Why Are Dieffenbachia Leaves Turning Yellow: Causes & Solutions
Yellowing leaves is a common problem with Dieffenbachia. It can affect the plant’s overall health and appearance. There are several reasons why this may happen, including overwatering, underwatering, pests, diseases, low humidity, nutrient deficiencies, lighting issues, and temperature extremes.
If you notice yellowing leaves on your Dieffenbachia plant, don’t worry! In this post, I will help you identify the cause of yellowing leaves on your Dieffenbachia plant and provide you with solutions to fix the problem.
1. Overwatering or Underwatering
Incorrect watering is the most common cause of yellowing leaves in many houseplants, and Dieffenbachia is no different.
This plant prefers moist soil with time to dry out between waterings to prevent it from sitting in water for prolonged periods. If the roots are sitting in water, they can’t breathe and will suffocate. This will limit the flow of nutrients and water to the leaves.
However, if the soil is too dry, the plant can’t absorb nutrients because they are ingested through water, which can cause yellowing.
It can be tough to tell if you are under or overwatering, especially when the symptoms are similar, as with yellowing leaves. Yellow leaves that are soft and drooping indicate overwatering, while underwatering will cause yellowing along with a dry, brittle edge.
What you should do:
Assess the pot and soil your Dieffenbachia is sitting in.
Is the soil too wet or too dry?
Soil that holds too much water will contribute to overwatering, while too dry soil will cause underwatering. If you’re not sure which soil you should use for your Dieffenbachia, read our guide here: Choosing the Best Soil for Dieffenbachia (3 Recipes That Work)
The pot should have drainage holes and be placed on a dish to catch the excess water and allow it to evaporate.
Those elements are essential, but a regular watering schedule is key to this problem. I suggest setting a time and day every week that you water your plants because erratic watering can also cause leaves to turn yellow.
Watering once a week should be sufficient, but you can increase this to twice a week during the summer for larger plants. Before watering, insert your finger into the soil and feel the moisture level. The soil should be dry at least an inch below the surface before watering.
Keep in mind that plants in smaller pots will have to be watered more frequently than in large pots with plenty of soil to retain moisture.
2. Diseases
One disease directly caused by the overwatering we discussed above is root rot. This is the most common disease that affects Dieffenbachia, and it is caused by a fungal infection that comes about when the plant is sitting in wet soil.
A combination of factors can indicate that root rot is your issue:
- Test the soil to see if it is wet.
- Smell the soil close to the base of the plant. If there is a slightly moldy odor, it can indicate rot.
- The yellow leaves will be droopy and soft.
They are also susceptible to rust, orange spots, and powdery mildew, white patches on the leaves that will appear along with the yellowing.
What you should do:
If you suspect root rot, remove your plant from the pot and inspect the soil. Remove the waterlogged soil and gently cut away any rotten root material with pruning shears until only healthy roots remain.
Ensure you sanitize your pot before reusing it to eliminate any remaining fungus.
Repot in fresh, well-draining soil in a pot with drainage holes and implement a watering schedule as I described above to avoid overwatering again.
You can treat rust or powdery mildew with a fungicidal spray. It should be sprayed on the affected leaves every 3-4 weeks until the issue clears up.
3. Pests
If there are many yellow spots and damages randomly on your Dieffenbachia’s leaves, your plant may have pests. The main pests that affect this plant are spider mites, mealy bugs, and scale, which all leach the sap out of the leaves to steal the nutrients.
Luckily, pests are easy to identify when diagnosing your Dieffenbachia’s yellow leaves. All the pests I mentioned are visible on your plant or leave behind secretions that indicate their presence.
How to identify pests:
Check both sides of your leaves and down the stem. Keep an eye out for insects on the surface of the soil.
- Spider mites: Small reddish-brown bugs on the leaves
- Mealybugs: Cotton-like excretions on or under the leaves
- Scale: Scaly-looking patches across the surface of the leaf
What you should do:
When dealing with pests, the first step is to isolate the plant to prevent them from spreading. More minor infestations can be washed off with water, but for more extensive issues, I like to use neem oil.
You can buy a premade mix or mix your own by combining 2.5ml neem oil and 2.5ml liquid soap with a gallon of water. Mix well, decant into a spray bottle, and spray the plant once a week until the pests are gone.
I also suggest carefully inspecting any plants near your Dieffenbachia in case they have also been affected.
4. Natural Aging & Seasonal Changes
Some leaves will turn yellow with age or the changing of seasons, which is perfectly natural. This commonly happens during autumn and winter. If your plant displays no other signs of distress, as we have detailed here, this might be the reason for the yellowing, and it’s nothing to be concerned about.
You can tell that the yellowing leaves are simply aging because only the lower few leaves will be affected, while the rest of the plant remains healthy and produces new leaves.
What you should do:
Wait for the leaves to soften enough to gently remove by hand, and then pick them off. Pop the leaves into your compost bin so they don’t go to waste.
5. Nutrient Deficiency
Dieffenbachia thrive in nutrient-rich soil. The nutrients help maintain the beautiful variegated pigment on the leaves, so when they are lacking, the leaves will go yellow.
A deficiency could be caused by the type of soil you use, lack of fertilizer, underwatering, or the plant being root-bound and unable to absorb nutrients sufficiently.
What you should do:
Check if your plant is root-bound by removing it from its pot and inspecting the roots. If it needs more room, transfer it to a new, large pot filled with a well-draining potting mix with plenty of perlite and peat moss.
Dieffenbachia is one of those houseplants that loves a regular dose of fertilizer. Still, I recommend using it at half strength to prevent over-saturating the soil. Fertilize every 4-6 weeks in summer and 8-10 weeks in winter while it’s dormant. Be careful not to overfertilize, which can burn the leaf’s edges and cause yellowing.
6. Temperature Change and Lack of Humidity
The Dieffenbachia doesn’t only require an even watering cycle but also a consistent temperature. This plant is relatively easy to take care of. Still, it doesn’t like its living conditions changing and will display its unhappiness with yellow leaves. This plant is at its happiest around 65-75 F.
Similarly, this plant enjoys a little humidity so that it can benefit from a mist every now and then. The leaves will yellow from low humidity because it will cause excessive moisture loss that the water in the soil can’t make up for. If you have space in your bathroom, Dieffenbachia is an excellent plant to grow to get some humidity from the shower. Ideally, they enjoy around 60% humidity.
FURTHER READING: How To Increase Humidity for Houseplants (Complete Guide)
What you should do:
The best solution to this issue is choosing a good spot for your plant and keeping it there. That way, only the seasonal temperature changes will affect it. Choose a location away from drafts, vents, or fans so the air temperature stays as even as possible throughout the seasons.
7. Too Much Light or Lack of Light
Dieffenbachia plants love partially shady spots where they can get a few hours of bright, indirect sunlight per day. Their natural environment is in a jungle, so they are used to having their light sources interrupted by other plants.
If it gets too much sun, the leaves can quickly turn yellow and maybe even develop brown, crispy patches on the leaves. The excess warmth can also affect evaporation, throwing off your carefully planned watering schedule.
When a Dieffenbachia doesn’t receive enough light, it can’t produce enough chlorophyll, which is responsible for giving leaves their green color. As a result, the leaves turn yellow, lose their color, and drop off the plant.
What you should do:
Just as with temperature change, this problem is solved with the proper placement. Try moving your plant to a brighter location or supplementing with artificial light.
I like to place my Dieffenbachia in an east-facing window that gets a few hours of bright indirect sunlight daily while remaining away from drafts.
FAQs
Should you remove yellow leaves from a Dieffenbachia?
It’s best practice to remove yellow leaves because once they’ve lost their color, they can’t recover and will be wasting resources. I recommend waiting until the leaves become soft enough to be gently teased off by hand. This will limit the plant’s exposure to bacteria, which can infiltrate leaves cut with pruning shears.
Why do my Dieffenbachia leaves have brown tips?
This is caused by excessive fertilizer, inconsistent watering, or lack of humidity. See my advice above for setting up a regular watering and fertilizing schedule to resolve this issue.
How often should I water my Dieffenbachia?
As you can see, overwatering and underwatering are both issues that cause yellowing leaves, so it’s essential to get your watering schedule right. Larger plants should be watered twice a week during warmer months, but once a week is sufficient for smaller plants or during the winter months.
