Dieffenbachias or Dumb cane, are hands down, one of my favourite plants. This popular leafy house plant has 20 different varieties and so far, I have three of them, and hope to slowly but surely build up my collection until I have them all. They are beautiful leafy plants that come in a wide range of leaf patterns. But a common complaint about dieffenbachia’s is that their leaves turn yellow. 

The first sign of a dieffenbachia being unwell is that its leaves turn yellow and fall off. Usually it is easy to figure out what is wrong with the care and change it before the plant dies. Here are some tips to keeping your Dieffenbachias healthy and happy.

Watering Matters

The leaves of a dieffenbachia will turn yellow and the plant will get distressed if it is over or under-watered, so if the soil is very wet, let it dry out slightly until it is dry at the top. Too much water can drown the roots, so before watering, make sure that the soil is dry to the first knuckle. If it is any drier, the leaves will turn yellow and then brown and the plant will ultimately die from underwatering. 

Sometimes if the plant is in a pot that is too large for the root system, it will suffer. The plant should have no more than two inches around and beneath the root system, otherwise, the soil will not dry enough in between watering. This causes the roots to stay wet for too long and get root rot. 

If you overwater, let the root system dry out by waiting seven to 10 days in between watering. Make sure the plant is repotted into a proper pot if the pot is too large for the roots and remove all of the yellowing or dying leaves from the plant. This should bring the plant back to a healthy state. 

It is also beneficial to make sure your dieffenbachia is planted in well-draining soil with perlite. The better the roots drain the more chance there is that the plant will remain healthy.

Avoid Bright Sunlight

Dieffenbachias thrive in partially shady conditions but can experience stress in bright areas. Sometimes if a dieffenbachia is in sunlight that is bright or direct, it will droop and ultimately die. Bright sunlight can scorch the leaves and cause death.

If you suspect that sunlight is the culprit to your dieffenbachia being unwell and turning yellow, put it back from the window so that all the light it receives is indirect. It needs some sunlight but never directly onto its leaves.

Low Temperatures Are A No-No

Dieffenbachias should be kept in 65 to 75 degrees Fahrenheit (18-24 degrees Celsius) conditions. If the temperature gets too much lower than that on a consistent basis, your plant will droop and eventually die. 

If the leaves don’t turn yellow before they droop, it is a sign that the plant is too cold.  Don’t allow the room your dieffenbachia is in to get cooler than 55 degrees (13 degrees Celsius). A drafty area can also affect a dieffenbachia. The temperatures need to be warm and consistent. 

Nutrient Deficiencies 

If a dieffenbachia doesn’t get the proper nutrients, it can cause yellowing of the leaves. In extreme cases, if the plant is nutrient deficient for too long, it can die. The cause for this can be that the soil it is in is not nutrient-rich enough for a dieffenbachia. Dieffenbachias thrive in pure peat moss or a 1:1 peat moss and perlite mix. 

They can also do well in a 1:1:1 peat moss, perlite, and soil mix but avoid planting a dieffenbachia in pure soil with no peat moss. Be sure to give your dieffenbachia a complete fertiliser such as 20-20-20 every 4 to 6 weeks during its growing season.

The Root System

Dieffenbachias are prone to being root-bound. They have an extensive root system and when they get too tightly wound, the plant suffers. You can tell if the plant is getting too root-bound by looking at the watering holes in the pot. If the roots are coming out of the holes, then the plant is root-bound. 

Transfer it to a larger pot but not more than 1 to 2 inches bigger than the root ball as that can cause problems for the health of the plant as well.

Infestations

The most common infestations for dieffenbachias are mites or aphids. Check under the yellow leaves for web-like material for a spider mite infestation, and examine the leaves for aphids. 

To solve a pest problem, use insecticidal soap on the leaves or wipe the leaves down with a cotton ball saturated in Neem oil.

While there are several reasons why your dieffenbachia is not thriving or its leaves are turning yellow. Usually, the problem is easy to fix, but once the leaves have started to turn it is only a matter of time before the whole plant turns yellow and dies. 

Try to gently pull or snip off the yellow leaves with a pair of clean and disinfected shears so they don’t infect the others. Often, yellow leaves is the result of the watering schedule or temperature, so those are the two things I would try and fix first. But in general, dieffenbachias can live a very long and happy life as long as you understand its needs.