Hydrangeas are generally known for being pretty tough customers in the garden, and they don’t usually get hit by fungal issues too often. But every now and then, things go sideways. If your hydrangeas start looking a little funky, it’s usually easy to spot the problem if you know what to look for. Here’s a quick guide on the warning signs of hydrangea fungus and how to get your plants back to looking their best.
Common fungal issues include:
- Powdery & Downy Mildew
- Gray Mold (Botrytis)
- Leaf Spot
Spotting and Treating Mildew
When the weather gets warm and humid, fungus loves to move in. Hydrangeas are particularly susceptible to two types: Powdery Mildew and Downy Mildew. With Powdery Mildew, you’ll see a white, flour-like coating on the tops of the leaves. Over time, the leaf tissue dies off, and the leaves wither and drop.
Downy Mildew is a bit sneakier—it coats the *underside* of the leaves with a grayish-white fuzz. Eventually, you’ll see dark or yellow spots appearing on the top side. Keep a close eye on your foliage; any weird discoloration is usually a red flag that your plant needs help.
How to handle it:
- Prune off the affected parts and toss them in a sealed trash bag (don’t compost them!).
- For Powdery Mildew, try a spray rich in silica.
- For Downy Mildew, a homemade garlic tea/brew can work wonders as a natural remedy.
Dealing with Gray Mold (Botrytis)
Gray Mold is pretty unmistakable. It covers both leaves and flowers in a thick, dark gray fuzzy layer—much denser than mildew. If left alone, it can cause the stems to shrivel up and die. To save your hydrangea, you’ll want to act fast.
How to fight Gray Mold:
- Be aggressive with the shears! Prune away any infected stems and dispose of them in a sealed trash bin.
- Thin out the plant to improve airflow so moisture doesn’t get trapped.
- Water your hydrangeas in the morning. Always aim for the base of the plant; try to keep the leaves as dry as possible.
Managing Leaf Spot
Leaf Spot usually shows up when a plant is stressed from a lack of nutrients or if the air is just too humid for too long. You’ll notice brown spots forming on the leaves that get darker toward the center. Eventually, the tissue in those spots dies out completely.
How to treat Leaf Spot:
- Cut off the spotted leaves and get them into a sealed trash bag immediately.
- Give your hydrangeas some fertilizer to make sure they have the nutrients they need to stay strong.
- If the infestation is really taking over, you might need to use a fungicide to get things under control.
