Fungus infection is the primary cause of black spots on the ZZ Stem. It can also be caused by bacterial or other pathogens, as well as physical injury to the plant's stem.
Overwatering is another reason for this problem, as it can cause the roots to rot, which puts excess moisture into the ZZ Stem itself. It also allows fungus development, as damp conditions are ideal for fungal growth.
But there are ways to revive the plant from black spots. I have shared some useful solutions and insights on this problem. So, let's get started!
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What Are Black Spots On ZZ Plant Stems?
For several reasons, black spots can appear on your ZZ plant. The most likely reason is the nasty fungus attack. Since the ZZ plant is susceptible to these issues, you shouldn't be too surprised to see these spots on your plant.
But then, there are other possibilities as well. So, take a quick look at the root cause of this issue in your plant.
1. Overexposure To Direct Sunlight
Have you kept your plant in direct sunlight or near a window? If that's the case, you might see black spots on your ZZ plant.
In case you don't know, the ZZ plant doesn't like sunlight much. Despite being a desert plant, it is averse to receiving too much light. So, whenever the plant gets exposed to such a type of light, it will show signs of black spots and yellow leaves on the stem.
If you don't address this issue quickly, the plant will not be able to survive for more than a few weeks. In this case, you will have a limited time to fix this problem.
2. Overwatering
It is the only thing that makes things difficult to grow indoor plants at home. When you overwater the plant, it can attract a whole lot of issues. Like the sunlight issue, the ZZ plant is also averse to overwatering.
Since it stores its water and nutrients in the bulb, it doesn't require much water from outside. It's typical of a desert plant, as it receives much less water through natural resources in those conditions.
If you overwater this plant, it will cause the roots to rot. Ultimately, the root rot will spread to the entire plant. This is why you might see black spots or patches on the stem of this plant.
3. Black Fungus
As I mentioned earlier, the black fungus can also attack the ZZ plant.
Source - Reddit
When the plant sits in the water for quite some time, the wet soil can become a breeding ground for this fungus. Once the fungus grows on the topsoil, it quickly moves to the stem.
When it targets the stem, it makes it weaker and leaves black spots or patches on its surface. If it continues to spread, it can weaken the whole plant and will make it difficult to survive in the end. Hence, it needs to be addressed quickly before it can damage other important parts of the plant.
So, is there any way to fix this problem in the ZZ plant? Let's learn more about it in the next section.
How To Fix Black Spots On ZZ Plant Stems
Even though the following fixes help greatly solve this issue, you won't be able to remove the black spots from the stem completely. These are permanent marks and may remain on the stem till the end of the plant's lifecycle.
You can only prevent them from spreading further. Moving on, here's a list of things you can do to prevent and fix the black spots issue -
1. Move Your Plant To A Shaded Place
As I explained earlier, this plant doesn't like direct sunlight.
Therefore, it makes sense to move it to a place where it will be far from natural sunlight. You can keep this plant in a shaded place in your home. These types of places are quite good for the ZZ plant. It will continue to thrive in these locations if you take care of the plant.
As for the black spots, they may not disappear completely from the stem. But you will surely not see more spots once you move the plant to the shaded place.
While moving the plant to this type of place, ensure there is not much humidity in the room. The plant will struggle to do well if there is too much humidity in the room. Also, it might attract more issues to the plant.
2. Limit Watering Your Plant
The ZZ plant doesn't require too much water, either.
You should only water it once or twice a month. This is the right frequency for watering this plant. If you add more water than this frequency, the bulb of the plant will begin to rot.
Once it begins to decay, it won't function properly, and the topsoil will remain wet for a long time.
To avoid this situation, you should stop watering this plant for a while. If you are not sure when to water this plant, you can simply touch the topsoil or lift the pot if it's a small pot.
Both these techniques will give you an idea about the water content in the soil. With this assessment, you can plan your watering frequency accordingly.
ZZ Plant Watering Schedule:
| Weather Conditions | Watering Frequency |
|---|---|
| Summer | Once A Week |
| Winter | Once A Month |
| Rainy | Once A Month |
3. Keep The Soil Dry In The Pot
Since most fungus issues arise from the soil, you should aim to keep it dry all the time. This way, you will greatly prevent and stop the fungus growth on your plant. More importantly, it will prevent it from spreading to other plants in your garden.
But what do you do when the soil is already wet? In this case, you can scrape off the topsoil and replace it with some dry soil.
4. Do Not Mist Your ZZ Plant
I know many of us like misting our plants regularly, but it's not a great idea for the ZZ plant. It cannot tolerate excess water in any form.
So, if you have a habit of misting your garden plants every morning or evening, you should skip this plant entirely. Otherwise, it will make things worse for this plant, and you won't be able to revive it in the end.
5. Spray Fungicide On The Affected Stems
The fungicide is the best thing you can use to fix the fungus on your ZZ plant stem. Once you confirm this issue on your plant, you can spray some fungicide solution on the affected parts of the plant.
For fungicides, you can choose any available products in the market. The neem oil also works great against this issue, so you can also use it.
Note: You will have to spray the plant a couple of times, as there is always a possibility that it might resurrect in the future. When you are done spraying, you should isolate the plant from other plants in your indoor garden.
6. Keep Your Plant In A Well-Ventilated Space
Lastly, you should find a place in your house that is nicely ventilated. A well-ventilated place will keep your plant dry for a long time.
Even if you water it heavily occasionally, it won't cause much of an issue to the plant. If the room is airy, the excess water will evaporate quickly.
So, these are the things you need to do to stop the black spots on the ZZ plant stem. Do try out these fixes and see how they work on your plant.
FAQs
The roots will appear dark if you remove the pot from the pot. You may also smell a rotting odor from the pot, which is another indication of root rot in the ZZ plant.
Along with this, the bulb and roots will turn mushy due to excess watering. These are the few signs through which you can identify the problem in your plant.
The ZZ plant stem can turn brown because of underwatering and direct sunlight. You should also refrain from overfertilizing this plant.
The ZZ plant can grow new stems if you offer ideal conditions and nutrients. Generally, the plant produces a couple of new shoots every few months.
As suggested in the guide, this plant is averse to excess sunlight. You should never keep it in direct sun.
The ZZ plant can recover from overwatering, though it all depends on the condition of your plant.
If the stem and leaves look fresh, you will have a greater probability of reviving this plant. It would help if you thought of transplanting the plant into a newer pot with fresh soil mix for the revival process.
Over To You
Fixing the black spots on ZZ plant stems can be challenging for new gardeners.
Firstly, you will have to identify the cause of this problem. Then you need to decide how you want to deal with the situation.
If you have any queries on this process, please let me know in the comments. I will try to resolve them for you. In the meantime, do share this guide with your friends and family if you found it helpful.
References: University of Nebraska–Lincoln, University of Florida
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