Hydrangeas are beautiful flowering shrubs that add vibrant pops of color to gardens. Their large showy blooms come in shades of pink blue, purple, white and green. However, hydrangea flowers are delicate and prone to certain issues, like the development of ugly brown spots. If you’ve noticed brown splotches marring the beauty of your hydrangea blooms, this common problem likely has several potential causes. Read on to learn why brown spots appear on hydrangea flowers and what you can do to fix it.
What Causes Brown Spots on Hydrangea Flowers?
There are a few key reasons brown spots may start showing up on your hydrangea’s gorgeous blooms:
Sunscalding
Too much hot sun can literally burn hydrangea flowers, especially white ones. If flowers are exposed to intense sunlight during peak heat hours, from around 11am to 3pm, the delicate petals can become sunscalded. This causes ugly brown burnt spots to develop. Any hydrangea placed in full sun is at risk of getting sunscalded flowers.
Water Issues
Improper watering often contributes to brown spots. Overwatering encourages fungal diseases that can damage flowers. And underwatering leads to drought stress, which causes spotting and crispy brown edges on petals. Getting the right amount of water to hydrangeas can be tricky.
Pests
Insects that feed on flowers can cause brown spots on hydrangeas. Aphids spider mites and thrips are common culprits. They extract fluids from petals leaving behind brown splotches and distorted, withered flowers.
Fungal Diseases
Certain fungi target hydrangea blooms. Botrytis blight, also called gray mold, is one of the most prevalent. It manifests as brown spots with fuzzy gray centers on flowers and also blights leaves. Other fungal culprits are rust, leaf spot and powdery mildew. Wet conditions encourage these diseases.
Chemical Damage
Using certain garden chemicals improperly around hydrangeas can inadvertently damage delicate flowers. Herbicides, pesticides and fertilizers may burn petals if overapplied and allowed to drift onto blooms. This leads to brown spotting.
Hard Water
Using hard water that contains minerals and chemicals to water or spray hydrangeas can also cause brown spotting on flowers. The compounds in the water negatively interact with the blooms.
Age
As flowers naturally age and start to fade, they turn brown Older blossoms on a hydrangea will show spotting before younger ones Deadheading spent blooms helps prolong the life of hydrangea flowers.
How to Fix Brown Spots on Hydrangea Flowers
Once you’ve diagnosed what’s causing the brown spots on your hydrangea’s flowers, you can take these steps to fix the problem:
Adjust Sun Exposure
If sunscalding is causing spotting on flowers exposed to too much direct sun, first relocate susceptible hydrangea varieties like bigleaf, panicle and smooth hydrangeas to a partly shaded spot. East facing locations are ideal. Or plant them near taller plants, structures or fences that provide afternoon shade.
Improve Watering
Make sure hydrangeas get about 1 inch of water per week, and avoid overwatering, which encourages fungal disease. Water at the base, not the leaves. Add mulch around plants to retain moisture. Consider installing a drip irrigation system for convenience.
Control Pests
Inspect flowers for signs of pests like aphids, spider mites and thrips. Remove them manually or use organic insecticidal soap. Encourage natural predators like ladybugs and lacewings. Sticky traps also help control pests.
Treat Fungal Diseases
Apply fungicides containing chlorothalonil, myclobutanil or propiconazole at the first sign of fungal problems like botrytis. Improve air circulation and avoid overhead watering. Remove and destroy infected plant parts.
Stop Using Harmful Chemicals
Switch to organic gardening methods. Apply any chemicals carefully to avoid drift onto hydrangea flowers. Consider natural fungicides and insecticides instead of synthetic versions.
Use Rainwater
Collect rainwater in barrels to use for watering and spraying hydrangeas. Or consider installing a reverse osmosis filtration system to remove minerals if you must use hard tap water. This will help prevent chemical damage to flowers.
Deadhead Regularly
Snip off spent hydrangea blooms as they start to decline. This encourages new flower growth. Deadheading also stops dying blooms from developing unsightly spots as they age.
Prune Damaged Growth
If despite your best efforts, significant portions of hydrangea flowers turn brown, simply prune away the damaged parts. Cut back to just above healthy growth buds. This nudges the plant to generate fresh new blooms.
With some troubleshooting and adjustments to care, you can get your hydrangea’s gorgeous blossoms looking spot-free again. Pay attention to proper sunlight, hydration, pest control and disease prevention when cultivating these flowering shrubs. Your efforts will be rewarded with beautiful, long-lasting colorful blooms.
How to make compost tea
Compost tea is an easy-to-make natural remedy for brown spots on hydrangea leaves, says Jason White, the CEO of All About Gardening. To do so, he recommends using an old pillowcase or a burlap bag and filling it with compost.
This will act as your tea bag as you place it in five gallons of water and leave it to steep for three days, he says. After this time, Jason suggests pouring the liquid into a spray bottle [such as this one on Amazon] and applying it to the brown leaf spots of your hydrangeas.
Expert Jen Stark similarly encourages gardeners to try this compost tea remedy. Adding compost tea to a spray bottle and spritzing it on the brown spots on your plants can help remove them, she adds. ( credit: Future)
How does compost tea treat brown spots on hydrangeas?
How does this organic treatment fight this common problem? Jason explains that the compost tea has beneficial bacteria that will effectively fight the bacteria responsible for brown leaf spots in the hydrangeas.
And, to protect your plant further, he suggests spraying the plant with diluted liquid kelp to boost its immune system so as to prevent the spots from recurring. ( credit: Proven Winners)
Q&A – Why does my hydrangea have brown dark spots all over?
FAQ
How do you get rid of brown spots on hydrangeas?
The problem is caused by a fungus that spreads via spores in wet or humid conditions. To control leaf spot, avoid watering your hydrangeas from overhead, and again, remove and destroy diseased plant parts. If summer rains make the problem worse, try a fungicide such as Immunox (always follow label directions).
What to do when my hydrangea flowers turn brown?
Are the blooms on your hydrangea shrubs fading or turning brown? No need to worry – this is simply a sign that it’s time to remove the flowers, a process called deadheading. When you deadhead hydrangeas, you aren’t harming the plants at all.
How do you treat brown spots on plants?
If you see brown or yellow spots that are sunken and growing in size over time, this could be something called anthracnose, a type of fungus. It’s not usually harmful, just unsightly. Solution: Isolate your plant and cut off affected leaves. You’ll probably need to use a fungicide to eliminate the problem.
What does overwatered hydrangea look like?
What do overwatered hydrangeas look like? Hydrangeas that have been overwatered will likely have fewer blooms and wilting leaves and flowers. The leaves may also turn yellow and feel soft and squishy.