Yellowing hydrangea leaves can ruin the balanced look of these lush, leafy shrubs. Healthy hydrangea leaves range from medium to dark green, offering a striking contrast to their vibrant blooms.
Different patterns and degrees of yellowing provide clues to help identify and fix the problem. If your plant’s leaves are losing their luster, consider these seven potential causes of yellowing hydrangea leaves—and how to restore your plant’s health and beauty.
1. Improper Watering
Water-related issues are the best place to start. These problems are usually easy to identify and fix—especially if you act before root rot sets in. A moisture meter can help you determine the right solution.
Overwatering
Hydrangeas often droop in the heat of the afternoon. But if the leaves haven’t perked back up by evening—or are still wilted in the morning—you may be overwatering. Wilted leaves turn yellow, then brown and mushy before falling off. Other symptoms include stunted growth, fewer and smaller blooms, and signs of root rot.
Stick your finger about 4 inches into the soil or use a moisture meter to check the soil. If it’s too wet, your hydrangea may be overwatered. Letting the soil dry out may help, but if yellowing continues, you’ll need to take further steps:
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Remove the plant from the ground and trim away any roots that aren’t firm and white.
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Replant in a better-draining area, or mix sand into the soil to improve drainage.
Underwatering
Too little water can also cause yellow leaves, often with brown, crispy edges. Don’t overcorrect with excess watering—that can make things worse.
Instead, water deeply until the soil is evenly moist. You may need to increase watering frequency. In general, watering deeply two to three times per week is enough. Adding mulch helps the soil retain moisture.
2. Poor Drainage
Hydrangeas prefer loamy or sandy soil over heavy clay, which can lead to overwatering problems.
Choose a planting site with good drainage—avoid low spots where rainwater collects. To test drainage, dig a 6–8 inch hole and fill it with water, then see how quickly it drains. You can improve drainage by mixing aged compost or sand into the soil around your hydrangeas.
3. Improper Sunlight
While some hydrangea varieties can tolerate more sun, most prefer morning sun and afternoon shade. Choose the right location, or move your plant if it’s getting too much direct sunlight.
Leaf Scorch
Too much intense sun, especially during the hottest part of the day, can cause leaves to yellow, brown, and become brittle.
Too Little Light
On the flip side, not enough sunlight slows photosynthesis and chlorophyll production, leading to pale, yellow leaves.
4. Poor Soil Quality
Poor soil can cause a range of problems, including improper watering, lack of nutrients, and disease—all of which contribute to yellowing leaves.
You can test the pH at home to see if it’s in the right range. For more detailed results, send a soil sample to your local cooperative extension office—they can identify nutrient deficiencies and overall soil quality.
Wrong Soil pH
Hydrangeas prefer slightly acidic soil with a pH between 5.0 and 6.5.
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Add lime to raise pH
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Add aluminum sulfate to lower pH
5. Nutrient Deficiency
Nitrogen Deficiency
Often occurs in spring. Leaves turn yellow and drop early. Since hydrangeas use a lot of nitrogen, the soil may become depleted quickly. Add compost and use a balanced, acid-loving plant fertilizer in spring to help.
Iron Deficiency
If new leaves are yellow but the veins remain green, your plant may lack iron. This is often caused by overwatering, poor drainage, incorrect fertilization, or overly alkaline soil.
Apply chelated iron for a quick fix. Long-term, you’ll need to amend the soil:
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Test and adjust pH to make it more acidic
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Use an iron-rich fertilizer formulated for acid-loving plants
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Compost with oak leaves, pine needles, and coffee grounds to improve soil acidity
Magnesium Deficiency
This is less common and usually shows in older leaves, which yellow while the veins stay green. Hydrangeas naturally grow in magnesium-poor soil, making it tricky to correct.
Epsom salts or dolomitic lime can add magnesium, but be cautious—lime also raises pH. Try foliar sprays with liquid seaweed extract. Avoid fertilizers high in potassium, which can interfere with magnesium absorption.
6. Improper Fertilization
Too much, too little, or the wrong kind of fertilizer can damage plants and turn leaves yellow. Use products designed for acid-loving plants like hydrangeas or azaleas, and always follow label directions.
7. Disease and Pests
Diseases
Hydrangeas are vulnerable to fungal, bacterial, and viral infections. Hydrangea mosaic virus and tomato ringspot virus both cause yellowing leaves.
Practice good garden hygiene to prevent mosaic virus—always prune with sterile tools and disinfect between cuts. Tomato ringspot is spread by nematodes, so plant resistant varieties when possible.
Pests
Insects can damage leaves and spread disease. Spider mites, for example, cause speckled yellowing, then holes, then leaf drop. Look for tiny webs and damage on the leaf undersides. Treat with neem oil or horticultural oil.
FAQs
What does an overwatered hydrangea look like?
- Leaves may turn yellow or have yellow areas with green veins. They may look limp and wilted. The plant may bloom less, and flowers may droop or die. New growth might be stunted.
How do I fix yellow hydrangea leaves?
- If wet soil is the issue, let it dry before watering again. Adjust the soil pH to the ideal range. Spray leaves with seaweed extract or apply a diluted Epsom salt solution to the soil around your hydrangea.