What Your Hydrangea Leaves Are Trying to Tell You

Hydrangeas are beautiful flowering shrubs, but their leaves can sometimes look like they are having a rough day. Brown spots may appear seemingly out of nowhere. Leaves may droop in the afternoon even though the soil feels moist. Some leaves may turn yellow and fall to the ground.

Before reaching for the watering hose or spraying every product in the garden shed, take a closer look. Your hydrangea may simply be reacting to normal summer heat. However, it could also be showing signs of a fungal disease, poor drainage or a nutrient problem.

How to Identify Spots on Hydrangea Leaves

Not every spot on a hydrangea leaf is caused by the same problem. One of the most common issues is Cercospora leaf spot. This fungal disease often begins on the lower leaves and gradually works its way upward through the plant.

Cercospora leaf spots are usually small, round and brown or purple. Many spots develop a lighter tan center with a darker outer edge. As the disease spreads, affected leaves may turn yellow and fall from the plant.

Another possible problem is anthracnose. These spots are often larger and may have dark rings that resemble a bull’s-eye or target. Anthracnose can affect the leaves and flowers.

If the leaves look like they have been lightly dusted with flour or baby powder, the problem may be powdery mildew. Powdery mildew may also cause the leaves to curl, pucker or develop purple discoloration.

Leaf spots are more likely to appear during humid weather, rainy periods or when the leaves remain wet for long periods of time.

Why Does My Hydrangea Look Wilted in the Sun?

A hydrangea can look thirsty even when the soil is properly watered. During the hottest and brightest part of the day, the leaves may droop or fold away from the sun. This is often a temporary reaction to heat stress.

Large hydrangea leaves can lose moisture faster than the roots can replace it during intense afternoon sunlight. Drooping helps the plant reduce its exposure to the sun until the temperature begins to cool.

Before adding more water, check the soil a few inches below the surface. If the soil is already moist, leave the plant alone and check it again after the sun moves away. If the leaves perk back up during the evening or by the next morning, the plant was most likely protecting itself from the heat.

Adding more water every time the leaves droop can cause a new problem. Waterlogged soil prevents the roots from getting enough oxygen and may eventually lead to yellow leaves, weak growth and root rot.

Bigleaf hydrangeas are especially likely to struggle in harsh afternoon sunlight. They usually grow best with morning sun and some afternoon shade. Adding a two- to three-inch layer of mulch can also help keep the soil cooler and reduce moisture loss.

Why Are My Hydrangea Leaves Turning Yellow?

A few older yellow leaves near the bottom of the plant are not always a reason to worry. Older leaves may naturally turn yellow and fall as the plant puts its energy into newer growth.

However, widespread yellowing may indicate a problem.

If the soil stays soggy for long periods, the roots may be struggling because of poor drainage or excessive watering. If newer leaves turn yellow while the veins remain green, the plant may be experiencing iron chlorosis. This often happens when the soil is too alkaline or when heavy clay soil makes it difficult for the plant to absorb nutrients.

Yellow leaves with brown or purple spots are more likely to be related to a fungal leaf spot disease.

Remove Fallen Leaves to Help Stop Fungus

If a hydrangea has fungal leaf spots, do not leave fallen leaves piled around the base of the plant. Fungal spores can survive in infected plant debris and may contribute to future problems.

Remove spotted leaves that have fallen to the ground and dispose of them. Do not add diseased leaves to a compost pile unless your compost becomes hot enough to kill pathogens.

Keep the area around the plant clean. Avoid watering over the top of the shrub whenever possible. A drip irrigation line, soaker hose or slow watering at the base of the plant is a better option.

Hydrangeas also benefit from good air circulation. Avoid planting shrubs too close together, and remove nearby weeds that may trap moisture around the plant.

Best Treatments for Hydrangea Leaf Spots

Fungicides are most helpful when they are applied early. They are generally better at protecting healthy leaves and new growth than repairing leaves that are already damaged. Once a leaf is covered with spots, it will not become spotless again.

Several homeowner products may help control fungal diseases on ornamental plants. Always read the product label carefully before spraying because the approved uses and application instructions can vary.

GardenTech Daconil Fungicide Concentrate and Bonide Fung-onil Multi-Purpose Fungicide contain chlorothalonil. Chlorothalonil is a broad-spectrum fungicide commonly used to help control leaf spots and other listed fungal diseases on flowers and shrubs.

Bonide Captain Jack’s Copper Fungicide is another option for certain fungal diseases, including some leaf spots and powdery mildew. It is available in several forms, including ready-to-use sprays and concentrates.

Southern Ag Liquid Copper Fungicide is another copper-based product labeled for many fungal and bacterial leaf spots on ornamental plants.

Bonide Infuse Systemic Disease Control contains propiconazole. It is labeled for several diseases affecting flowers, trees and shrubs, including certain leaf spots, powdery mildew and anthracnose.

Do not combine fungicides unless the product labels specifically allow it. Apply treatments during the cooler part of the day. Wear the protective equipment listed on the label, and keep children and pets away from the treated area until the spray has dried.

A Healthy Hydrangea Starts With Good Habits

The best defense against hydrangea leaf spots is not always a spray bottle. Good watering habits, clean garden beds, proper spacing and the right amount of sunlight can make a big difference.

Water near the base of the plant, remove diseased leaves, keep the foliage as dry as possible and avoid overwatering a hydrangea simply because it droops during the afternoon heat.

A hydrangea with a few spotted or yellow leaves is not necessarily dying. With careful observation and the right care, most hydrangeas can recover and continue blooming beautifully.