator.
Lower leaves will drop as they age to form a thick bare stem leaving only the leaves at the top. You can propagate this now from stem cuttings placed horizontally on potting soil, in a plastic bag. This is a quite successful and easy method. You can even use rooting hormone and plant the top leafy section back to a more attractive level. It may root for you.
The common name of ‘dumb cane’ is due to the fact that the sap can cause a painful swelling on the mouth and tongue so wash your hands thoroughly after touching this plant. The irritant is not absorbed through skin but be careful if you have a wound on your hand. Do not let pets chew this plant or there may be numbness and swelling.
If you have done some remodeling in your home or if you just want to remove pollutants from your air the Dieffenbachia will help. It is efficient at cleaning formaldehyde from the air.
D. maculata ‘Tropic White’ – has large, blotched white leaves
D. maculata ‘Veerie’ – has green-yellow leaves with white blotches
D. picta ‘Rudolph Roehrs’ – has oblong pointed leaves 10-12ʺ (25-30 cm) long that are almost all yellow with ivory blotches and a dark green midrib and border. An excellent houseplant that will thrive in dry room conditions and low light but the more light it gets the more colorful the leaves will be.
D. bausei – has yellowing green with dark green and white variegation on a compact plant
D. bowmannii – has up to 30ʺ (75 cm) leaves flecked with pale green