The Dieffenbachia or Dumb Cane plant is a common houseplant you’ll see in many homes. If you notice the plant’s leaves turn yellow, it is sign that it isn’t getting the care that it desires.
Why are your Dieffenbachia leaves turning yellow? Dieffenbachia leaves turn yellow for a number of reasons. The most common is overwatering.
However, lighting issues, low humidity, extreme temperatures and pests can also cause its foliage to curl.
Therefore, once you notice this symptom, take a few minutes to review your plant’s care routine to identify the cause so you can begin treatment.
Why Are My Dieffenbachia Leaves Turning Yellow?
The Dieffenbachia is commonly found in homes because it does well in a wide range of lighting, temperature and humidity conditions. This makes it easy to care for since it can adapt to various environments.
However, its ability to tolerate different surroundings has a limit. And when it is not getting what it needs, its leaves can turn yellow to warn you that it needs help.
Here are the most common causes of Dieffenbachia leaves turning yellow.
Overwatering is the number one reason that Dieffenbachia leaves turn yellow. Therefore, it is the first thing to check. More importantly, because overwatering can have serious consequences, it is important not to put off investigating this potential problem.
Overwatering happens for different reasons. The most commons is when you water the plant too often.
However, other things that can cause overwatering include using soil that retains too much moisture, a pot with insufficient drainage and overpotting.
The problem with overwatering is that it causes soil to become waterlogged. When this happens, the small gaps in the soil are filled with water which prevents air to get to the roots.
As a result, your plant drowns in the water as it is not able to breath.
Since roots need both oxygen and water to stay healthy, the roots eventually sustain damage. Depending on how long they stay underwater and how often it happens, it can quickly lead to root rot, bacterial or fungal disease.
In order to check for overwatering, it is a good idea feel the soil once in a while. If you stick your finger into the soil down a few inches and it is wet or soggy, that means you’re overwatering.
If you suspect that this has been happening for a while, it is always a good idea to unpot the plant and check the roots. Black, brown, mushy and foul-smelling roots mean that root rot has set in.
Should this happen, repot the plant in fresh, dry soil to help it recover. If there is no root rot, allow the soil to dry out and scale back your watering routine.
How to Avoid Dieffenbachia Yellow Leaves Due to Overwatering
The best way to avoid yellow Dieffenbachia leave due to overwatering is to always check the soil before you add more water.
Only add water once the top 2 inches of soil has completely dried out. Avoid doing so before then. If you find that the soil at that depth is still wet or moist, wait a couple of days and check again.
Also, your Dieffenbachia will appreciate deep watering.
This means saturating the soil with moisture when you add water. To do so, keep adding water until you see it start dripping down from the holes at the bottom of the pot.
Then allow the plant to soak the moisture for a few minutes before letting the excess liquid completely drain.
The last step is very important as you don’t want to leave the soil with a lot of water, which is what causes yellowing leaves and potential root rot.
If you have a very busy schedule or sometimes forget to water your houseplants, it is possible that your Dieffenbachia has yellow leaves because it is underwatered.
Although this happens much less than overwatering does, it does occur often with busy individuals who don’t have a lot of free time.
While the Dieffenbachia can tolerate some drought, it will eventually get dehydrated if the soil stays dry for long periods of time.
When this happens, you’ll see its leaves turn yellow or brown with the new and old leaves being the once most affected.
This makes it different from overwatering where most or all the leaves start turning yellow.
Another tell-tale sign of underwatering is in addition to the leaves turning yellow or brown, you’ll notice that they are dry and crispy especially at the tips and edges.
The good news is that the plant will quickly bounce back once you water it. It does not take as long as an overwatered plant to recover. In fact, you should see a difference in the plant’s appearance within 24 to 48 hours.
Humidity is Too Low
Low humidity is another potential cause for your Dieffenbachia leaves turning yellow. It is also related to moisture. Although this time, we’re taking about moisture in the air, not in the soil.
Dieffenbachia enjoy humid environments. Their ideal humidity level is around 60%. And this is where they grow best.
However, the plant will be happy as long as you keep humidity at 40% or higher.
When the air gets too dry, it can turn your Dieffenbachia’s leaves yellow.
Often, this happens when the plant has been staying in a higher humidity location and is suddenly moved to a spot with low humidity. Therefore, it will need time to adjust to its new environment.
As such, don’t be surprised if this happens when you first bring the plant home. That’s because living conditions in nurseries have been optimized for the plants that they grow.
Fortunately, once the plant gets acclimated to its new living conditions, it will usually begin to recover from tis yellow leaves. But if humidity stays too low, you’ll eventually see yellowing or browning of the leaves along with crispy tips and margins.
Therefore, it is a good idea to try to maintain sufficient humidity to keep the plant happy.
Dieffenbachia are generally quite tolerate of different indoor temperatures. That said, it does best in moderate to warm conditions. Its ideal temperature range is between 50 to 80 degrees Fahrenheit.
However, when you leave the plant in conditions that are above or below its ideal range, its leaves can turn yellow. This is usually a reaction to temperature stress.
When thing get too hot or too cold, it will struggle. And the yellow leaves are its way of telling you that it is not well-suited for that climate.
For this reason, the Dieffenbachia grows best outdoors in USDA Hardiness Zones 10 to 12. If you live in these locations, you can keep the plant outdoors all year round and it will be happy with the weather.
Anywhere colder than Zone 10, you’ll want to keep it as a houseplant or bring it back indoors once the weather gets colder around late fall.
Indoors, there are also a few things to watch out for.
- Try to keep temperature indoors regulated especially during hot summers and cold winters
- Avoid leaving it near appliances like air conditioners, heaters, radiators, fireplaces or stoves
- Keep it away from drafts be it cold or hot
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The Dieffenbachia prefers medium to bright, indirect light indoors. Outdoors, it does best in partial shade.
More importantly, it cannot tolerate strong, intense or direct sunlight for more than 1 to 2 hours a day. If it gets this much exposure, its leaves will eventually turn yellow. They also become prone to scorching while the plant can dry out.
On the other hand, try to avoid low light as well. While the plant can tolerate some low light, its growth will slow down.
Past a certain threshold, your Dieffenbachia will become leggy as it will try to reach out towards the light source in desperate attempt to get more illumination.
Low light also means you’ll need to adjust your watering schedule since the soil will take much longer to dry. If not, it can lead to overwatering.
To avoid any issues for lighting, it is a good idea to keep the plant near an east or north facing window. You can likewise place it in a western or southern exposure provided that you keep it away from the sun’s rays.
Finally, you may need to move the plant depending on the time of year. That’s because summers tend to have more sunlight whereas winters have significantly less.
Therefore, depending on the layout of your home’s windows and how much access to natural light they receive, you may nee to adjust the plant’s position so it gets optimal light.
Pests and Diseases
Pest and infections are two other reason for your Dieffenbachia leaves turning yellow.
The most common bugs that tend to attack the plant are sap sucking insects. These include spider mites, mealybugs, scale and thrips.
As these pests rob the plant of its internal juices, they cause yellow patches to form of the leaves. And the larger the pest infestation, the worse the yellow leaves on your Dieffenbachia get.
Therefore, it is important to regularly inspect your plants for pests. These insects like to hide on the underside of leaves and the junctions around the nodes. Because they are tiny, it is important to be thorough when you inspect.
Similarly, bacterial and fungal infections can turn your Dieffenbachia leaves yellow. The main reason these diseases occur is overwatering. Thus, it is a good idea to keep the plant on the drier side of things to avoid them.
Fertilizer plays an important role in keeping houseplants healthy. In addition to helping them grow optimally, it also prevents nutrient deficiencies.
Nutrient deficiencies can cause your plant to grow slowly, have some abnormalities or even deformations. One of the most common symptoms if yellow leaves. In most cases, this is due to lack of phosphorus which is one of the essential minerals in fertilizer.
As such, making sure you feed your plant is important.
That said, make sure to avoid over fertilizing it. Doing so can lead to more serious problems as excess fertilizers will eventually cause toxicity problems that can damage the roots.
For optimal growth, feed your Dieffenbachia using a balanced, water-soluble fertilizer once every 2 to 4 weeks when it is growing. Dilute the dose by half strength to avoid overconcentration.
Finally, there’s natural aging.
I’ve left this for last because this is something that you should not worry about. The reason is that it happens as part of the plant’s natural life cycle. Therefore, there is no problem, and you don’t need to do anything.
One of the reasons that the Dieffenbachia is a popular houseplant is that it has a long lifespan. This lets you keep the plant for a long period of time without having to get a new one for your home.
However, like all living things, it will age and get old at some point.
When this happens, its green leaves will turn yellow. Later on, the leaves will fall.
To encourage new growth, it is a good idea to prune the leaves and stems. This will allow your plant to grow new foliage again.