The Hibiscus bush is a well-known tropical plant with gorgeous trumpet-like flowers. With over 200 species of Hibiscus, the flowers have a range of sizes and colors.
Hibiscus plant care will vary depending on the species and variety and whether it’s grown outdoors or indoors. However, there are some basic principles for caring for all varieties of Hibiscus plants.
Your Hibiscus bush will do best in full or partial sun with well-draining soil. While the Hibiscus plant tolerates alkaline soils, it thrives in neutral to slightly acidic soil.
In addition, the Hibiscus plant appreciates the application of balanced fertilizer in the spring and moderate watering.
So, if you’re taking care of your plant and providing it with proper care, why are there spots on the Hibiscus leaves?
The short answer- the cause could be bacteria, fungi, or a garden pest. Extreme temperature changes, improper watering, and a lack of fertilization can be at fault.
Common Problems With Hibiscus Plant Leaves
While yellowing Hibiscus leaves can occasionally be a common sight, it is typically a temporary situation.
However, if you have yellow leaves that persist on your Hibiscus bush, it’s time to figure out the cause.
Common causes of yellow leaves are:
- Overwatering or underwatering
- Too much sun or inadequate sunlight
- Extreme temperatures
- Lack of fertilization
Sometimes it isn’t easy to know if you’ve overwatered your plant until you notice the yellow leaves.
The best tip for adequately watering your plant is to keep the soil around the Hibiscus bush moist but not soggy. This tip should prevent underwatering and overwatering.
The Hibiscus plant is pretty tough but doesn’t enjoy extremes, including sunlight and temperature. The Hibiscus bush doesn’t appreciate full direct sun all day, nor can it handle full shade.
These things, including a lack of nutrients and fertilization, can cause your Hibiscus plant to have yellow leaves.
Black Spots On Leaves
Fungal Leaf Spots
Thankfully the black spots do not harm the plant, although they may be unattractive.
Unfortunately, there’s no treatment for making the black spots disappear, so the only option is to remove the infested leaves.
In addition, make sure to clean up any dropped leaves to prevent the disease from spreading.
The cause of fungal leaf spots is a cool, damp environment. It isn’t easy to prevent black spots if you live in this environment, but it’s another reminder not to overwater your plant.
Overwatering your plant at any time of the year, particularly in cool weather, can cause fungal leaf spots.
Bacterial Leaf Spot
If you notice black spots or rings of different colors on the edges of your Hibiscus leaves, you may be dealing with Pseudomonas cichorii.
This bacteria is common in wet and rainy climates and spreads by splashing water.
Unfortunately, if you live in this climate, there isn’t much you can do to prevent bacterial leaf spots, but overwatering your Hibiscus plant can also cause Pseudomonas cichorii.
Similar to fungal leaf spots, Pseudomonas cichorii doesn’t cause severe damage. However, the affected leaves will drop if there is a severe disease.
Once you notice the bacteria, removing any fallen leaves and pruning affected branches is a good idea.
If you notice brown or black spots on the underside of your Hibiscus plant’s leaves, scale is likely to blame.
Scales are insects with armored shell that sucks the plant’s juices, potentially causing severe damage.
The insects are unique because they don’t move their entire adult life, but their babies move quickly after hatching to find a new leaf or plant.
Unfortunately, their armored shell protects them from insecticidal sprays, but you can apply systemic insecticides in cases of severe infestation.
You can remove a small infestation with a q-tip or your fingernail.
Other Leaf Issues
If you notice orange or yellow bumps on your Hibiscus plant’s leaves, you may be experiencing Hollyhock rust aka Hibiscus rust.
Hollyhock rust is a fungal disease caused by the foliage’s prolonged exposure to moisture.
While Rust can be caused by a rainy and tropical environment, it is more likely to occur from watering your plant improperly.
For example, it is best with Hibiscus plants to water from the bottom, avoiding spraying the leaves. This method should reduce the chances of your Hibiscus Bush getting Hollyhock Rust.
Unlike some other causes of black spots, Hollyhock rust can kill the foliage and the plant, so it’s essential to water your plant from below.
If you notice gray spots on your Hibiscus leaves, it might be Botrytis Blight. This fungal disease is caused by reduced airflow and high humidity.
You may notice that your plant’s flowers are discolored and that flower buds fall off before blooming. If this happens, remove all infected flowers and leaves.
The best way to treat Blight is to keep the foliage dry. To do this, water from below and make sure not to overwater the plant.
Like Blight, Powdery Mildew looks like a white coating on the plant’s leaves. This fungal infection is prone to Hibiscus plants when the days are warm and nights are cool.
Thankfully, this mildew doesn’t harm the leaves, but it isn’t a beautiful sight.
Like the other fungal diseases, watering from below and avoiding the leaves can reduce the chances of powdery mildew.
Why Are There Spots on the Leaves on my Hibiscus Bush?
Whether your Hibiscus plant has yellow leaves, black spots, orange bumps, or a white coating, there’s a chance you can prevent it from happening again.
Changing your watering style can reduce the chances of these fungal and bacterial diseases and pests.
For example, if you have previously watered with a garden hose and sprayed the leaves, the watering style may have caused excess moisture, leading to your plant’s disease.
Watering your Hibiscus plant from below is the best option, so the foliage remains dry.
In addition, ensure that the Hibiscus plant needs to be watered, as excess moisture is the other culprit for most of these issues.