January 18


Expert advice on preventing and managing eight common diseases that affect hydrangeas: the key to keeping your plants healthy

'Prevention is key' – expert tips for dealing with 8 common hydrangea diseases

When it comes to growing hydrangeas, prevention is key. By taking direct action and staying vigilant, gardeners can minimize the risks of their beloved plants falling prey to diseases. In this article, we will explore the most common hydrangea diseases and provide expert tips on how to prevent and treat them.

Aphids, powdery mildew, and black spot are some of the most common problems that can affect hydrangeas. These diseases can cause distorted foliage, black spots, and powdery white growth on the leaves. If left unchecked, they can significantly impact the overall health and appearance of the shrubs.

One of the best ways to prevent these diseases is to maintain good garden practices. This includes regular cleaning, removing fallen leaves and disposing of them properly, and providing proper growing conditions for the shrubs. Additionally, the use of natural fungicides, such as neem oil, can help treat and prevent these diseases.

Early detection is crucial when it comes to hydrangea diseases. Keep a close eye on your plants and inspect them regularly for any signs of infections. If you spot any unusual symptoms, such as yellowing leaves, distorted growth, or fungal spots, take immediate action to address the issue. The earlier you start treating a disease, the better the chances of saving your hydrangeas.

Gardeners have a variety of options when it comes to treating hydrangea diseases. From using homemade remedies to purchasing commercial products, there are plenty of ideas to explore. Published expert tips and advice, along with online resources and gardening forums, can provide more insights into the best ways to handle specific diseases.

In conclusion, prevention is key when it comes to dealing with common hydrangea diseases. By taking proactive measures and staying vigilant, gardeners can ensure that their hydrangeas thrive and grow in optimal conditions. With the right knowledge and tools, these beautiful flowering shrubs can bring joy and inspiration to any yard or garden.

How to spot hydrangea diseases

How to spot hydrangea diseases

Prevention is key when it comes to dealing with hydrangea diseases. Regularly inspecting your plants for signs of disease is crucial for early detection and effective treatment. Here are some tips for spotting hydrangea diseases:

  • Powdery Mildew: This fungal disease causes a powdery white coating on the leaves and stems of hydrangeas. It thrives in conditions with high humidity and poor air circulation. Look for small, distorted foliage and prevent the disease by providing good airflow and avoiding overhead watering.
  • Leaf Spot: Leaf spot is a fungal disease that causes circular brown spots on the leaves of hydrangeas. These spots can vary in size and may have a yellow halo around them. To prevent leaf spot, avoid overhead watering and remove and dispose of any diseased leaves.
  • Root Rot: Root rot is a common problem in hydrangeas and is usually caused by overwatering or poor drainage. Signs of root rot include wilting, yellowing leaves, and stunted growth. If you suspect root rot, check the roots for rotting or mushy sections. Improve drainage and avoid overwatering to prevent this disease.
  • Bacterial Wilt: Bacterial wilt is a serious disease that can cause sudden wilting and death of hydrangeas. It is spread by insects like aphids and can cause black or brown discoloration in the stems. Unfortunately, there is no cure for bacterial wilt, and infected plants should be removed and disposed of to prevent further spread of the disease.
  • Rust: Rust is a fungal disease that causes orange or brown spots on the leaves of hydrangeas. These spots may also have yellow halos. To control rust, remove and dispose of any infected leaves and use fungicidal sprays if necessary. Avoid overhead watering and provide good airflow to prevent rust.
  • Botrytis Blight: This fungal disease can cause a gray mold to develop on the flowers and buds of hydrangeas. Affected flowers may turn brown and become mushy. To prevent botrytis blight, avoid overhead watering and remove and dispose of any diseased flowers. Fungicidal sprays may be necessary for control.

By regularly inspecting your hydrangeas for signs of disease and taking preventative measures, you can help keep your plants healthy and vibrant. Remember to provide good airflow, avoid overhead watering, and remove any diseased foliage or flowers. If necessary, fungicidal sprays or other treatments can be used to control specific diseases. Prevention is always the best approach to dealing with hydrangea diseases!

1 Powdery mildew

Powdery mildew is a common fungal disease that affects hydrangeas. It is characterized by a white powdery coating on the leaves, stems, and flowers of the plant. If not treated, powdery mildew can weaken the plant and cause it to become stunted in growth.

To prevent powdery mildew, it is important to provide regular care and maintenance to your hydrangeas. Here are some tips:

  • If you want to add hydrangeas to your yard, choose a location with good air circulation and avoid planting them in areas with excessive shade.
  • Cleaning up fallen leaves and debris around the base of the plants can help prevent the spread of fungal spores.
  • When pruning hydrangeas, remove any infected or dead parts of the plant. This will help prevent the disease from spreading to healthy areas.
  • It is also recommended to prune hydrangeas only in the late winter or early spring, as pruning during the growing season can leave the plant susceptible to infections.
  • Using fungicides can be an effective control measure against powdery mildew. Some fungicides that are commonly used for hydrangeas include neem oil, sulfur, and potassium bicarbonate.
  • If you prefer organic options, there are also homemade sprays that can be effective against powdery mildew. These include baking soda sprays, milk sprays, and garlic sprays.
  • Infected plant materials should be disposed of properly to prevent the disease from spreading. It is important to bag up and throw away infected leaves, stems, and flowers instead of composting them.

By following these preventive measures, you can reduce the risk of powdery mildew and maintain the overall health and beauty of your hydrangeas.

2 Rust

Rust is a fungal disease that affects hydrangeas and is characterized by small, orange-brown spots on the leaves. These spots can eventually turn black and cause the affected leaves to become distorted and fall off. In severe cases, the disease can also affect the stems and flowers of the hydrangea.

Rust thrives in damp and humid conditions, making it more common in areas with high rainfall or in shady parts of the yard. It can also spread from plant-to-plant through direct contact or through wind-blown spores.

To prevent rust, it is important to provide good air circulation around your hydrangeas by planting them in a location with plenty of space and sunlight. Avoid overcrowding and prune your shrubs regularly to remove any diseased parts.

If you notice rust spots on your hydrangeas, it is important to act quickly to prevent the spread of the disease. Remove and destroy any infected leaves or flowers to reduce the risks of spreading spores. Lorraine Ballato, author of the book “Success with Hydrangeas,” recommends using a fungicidal spray like neem oil to control rust. Regular treatments with fungicidal sprays can help prevent the disease from recurring.

Overall, rust is not a fatal disease for hydrangeas, but it can cause aesthetic issues and impact the overall health and vigor of the plants. By following these tips and practicing good gardening practices, you can prevent and control rust on your hydrangeas.

3 Botrytis

Botrytis, also known as gray mold, is another common disease that affects hydrangeas. It is caused by the fungal pathogen Botrytis cinerea and thrives in cool, damp conditions.

Botrytis affects both the flowers and foliage of hydrangeas, causing brown spots and a fuzzy, grayish mold to develop. If left untreated, the disease can spread and cause significant damage to the plant.

To control Botrytis, it is important to take preventive measures. Here are some ideas to prevent and treat Botrytis on your hydrangeas:

  1. Remove diseased plant parts: When you spot any signs of Botrytis, such as brown spots or mold, make sure to remove the affected parts promptly. Dispose of the infected plant material properly to prevent the spread of the disease.
  2. Clean fallen leaves and debris: Regularly clean up fallen leaves and debris around your hydrangeas. These can harbor the fungal spores and contribute to the spread of the disease.
  3. Provide good air circulation: Botrytis thrives in humid environments, so it’s important to ensure good airflow around your hydrangeas. Prune the shrubs to create an open and airy shape, and avoid planting them too close together.
  4. Avoid overhead watering: Watering your hydrangeas directly on the leaves can create the perfect conditions for Botrytis to develop. Instead, water at the base of the plants and avoid wetting the foliage.
  5. Apply fungicides: In severe cases or when preventive measures are not sufficient, you can consider using fungicides labeled for botrytis control. Follow the instructions carefully and apply the sprays as directed.

Prevention is key when it comes to dealing with Botrytis on hydrangeas. By following these tips and maintaining good plant hygiene, you can reduce the chances of your hydrangeas getting infected and ensure their overall health and beauty.

Disclaimer: The information provided in this article is for educational purposes only and does not constitute medical or gardening advice. It is always recommended to consult with a professional before treating or diagnosing plant diseases.


  • Lorraine Ballato, “How to grow healthy hydrangeas”. Published on Amazon.
  • Lorraine Ballato, “Hydrangeas: A Gardener’s Guide”. Published by Timber Press.

4 Leaf Spot

One of the most common diseases that can affect hydrangeas is leaf spot. Leaf spot is caused by a fungal infection and can result in unsightly spots on the leaves of the plant.

Leaf spot typically appears as small, dark spots or rings on the leaves. These spots may grow larger over time and cause the leaves to become distorted or discolored. In severe cases, the leaves may even drop from the plant.

To prevent leaf spot, it is important to maintain good garden hygiene. This includes regularly cleaning up fallen leaves and avoiding overhead watering, as wet conditions can promote the growth of fungal infections.

If leaf spot does occur, there are several treatment options available. One recommended option is to prune away any infected leaves or branches and dispose of them in the trash. This can help to prevent the spread of the disease to other parts of the plant.

Another treatment option is to use fungicide sprays. These sprays can be applied to the foliage of the plant to control the fungal infection. Neem oil, which is a natural and organic fungicide, is often recommended for use on hydrangeas.

In addition to fungicides, there are other natural remedies that can be used to treat leaf spot. Some gardeners have had success using a mixture of water and dish soap to eliminate the fungal infection. Others recommend using a solution of baking soda and water.

In terms of prevention, it is also important to avoid planting hydrangeas in areas with poor air circulation, as this can increase the risk of fungal infections. Additionally, regular fertilization can help to keep the plants healthy and make them less susceptible to disease.

Overall, leaf spot is a common problem for hydrangeas, but with proper care and attention, it can be prevented and treated. By following these tips, gardeners can keep their hydrangeas looking healthy and beautiful.

5 Anthracnose

5 Anthracnose

Anthracnose is a common fungal disease that affects hydrangeas. It can cause dark brown to black spots on the leaves, stems, and flowers of the plant. Anthracnose is most common in areas with high humidity and warm temperatures, but it can affect hydrangeas in any region.

Anthracnose can spread easily from plant-to-plant, so it’s important for gardeners to be aware of the signs and take steps to prevent its spread. Lorraine Ballato, the author of “Success with Hydrangeas,” recommends cleaning up fallen leaves and other plant debris in the fall, as these can serve as a source of infection.

If you do notice anthracnose spots on your hydrangeas, it’s important to treat the affected plants promptly. Remove any diseased foliage or flowers, and dispose of them properly. Prune out any infected stems or branches, making sure to sanitize your pruning tools between cuts. Applying a fungicidal spray can also help to control the disease.

Prevention is key when it comes to anthracnose. Avoid overwatering your hydrangeas, as wet conditions can promote the growth of the fungal spores. Provide your plants with proper air circulation by spacing them out and pruning them regularly. Avoid working in the garden when the foliage is wet, as this can help to reduce the risk of spreading the disease.

In addition to anthracnose, hydrangeas can also be susceptible to other fungal diseases like powdery mildew and black spot, as well as bacterial infections like leaf spots and bacterial wilt. Aphids, scale insects, and other pests can also cause problems for hydrangeas. To reduce the risk of these diseases and pests, it’s important to keep your hydrangeas healthy and well-maintained.

Regularly inspect your hydrangeas for any signs of disease or pest infestation. If you notice any issues, take action early to prevent them from spreading. Prune out any damaged or diseased plant parts and dispose of them properly. Applying organic fungicides or insecticides, like neem oil, can also help to control these problems.

By following these tips and taking proactive measures, you can keep your hydrangeas looking their best and prevent the spread of common diseases. Remember that prevention is key when it comes to hydrangea health!

6 Bacterial wilt

Bacterial wilt is a serious disease that can affect hydrangea plants in the home garden. It is caused by the bacterium Pseudomonas solanacearum and can result in the wilting and death of infected plants.

One of the main symptoms of bacterial wilt is the sudden wilting and yellowing of the leaves, often accompanied by brown streaks or spots on the stems. The bacteria can enter the plant through wounds or natural openings and spread through the water-conducting tissues, causing wilting and eventual death.

There are no fungicides or sprays that can effectively treat bacterial wilt, so prevention is key in controlling the disease. To avoid bacterial wilt, it is important to follow good gardening practices, such as keeping the garden clean, removing any fallen leaves or debris, and pruning infected parts of the plant.

When pruning, be sure to clean your tools with a solution of 10% bleach or 70% rubbing alcohol to prevent the spread of bacteria from plant-to-plant. In addition, avoid planting hydrangeas in areas where bacterial wilt has been a problem in the past.

If your hydrangeas are already infected with bacterial wilt, there is not much that can be done to treat the disease. The infected plants should be removed and destroyed to prevent the spread of the bacteria to other plants in your yard.

In terms of prevention, it’s also important to note that bacterial wilt thrives in warm, humid conditions, so providing adequate air circulation and avoiding over-watering can help reduce the risks of infection. Ensuring that your hydrangeas are planted in well-drained soil and receiving the right amount of sunlight can also help prevent the disease.

Overall, the best control for bacterial wilt is prevention. By following these tips and maintaining good gardening practices, you can reduce the risks of bacterial wilt and keep your hydrangeas healthy and thriving.

7 Mosaic Virus

Mosaic virus is a common problem that affects hydrangeas. It is caused by a viral infection and can have a serious impact on the overall health and appearance of your plants.

Symptoms: The symptoms of mosaic virus include mottled or distorted leaves, yellowing or whitening of leaf veins, and stunted growth. Infected plants may also produce fewer blooms than healthy plants.

Causes: Mosaic virus is mainly spread through sap-feeding insects such as aphids. It can also be transferred from plant to plant through contaminated gardening tools.

Prevention: To prevent mosaic virus, it is important to keep your hydrangeas healthy and strong. This includes providing them with proper care, such as regular watering and fertilizing, as well as removing fallen leaves and debris from around the plants.

Treatment: Unfortunately, there is no cure for mosaic virus. Infected plants should be removed and destroyed to prevent the spread of the virus to other nearby plants. It is also important to clean and disinfect any tools used on infected plants to avoid contamination.


  • Choose disease-resistant varieties when planting hydrangeas.
  • Monitor your plants regularly for signs of infection.
  • If you see any leaves with mosaic virus symptoms, remove them immediately.
  • Use insecticidal soap or neem oil to control aphids and other sap-feeding insects.
  • If you’re unsure whether your plant has mosaic virus, consult a professional gardener or horticulturist for diagnosis and advice.

8 Ringspot Virus

8 Ringspot Virus

Ringspot virus is a common viral disease that can affect hydrangeas and cause various symptoms. It is typically transmitted through plant-to-plant contact or by aphids, so it’s important to be aware of the risks and take preventive measures to avoid infections.

Symptoms: Hydrangeas infected with ringspot virus may develop circular or ring-shaped spots on the leaves. These spots can range in color from black to brown or yellow, and they may enlarge over time. The affected foliage may also become distorted or exhibit stunted growth.

Causes: Ringspot virus is caused by a type of RNA virus and can be spread through direct contact with infected plants or by aphids feeding on infected foliage. It can also be transmitted through pruning tools if they are not properly cleaned between uses.

Prevention: To prevent ringspot virus and other viral infections, it is important to start with healthy plants from a reputable source. Avoid planting hydrangeas in areas where the virus is known to be prevalent. Implement good gardening practices like cleaning your pruning tools regularly to avoid spreading the virus or other pathogens. Additionally, you can reduce the risks by avoiding direct contact with aphids, which are carriers of the virus.

Treatment: Unfortunately, there is no cure for ringspot virus in hydrangeas. If your plants are infected, it is recommended to remove and dispose of the diseased foliage to prevent further spread of the virus. Pruning infected parts of the plant may help in some cases, but overall, prevention is key.

Fungicidal options: While fungicides are not effective against viral diseases like ringspot virus, they can be helpful in preventing or treating fungal infections that may occur alongside the viral infection. If you notice fungal diseases like leaf spots or anthracnose, applying appropriate fungicidal sprays can help control these problems.

Inspiration: If you’re looking for inspiration on how to grow healthy hydrangeas and deal with common diseases, Lorraine recommends visiting websites or reading books on hydrangea care. You can find great tips and ideas from experienced gardeners and learn about the latest trends in hydrangea cultivation.

Recommended products: If you want to purchase products to help prevent or treat diseases in your hydrangeas, Lorraine suggests checking out online retailers like Amazon, where you can find a wide range of fungicides, neem sprays, and other options.


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