5 Causes of Brown Spots on the ZZ Plant Stems [Fixing Guide]

If you are someone who forgets to take care of their plants then ZZ plants are the best gift for you. Because they require no extra care, they can thrive in low lights and you can forget about watering them too. 

But if you see there are brown spots on the stem, it means something is not right. ZZ plants are very tolerant to many factors. But when a certain problem occurs,  they always cannot recover on their own. So if you take a little time out of your life to solve their problems they will return the favor by enhancing the beauty of your home. 

It’s important to know why the brown spots are on the stem of the ZZ plant so that you can prevent them from happening in the future.  Knowing the reasons behind the brown spots will also help you pick the right treatment for your plant.

Overwatering, Too much sunlight, Lack of nutrients, Root rot, and Poor soil conditions are the 5 big problems that cause brown spots on your ZZ plant stem. 

Don’t worry! There is a solution to every problem. Keep going through the article and find out how you can save your ZZ plant from having brown spots.

So, let’s walk you through the whole process-

Why Are There Brown Spots On The Stem Of ZZ Plant?

1. Overwatering

ZZ plants have rhizomes that store water for them. So, they can live without water for a long time. But if you water it too much the rhizomes will start to rot. And It can even end up killing your ZZ plants.

The early symptoms of overwatering are brown spots on the ZZ plant stem. If they are overwatered continuously the brown spots will get bigger. Eventually, the whole stem will turn brown or black. In addition, the leaves will be yellow and they will start wilting due to excess water.

You have to avoid overwatering your ZZ plant at any cost because overwatering is one of the main causes of root rot which normally kills the ZZ plant within a few days. 

Control Measure

The obvious solution is that you have to reduce watering. When you see the stems are having brown spots with the soil being soggy, it means you have overwatered them. In this case, stop watering your ZZ plants until the soil becomes dry. 

If the soil doesn’t seem to dry soon and you don’t want your plant to suffer anymore, you can change the soil of the pot. Choose a pot that has holes in the bottom of it so that whenever you water them excess water can drain completely out of it. 

Now you might be wondering when and how much to water? 

Water them once in 2-3 weeks inspecting the soil condition. During the cold season water once in 4 weeks.  And the amount of water will change with the weather, plant size, and pot size. So, It’s best if you get a moisture meter that will tell you whether your ZZ plant needs any watering(Our pick: Atree Soil Soil Tester Kits with Moisture, Light, and PH Test for Garden).

2. Too Much Sunlight

ZZ plants don’t survive well under direct sunlight. This is why they are so popular for growing inside the house. They prefer shade with 3-4 hours of indirect sunlight. If your ZZ plants are exposed to direct sunlight for a considerable period the stems will get black or brown spots on them.

Too much exposure to sunlight will burn the leaves and turn them yellow. And the plant will try to get away from the light. As a result, the plant will weaken and bend at some point resulting in breakage of the stem. 

Control Measure

Relocate your plant away from the light source. Don’t put it near any window where they can get direct scorching sunlight. Rather, keep them in a shaded corner of a room that gets bright sunshine.

If too much light is the problem then after putting it under shade, your ZZ plant will take some time to recover. But the stem and leaves that have brown spots on them will not go back to their normal self. You can cut off the yellow and spotted leaves from the plant to make room for new healthy leaves to grow. 

3. Root Rot

Root rot is a very dangerous fungal disease of the ZZ plant that causes brown spots on the stem. Root rot usually occurs due to over-watering and soggy soil. 

ZZ plants have rhizomes that store water underground. So, the ZZ plant can use their stored water as much as they need. This is why they don’t need extra watering.

But when they are overwatered the roots start to rot. As a result, the injured roots do not get to supply proper water and nutrients to the rest of the plant. And this results in brown spots on the ZZ plant stem. Moreover, the leaves start to wilt and get brown or black spots.

Remember that root rot is a fatal disease of ZZ plants. So, whenever you see brown spots on the stem you have to inspect whether your plant is suffering from root rot so that you can start to treat them at the earliest. 

Control Measure

To be sure of root rot, you have to pull the plant out of the container to check the roots. If the root looks black or grey and mushy with a bad smell then you can be sure it’s root rot. 

After that, you have to repot your ZZ plant in a freshly mixed soil mixture. Because root rot is caused by a soil-borne fungus. So, you have to get rid of the old soil. Now, use a good fungicide that is suitable for houseplants (Our Pick: Bonide Copper Fungicide). Always follow the instructions on the label of the fungicide so that your plant gets the right dosage. 

Remember to choose a container that will drain the extra water very quickly. Replant the ZZ plants in a slightly larger container. If the container is smaller than the roots, it cannot grow properly and fall victim to root rot again. 

Try some homemade remedies of root rot that will help you control this disease more naturally:-

#Recipe 1:-Garlic Pepper Fungicide Recipe


  • I bulb of garlic
  • 1 tablespoon of canola oil 
  • 4 hot peppers
  • Juice squeezed from one lemon


  • Mix all the ingredients together
  • Steep this mixture overnight
  • Strain the mixture with a cheesecloth 
  • Mix 1 tablespoon of this mixture with every liter of water 
  • Apply it to your ZZ plant 2 times every week

Caution: Carefully handle the mixture. Because it contains pepper that can irritate the skin and eyes. 

#Recipe 2:- Baking Soda Fungicide Recipe


  • 3 teaspoons of baking soda
  • 2 tablespoons of vegetable oil
  • 4 liters  of water
  • 1 teaspoon of liquid dish soap


  • Mix everything and give a good shake
  • Spray this solution on the infected leaves and stems of the ZZ plant 

Note: All the homemade recipes may not suit well with your ZZ plant. For this, try a little amount of the homemade fungicide in a small leaf and wait out for a few hours to see the reaction. If the leaf seems okay then apply the fungicide to the rest of your ZZ plant.

4. Lack of Nutrients

This is not very common but still sometimes when the ZZ plants lack nutrients, their stem gets brown spots. You see, the ZZ plant containers have a limited amount of soil so after a few years, most of the nutrients get used up. And the plant starts to show symptoms.

There are many kinds of nutrient deficiency. Among them, nitrogen and iron deficiency causes brown or yellow spots on the stem. 

Control Measure

Feed your ZZ plant a moderate dose of balanced fertilizer once every spring. The houseplants need a different dose than other garden plants. If you use any lawn fertilizers on them, the roots of your plants can burn.  So, pick the best houseplant fertilizer for your ZZ plants (our pick: Aquatic Arts Indoor Plant Food).

Water them right after giving fertilizer. So that it will mix with soil uniformly. ZZ plants aren’t much of a feeder. But you can try giving a small amount of fertilizer diluted in water if you see brown spots on the stem. 

If you want to give some homemade fertilizer to your ZZ plant then here are the recipes: 

#Recipe 1:- Banana Peel Fertilizer Recipe

  • Dry the banana peels under sunlight. They will turn completely back and crispy
  • Turn  them into powder in an electric mixer and store the powder in an airtight container
  • Take a few spoonfuls of the powder and mix it with the soil
  • Water lightly after applying the homemade fertilizer so that it can mix uniformly with the soil

#Recipe 2:- Egg Shell Fertilizer Recipe

  • Collect the eggshells from the kitchen and wash them very thoroughly and remove the membrane present underneath the shells
  • Dry them completely under the sunlight 
  • Now use an electric mixer to turn them into powder
  • Put a few  teaspoons of this powder in your ZZ plant container and water lightly after that

5. Poor Soil Condition

This is a very important thing to discuss. Let’s start with a scenario where you have been watering your ZZ plant very carefully. You have also placed them in a perfect spot where they are getting a suitable amount of sunlight. But still, your ZZ plant has brown spots on the stem. Wonder why? 

This is happening because you have planted them in the wrong kind of soil. ZZ plants are succulent-type plants. That means they need soil that is a bit sandy.

Clayey soil holds water for a long time which is not good for them. Moreover, clayey soil does not drain water quickly. Both the reasons cause fungal diseases to ZZ plants. So, the bottom line is, you have to plant them in sandy soil with good organic matter. 

Control Measure

Use a good potting mixture especially made for succulents (our pick: Miracle-Gro Indoor Potting Mix). Or you can make a soil mix by yourself by adding sand or perlite with the soil.

If you suspect that the soil is very compact then it’s probably putting pressure on the roots. In this case, change the soil and replant the ZZ plant in fresh soil. After a few days, the plant will start to recover. 


Sometimes physical damage can cause brown spots on the stem. The stems of ZZ plants are soft and delicate so you have to be careful while handling them. In this case, the plant will recover naturally if it’s not too damaged.

The ZZ plants don’t ask very much from you. Just keep it in a dark place, water them very little, protect them from root rot. Your ZZ plant will be thriving within a few days.

In this article, I have explained why the ZZ plants get brown spots on the stem and how you can get rid of them. I hope this article was helpful to you while treating your ZZ plants with brown spots. If you have any further queries feel free to ask in the comments. 

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