Black Spots on Hoya Leaves – Causes and How to Fix It

Imagine yourself one day after office you start admiring your lovely garden or indoor plant when all of a sudden you observe something quite strange!

A black spot on a leaf, followed by a patch covering the entire plant. The very last image we want to see on the leaves of our lovely houseplant are any black spots.

Though certain plants are more vulnerable to the problem, it is not unusual. Don’t stress because in this article we will help you in finding the potential causes of black spots on your plant leaves and the most effective treatments available. So you can enjoy the beauty of your plant for as long as it shines. Keep reading till the end!

It has been 11 years since I started blogging about gardening. During that time I have also published several blogs about hoya plants and helped hundreds of others grow them. Similar to brown spots, black spots were a big problem for hoya growers. I know it’s the last thing any gardener wants to see black spots on hoya beauty. Therefore, in this article, I will go over all the reasons why black spots appear on hoya leaves and how to fix them. In the end, you will learn how to keep your hoya in good condition so you don’t get black spots.

Wondering why black spots happened in the first place?

Wondering why black spots happened in the first place?

Black patches on houseplant leaves are typically the result of insect damage or a fungus infection. Additionally, overwatering should indeed be ruled out. Aging, bacterial or viral illness, and food insufficiency are less common reasons. Before treating, address care concerns, isolate, and remove affected leaves.

Black spots shouldn’t be accepted, but they also don’t always predict death for your plant. The condition typically appears to be worse because the affected leaves frequently continue to function and don’t truly die. 

The unattractive patches can range in size, some have rounded borders while others have uneven ones. Once the reason is resolved, spots on afflicted leaves are unlikely to return, but they won’t emerge on new leaves. 

Don’t disregard the problem because there are several major causes of black patches. Discovering the issue is essential since treatment differs depending on the problem’s origin.

What Gives Hoya Leaves Black Spots, and How Do You Fix Them?

The appearance of black spots on the leaves of your Hoya plant might occur for several various causes. The most frequent causes are bugs, fungi, and overwatering.

With a few easy adjustments to your plant’s care regimen, the majority of these issues may be resolved. To effectively address the issue, it is crucial to figure out what is causing the black spots on your Hoya leaves.

I have listed below some possible causes of black spots on Hoya leaves, along with solutions for each issue:

1. Overwatering

Homeowners or beginners like us, frequently overwater their plants.

It is caused by giving your plants too much water or watering them too frequently. Additionally, it might happen if the potting soil is overly dense or if the container lacks adequate drainage. 

As a result, the roots become soaked and unable to get the oxygen they require to survive. Numerous issues, including yellowing foliage, wilting, root rot, and finally death, can result from overwatering.

Overwatering may occasionally result in fungal illnesses that generate black patches on the leaves. Fungi can flourish in an environment where the soil is very moist. After that, the fungus spores into the air, which may fall to the ground and form black stains on the leaves.

How To Treat Overwatered Hoya Plant

  • The initial step you should take if you believe your plant is being overwatered is to stop providing it with more water. 
  • Do not water your overwatered plant. Before watering again, let the soil entirely dry out. 
  • Start by removing the plant from its pot and remove any yellow or dead leaves.
  • Look for rottenness in the form of blackening or mushiness at the roots. 
  • Trim the Hoya’s damaged roots, then transplant them into new, well-draining potting soil.
  • Wait until the soil feels dry to the touch before watering the plant again.

2. Fungal Diseases

If you ask me personally, I hate this fungal issue.

Another frequent issue that can result in black patches on Hoya leaves is a fungus disease. Black spot fungus, stinky mould, leaf spot, and anthracnose are a few of the fungi that can create black spots on Hoya leaves.

Now, I will discuss the different types of fungus and bacterial issues that can affect your hoya plants making black spots on them!

a) Black Spot Fungus

Hoya leaves get black patches due to the fungus known as black spot (Diplocarpon rosae). Small, black patches on the plant’s leaves are caused by this fungus. The spots ultimately enlarge and group, turning the leaves yellow and forcing them to fall off. Hoya plants grown in moist or humid environments are more likely to develop black spots.


If the black spot fungus has already attacked your plant, you need to cure the issue right at once. 

  • Start by removing and discarding any damaged leaves using a pruning scissor. 
  • To stop the fungus from spreading, be sure to sanitize your pruning equipment both before and after usage. 
  • Neem oil is a natural fungicide that you may use to treat the plant. 
  • This neem tree oil is used to treat several fungi-related illnesses. 
  • You may either apply it straight to the plant’s leaves or mix it into the potting soil at the plant’s base. 

Am I the only one who thinks neem trees are worthless right now? They are undoubtedly useful.

b) Black mould

A particular kind of fungus called sooty mould develops a black covering on plant leaves. It frequently grows on hoya plants that have insect or scale insect infestations.

These bugs produce honeydew, a sticky material that the sooty mould fungus feeds on. The plant’s leaves then become black as the fungus spreads and covers them. Sooty mould can limit the plant’s capacity to photosynthesize. Let’s be honest, they make your plant look unattractive.


  • Controlling the insects or scale insects that are infesting your plant is the best technique to treat sooty mould. 
  • Use your hands or a cotton swab dipped in rubbing alcohol to get rid of any bugs you observe. 
  • Neem oil or horticultural oil are two more insecticides that you might use to treat the plant. 
  • To protect your plant from damage, make sure to strictly adhere to the label’s recommendations. 
  • Additionally, remove any leaves with sooty mould by pruning them away. To stop the fungus from spreading, dispose of the affected leaves.

c) Bacterial leaf spot

Black stains on Hoya leaves can also be caused by a fungus called leaf spot. If left untreated, this fungus, which is typically brought on by excessive moisture on the leaves, can spread swiftly. A fungal disease called leaf spot may harm a wide range of plants, including trees, bushes, ornamental plants, and flowers.

Regardless of the type of plant that is afflicted, leaf spot symptoms frequently involve tiny, black spots on the leaves. In extreme situations, the leaves may change color and drop off early, turning yellow or brown.
Leaf spot can kill plants if it is not treated, and they can also do substantial harm.


  • It is essential to respond right away if you believe that your plant has a leaf spot.
  • Start by removing and discarding any damaged leaves using a pruning saw. 
  • To stop the fungus from spreading, be sure to sanitize your pruning equipment both before and after usage. 
  • After that, you can apply a fungicide to the plant, like neem oil or horticultural oil.
  • To protect your plant from damage, make sure to strictly adhere to the label’s recommendations. 
  • Additionally, make sure that you water your plants from the base up rather than just misting the foliage. 
  • This will aid in lowering the humidity surrounding the plant and make the environment less conducive to the growth of the fungus.

d) Anthracnose

Hoya is vulnerable to the fungus disease name Anthracnose, which can infect a range of plants. The fungi that cause Anthracnose can exist in soil or on the outside of plant stems and leaves. 

Normally, they penetrate plants through wounds or naturally occurring holes like stomata. The fungus starts to develop and release spores after they have entered the plant. New diseases can then be brought on by these spores when they disperse to other areas of the plant or other plants. 

On plants, Anthracnose frequently appears as small, black lesions. Eventually, the lesions may cause the leaves to droop, curl, and fall off. Anthracnose can destroy the entire plant in extreme circumstances.


You must act right away if you think your plant may have anthracnose. 

  • The damaged leaves should be removed from the plant as soon as possible since they might spread the illness. 
  • To stop the illness from spreading when you’re finished, clean your scissors or pruning instrument with rubbing alcohol. 
  • Enhancing air circulation around the plant is also crucial. 
  • Moving it to a more well-lit area or improving the airflow in the space can do this.
  • Additionally, be careful not to overwater your plant, since doing so might encourage the development of the illness. 
  • It’s crucial to water your plant from the bottom up to avoid wetting the leaves. 
  • You might need to apply a natural fungicide, such as neem oil if the issue continues. 
  • Selecting a plant that is resistant to Anthracnose is crucial for preventing the disease from ever developing in the first place. 
  • Look for a Hoya plant with healthy leaves and no symptoms of illness when purchasing one. As overcrowding can restrict air circulation and make it more difficult for the plant to get rid of illness, you should avoid doing it to your plants.

e) Infection with bacteria

Black spots on Hoya leaves might also be caused by bacterial infections. Bacterial leaf spot and bacterial blight are two of the most prevalent bacterial diseases that will damage your Hoya plants!

1. Leaf Bacterial spot

Hoya plant leaves can become infected with bacterial leaf spots.  A bacterium known as Xanthomonas campestris pv. Vitians, that attack stems, and leaves through open wounds, are responsible for the illness.

After becoming infected, leaves first exhibit tiny patches that soon enlarge and turn brown or black. The entire leaf may turn brown and wither away in extreme circumstances. 

The illness may live for a long time in plants and is transferred by water, wind, and tools. It is crucial to maintain proper cleanliness in the garden, such as using clean equipment and promptly discarding sick plant debris, to stop the spread of bacterial leaf spots.


It is crucial to respond right away if you suspect your plant has a bacterial leaf spot. 

  • The first step is to cut off any plant leaves that are harmed. 
  • To stop the illness from spreading, you should also clean your scissors or pruning tools with rubbing alcohol. 
  • Additionally, make sure you are not overwatering the plant and improve air circulation around it. 
  • You might need to use a copper-based fungicide or bactericide if the issue doesn’t go away.
2. Bacterial Blight

One more disease that can harm your beautiful Hoya plants and result in black patches on their leaves is bacterial blight. A bacteria known as Pseudomonas syringae pv. Syringae, which attacks plant leaves and stems through open wounds, is the culprit behind the illness. 

Small water-soaked patches that swiftly become dark or black appear on the leaves after infection. The spots frequently have a yellow halo around them, and eventually, the leaves may fall off the plant. Sterilize your gardening instruments before each use to prevent bacterial blight, and avoid hurting plants.


  • The best course of action if you suspect your Hoya has bacterial blight is to remove and discard any infected leaves. 
  • To stop the illness from spreading, sanitize your gardening equipment and steer clear of injuring the plant. 
  • To help manage the germs, you may also try applying a fungicide with a copper base. Because too much copper can be hazardous to plants, always carefully follow the directions on the package. 
  • One tablespoon of baking soda mixed with one quart of water can also be used to treat the plant. 
  • Use a delicate cloth to apply the solution using once per week to the impacted leaves.

3. Viral Infection that can affect your hoya plants

A viral infection is yet another likely explanation for why Hoya leaves have black dots. Hoya plants are susceptible to a wide range of viruses, including the impatiens necrotic spot virus, cucumber mosaic virus, and tobacco mosaic virus.  These viruses are carried by insects like aphids and whites, and they can also spread through infected gardening equipment.   

Black stains on the leaves, slowed growth, yellowing leaves, and abnormalities are signs of viral infection. It’s crucial to maintain proper cleanliness in the garden and abstain from handling plants if you’re contagious to stop the transmission of infections.

Additionally, you should constantly check your plants for pest indicators and get rid of them right away.

How To Treat A Viral Infection

Sadly, there is no treatment for viral infections. 

  • To stop the virus from spreading, the best course of action is to remove the afflicted plant from your garden. 
  • To stop the disease from spreading, you should also clean your gardening equipment with bleach or rubbing alcohol.

4. Pests

Pests are a last potential explanation for the black patches on Hoya leaves. Common pests that can infest Hoya plants and leave them with black spots on their leaves are mealybugs, scale insects, and aphids. These bugs feed on the sap of the leaves, causing them to yellow, grow slowly, and finally develop black patches.

1. Aphids

Small, oblong-shaped aphids come in a variety of colors, including black, brown, green, and white. They may multiply swiftly and are frequently found in groups on plant stems and leaves. Aphids produce a sticky liquid called honeydew that attracts other pests and encourages the growth of sooty moulds on plants.

2. Scale Bugs

Scale insects are little, brittle bugs with brown, black, or white bodies. They frequently inhabit the stems and leaves of plants, sucking the sap. 

Additionally, honeydew produced by scale insects can draw in additional pests and promote the growth of sooty mould on plants.

4. Mealy Bugs

Small, oval-shaped mealybugs have a white, waxy coating all over them. They consume plant sap, which can result in leaf loss, withering, and stunted development in plants. Additionally, honeydew produced by mealybugs can draw in additional pests and encourage the development of sooty mould on plants.

How To Treat Pests

  • The most effective option if you believe your Hoya plant has bugs is to manually remove them. 
  • Wipe the bugs off the plant carefully with a soft cloth. 
  • You might also try forcing them away from the plant with a strong stream of water.
  • You can apply a natural pesticide, like neem oil, if the infestation is severe. Because too much pesticide might harm plants, always carefully follow the directions on the package. 
  • Try combining 1 tablespoon of dish soap with 1 quart of water to create a DIY pesticide. 
  • Spray the remedy on the afflicted plant, being careful to get it all the way down to the leaf undersides. 
  • Up till the pests are eliminated, repeat this treatment every several days.

5. Beware of shore flies – tiny files

It is a small insect that lays its eggs in the soil of hoya plants. A shore fly larva looks like a worm with a clear body. These pests leave black spots on hoyas and other indoor plants due to their waste.

They don’t directly affect plants, but they can spread disease when people touch infected unhygienic leaves.


Gently wipe the leaves that contain black spots with a damp, soft cloth. As flies tend to carry diseases, clean your hands afterwards.

Also, a lot of algae attracts shore flies, as algae are their primary food source. So, if a hoya plant isn’t covered in algae, it won’t attract shore flies. Moreover, by watering your hoya only when necessary, you can effectively reduce the growth of algae, so shore flies won’t return to your plant.

How To Prevent Black Spots on Hoya Leaves

By practising good gardening hygiene and caring for the hoya properly, you can prevent black spots on the hoya leaves. So, here are some tips for preventing black spots on hoya leaves:

  1. Clean your gardening tools before using them on your hoya plant. By doing this, you will prevent diseases or pests from spreading.
  2. Don’t water your hoya overhead. Spots can occur from splashed water spreading diseases and promoting fungal growth on leaves.
  3. Maintain a clean and debris-free environment around your hoya plant. It will help to prevent the spread of diseases and pests.
  4. Plant hoya in well-draining soil, place it in bright indirect light and water it when the soil is dry to the touch.
  5. Keep your hoya plant well-ventilated. An effective air circulation system prevents fungal growth and the spread of diseases.
  6. Keep an eye out for signs of pests or diseases on your hoya plant. Remove any black spots from the leaves as soon as you see them.

By following the above tips, you are sure to prevent hoya plant black spots.


Q1. Can my Hoya plant be easily burned? 

Ans. As indoor plants, Hoyas don’t need a lot of sunshine to survive. A minor sunburn can occasionally happen when you receive too much sunshine. Typically, the result of this sunburn is the development of red dots on the leaves.

Q2. What do the white dots on the Hoya plant mean? 

Ans. Mineral buildup on the leaves can be the cause. A mealybug or white scale infestation is another possibility.

Q3. What do the yellow spots on the Hoya plant mean? 

Ans. A shortage of nitrogen is the cause of this issue.

Q4. What do the brown markings on the Hoya plant mean? 

Ans. This might be due to the Hoya plant being overwatered or underwatered.


Hoya plant leaves can develop black spots for a variety of reasons which I have discussed above. You may help avoid black spots on Hoya leaves by taking a few easy precautions and being careful about checking your plant. 

Take urgent action to treat the plant and remove the reason if you discover black spots on the leaves of your Hoya plant if you want to save your plant. Your Hoya plant will soon be vibrant once more if you give it the right care and attention.

Are you a hoya-obsessed lover like me too? Never enough I say!

I hope my article is informative to you and if you like my article, please comment down below, and don’t forget to share this article with your friends and family!

Happy gardening to you!

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  • Manish Lakhera

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