The Zamioculcas zamiifolia, commonly referred to as the ZZ plant is seemingly indestructible, at least until yours has yellow leaves, that is. I’ll investigate the causes of leaf yellowing and present solutions ahead.
Why do my ZZ plant leaves keep turning yellow? ZZ plant leaves will turn yellow most often due to overwatering. Other cause of foliage discoloration includes nutrient deficiencies or imbalances, pests, dry conditions, and too much heat and/or sunlight.
In this informative guide, I’ll walk you through the above causes of ZZ plant leaf yellowing and share some solutions. By the time you’re done reading, you’ll know exactly how to fix your ZZ plant’s yellowing problem(s)!
ZZ Plant Leaves Turning Yellow – 7 Causes and Fixes
Cause #1 – Overwatering
The ZZ plant (Zamioculcas zamiifolia) is indeed very hard to kill. However, just because an indoor plant is hard to kill doesn’t mean it’s impossible to do it.
One of the fastest routes to premature plant death is overwatering.
Overwatering is when you overdo it on the H2O. The roots of your ZZ plant, which are buried deep in its soil, drown because they’re receiving more water than oxygen.
As the roots drown, they begin to turn brown and then black. They lose their firmness, and the soil as well as the roots commonly begin to smell rancid.
Above the surface of the soil, you may begin to notice that your ZZ plant’s lower leaves have turned yellow. The ZZ plant branches will usually wilt, a sign of being water logged, and any new, emerging leaves could be brown.
Plus, growth of your ZZ plant will slow and even stop completely.
Root rot is one of the most serious plant diseases. Once your ZZ plant has more dead roots than healthy ones, the plant will likely die.
Reversing a case of root rot that has advanced to a point of more dead roots than healthy roots is usually impossible. Trying to revive any plant in such a condition is rarely successful.
The Solution – Water When the Soil Feels Dry and Use Well-Draining Soil
For ZZ plant leaves turning yellow from overwatering, you can learn better care for the future.
You shouldn’t water the ZZ plant until its soil feels dry. Yes, all the soil.
The ZZ plant is considered so easy to care for because you don’t have to monitor how much moisture is in its pot all that often.
You might go as many as two or even three weeks between watering, and that’s normal for a ZZ plant.
I would suggest the fingertip test for gauging how moist the ZZ plant’s soil is. Be prepared to reach your hand pretty far down into the soil, as you want to feel all the way to the bottom.
Further, make sure that the potting soil mix you’ve selected for the ZZ plant is well-draining soil.
You can use standard potting soil but be sure to add plant amendments for aeration such as perlite and even one part coarse sand.
Cause #2 – Nutrient Deficiencies or Imbalances
Imagine if you went through your life without ingesting any vitamins, minerals, and nutrients. You’d be in very bad health, right?
It’s the same case for your indoor plants, including your ZZ plant.
Plants need three macronutrients for survival, which are nitrogen, potassium, and phosphorus.Micronutrients such as chlorine, molybdenum, copper, iron, manganese, zinc, and boron are important as well.
What do these macronutrients and micronutrients do? Together they’re responsible for the developmental growth of the plant. In combination they support overall plant health, mostly by building stronger proteins in the plants.
Macro and micronutrients can be especially important to indoor plants when it comes to helping and assisting them to successfully undergo photosynthesis.
Further, your ZZ plant will grow, as nutrients support the growth of new roots, stems, fruits, and flowers.
An indoor plant with a nutrient deficiency will have leaves that become pale green and then yellow. Browning at the leaf tips may occur as well.
Maybe you’re fertilizing your ZZ plant, but it might be at the incorrect frequency. You could also have purchased an imbalanced type of fertilizer.
When your ZZ plant gets too much nitrogen but not enough phosphorus or vice-versa, then it’s still deficient. The above symptoms would recur.
The Solution – Increase Fertilization Habits, But Not to Excess
More than likely, if your ZZ plant is nutrient-deficient, it’s because you’re not fertilizing this plant at all.
The ZZ plant only requires fertilization very periodically, no more than once per six months. I told you, this plant is quite easy to care for.
You can buy an all-purpose indoor plant fertilizer, but what’s more important is that the macronutrients are balanced.
On the front of the packaging, you should see three numbers expressed as a ratio, like 10-10-10. If one of the numbers on the label is greater than the other two, don’t buy that fertilizer.
It’s not balanced enough for the ZZ plant.
Can you fertilize the ZZ plant more than once per six months? If you’re very eager for yours to grow, yes. However, I would recommend you tread carefully.
You don’t want your plant to develop fertilizer burn. Too much fertilizer or “fertilizer burn” causes effects similar to what would happen if you left your plant out in the sunlight for too long. I’ll tell you more about that later.
For more information on over fertilizing indoor plants, you’ll want to read my article: How to Fix Using Too Much Miracle-Gro on Your Plants
Cause #3 – Pest Infestation
As easy as it is to water and fertilize the ZZ plant, this plant does have its downsides. For instance, pests find the Zamioculcas zamiifolia attractive.
The full list includes fungus gnats, mealybugs, scale insects, whiteflies, spider mites, and aphids.
Here is an overview of each bug species.
- Fungus gnats: The fungus gnat has a short life but can still wreak havoc while it’s alive. The gnats dig deep into potting mix and soil, limiting the growth of your ZZ plant or other plants in your indoor garden.
- Mealybugs: Favoring warm and moist environments, mealybugs are unarmored and hungry for the juices of plants such as your ZZ plant. They can’t fly, but they can spread across a plant easily.
- Scale insects: Scale insects can propagate on an indoor plant like the ZZ plant almost effortlessly, causing yellow leaves, early leaf drop, and twig and stem death. Brown blemishes across your ZZ plant’s leaves may also appear.
- Whiteflies: A relative of the mealybug and aphid, whiteflies are small, winged insects with soft bodies. In warm weather, they’ll emerge to drink the sap of your indoor plants.
- Spider mites: More than 1,000 spider mite species are out there. When they appear on your ZZ plant or other plants in your indoor garden, they’ll live on the underside of the plant’s leaves. Usually discovered by noticing tiny webs along the length of the leaves.
- Aphids: A more common insect to invade your indoor garden, aphids can be wooly or smooth, and they come in a rainbow of gross colors. They’re also thirsty sap drinkers and can wreck your ZZ plant.
The Solution – Know the Signs of Pests and Remove Them
How do you know whether your ZZ plant has an insect infestation?
I’d recommend checking underneath the leaves first. As mentioned, in the case of spider mites, they’ll weave white webs across the leaf.
Mealybugs and aphids produce honeydew. No, not like the fruit. This version of honeydew is a waste product. The honeydew is slick and sticky.
You can sometimes even see a species of bugs if they’ve clustered in large numbers.
If you don’t spot insects on your ZZ plant, that doesn’t mean they’re not there. Many of the above species are very hard to detect, especially in the early days of an infestation.
You’ll have to do the process of elimination. If you’re not overwatering your ZZ plant and it’s still turning yellow, and you’re sure its fertilizer is good, then it could be an insect invasion.
Here’s some good news. Removing these insects is usually very easy. You can typically use water and dish soap or rubbing alcohol.
Sometimes you can even flick the bugs off or spray them with a garden hose.
Of course, your ZZ plant will be considerably weaker if the plant survived a major infestation. Be sure to monitor your plant in the weeks to come and continue with proper care.
If your plant were to get sick or injured now, it might not survive.
Cause #4 – Overly Dry Conditions
The ZZ plant is drought-resistant, but it’s not a succulent.
It cannot store water in its leaves for a later date. It has to use what you give it when you provide it.
When you go too long without watering your ZZ plant then, what do you think will happen?
It will begin to dry out, of course.
Its tall, proud leaves will become droopy and saggy. The leaves will turn yellow across the entirety of the plant, and you might see some brown leaf edges as well.
The Solution – Don’t Forget to Water Your ZZ Plant! Check Humidity Too
Going back to what I mentioned before, you should only water the ZZ plant when all its soil is dry.
Try not to forget to water it too much longer after it reaches that point. If you do, you’ll come home one day to a yellowed, wilted, sad ZZ plant.
Indoor plants don’t only get moisture from the water you pour into their pot but from the air as well.
The ZZ plant doesn’t have special humidity requirements. If the humidity in your home or office is at about 40 percent, this plant will be fine.
The average relative humidity in a building can be as low as 30 percent and up to 50 percent. I’d recommend investing in a hygrometer so you can determine how much moisture is in the air where you’re growing your plants indoors.
Here’s a link to the hygrometer I’ve been using for the past 3 years, available on Amazon.
If it’s less humidity than what the ZZ plant requires, use a humidifier on your plant.
Cause #5 – Inconsistent Watering
When you first brought your ZZ plant home, you cared for it very well.
As time goes on and you add to your indoor garden, you’ll admit that sometimes your ZZ plant has been forgotten. It’s shown you that it can handle it, so you don’t stress too much about it.
Well, switching between regular and intermittent care is not good for Zamioculcas zamiifolia.
In other words, you shouldn’t forget to water this plant for weeks and then start watering it every day. It’s also not good to water the plant regularly and then stop for long periods.
You might notice wilting and foliage yellowing in both situations. On top of that, watering too often, as you’ll recall, can lead to root rot.
The Solution – Use a Phone App to Remind You to Water Your Plants
Listen, everyone is busy these days, many of us too busy. It’s okay if you forget to water your plants from time to time. You’re only human, after all.
If forgetting to water your plant is becoming a regular habit though, you might want to download an app on your phone to remind you when it’s time to water your plants.
Cause #6 – Too Much Sunlight
The ZZ plant doesn’t mind living in dim conditions so much. Will you see a lot of growth out of the plant? No, but it will live.
That logic does not apply to bright conditions. When you put the ZZ plant in direct sunlight or “full sun”, the sunlight is going to scorch your poor plant.
The leaves may be yellow for a spell, but they’ll quickly become brown and even black.
You’ll know that you’ve overdone it on the sunlight because the leaf texture will become crispy and dry.
A sunburned plant may be saved. You’d have to bring it into cooler, dimmer conditions and assess the state of the leaves.
You’ll have to prune the browned and blackened bits of your ZZ plant, as they will never turn green again.
The Solution – Provide Bright, Indirect Light
In the dim light, the ZZ plant survives, but in bright, indirect light, your Zamioculcas zamiifolia thrives.
Bright, indirect light requires a curtain to act as a medium between the sunlight and your plant. A northerly-facing window never gets direct sun, which makes it a viable option for positioning your ZZ plant.
Cause #7 – Heat Stress
The ZZ plant is a lot of things, but one thing the ZZ plant is not is heat-tolerant.
When the temperatures begin to climb, your plant will get dehydrated. This isn’t all that different from how you feel when you’re outside on a sweltering summer day.
If the ZZ plant continues to be exposed to excessive heat, it will likely begin showing signs of sun overexposure.
That’s right, everything from leaf yellowing to crisping and even leave blackening is due to over exposure to the heat.
The Solution – Monitor Temperatures at Home or Work; Don’t Forget Other Sources of Heat
At temperatures between 65 and 75 degrees Fahrenheit, the ZZ plant is happiest. This is standard room temperature, so it should be easy enough to provide the ZZ plant with the right temps.
At home, you have control over the thermostat, but that might not be the case at the office. Consider taking your ZZ plant home with you if you know that your office turns off the AC after working hours.
Be considerate of other sources of heat as well. For example, if your ZZ plant is by a return vent in your living room, then the plant will be exposed to high heat all winter when the furnace is on.
Keep your zz plant away from large appliances such as your refrigerator, as they often have heating elements that emit large amounts of heat as well.
