5 Common Hydrangea Diseases and Cures (Guide for 2021)

When everything is blooming the way it should, hydrangeas are among the most beautiful garden flowers out there. But while they might be beautiful when they bloom successfully, there are also a litany of diseases that can strike and ruin your beautiful flowers.

But knowing what’s out there, how to prevent it, and how to treat it if it does strike is the best way you can ensure you get a beautiful bloom year after year. That’s why we came up with this comprehensive guide to walk you through everything you need to know about the most common hydrangea diseases out there.


5 Common Hydrangea Diseases and Cures

While some sites pride themselves on throwing as many possible diseases out there at you, we wanted to take a simpler approach. We highlighted the five most common hydrangea diseases out there, and even lumped a few of them together.

common hydrangea disease

If you can identify the hydrangea diseases in the same way, and they have the exact same treatment options, then it really doesn’t matter what exact pathogen is ailing it!

Botrytis Blight

Botrytis blight is a fungal disease that’s relatively common in hydrangea plants. This fungal infection can come as a result of lingering water, and you’ll know your plants have it when you start to notice petals turning brown and falling off.

Moreover, you’ll notice plenty of leaf spots, and many flower buds will die before they have a chance to open. Botrytis blight is fairly common, but it can also be a frustrating one to get control over, depending on where you live.

How to Treat

Treating Botrytis blight means preventing the conditions where it can thrive, and applying a fungicide to kill off the blight and prevent it from coming back when it does show up.

You need to ensure that there is adequate space between each plant, remove crop debris, and do your best to maintain a lower humidity. You should also avoid watering your plants later in the day, because when you water during these times the water can sit for an extended period.

Standing water is an ideal medium for Botrytis blight to grow, so anything you can do to avoid standing water around your hydrangeas is also a good idea.

Cercospora Leaf Spot

Cercospora leaf spot is another fungal problem that can infect your hydrangea plants. They appear as tan spots, with a reddish-brown halo on the leaves. Over time these leaves will die, and this can kill the entire hydrangea plant.

How to Treat

If you’re struggling to tell the difference between Cercospora leaf spot and Botrytis blight, there’s good news. The treatments for Cercospora leaf spot and Botrytis blight are almost identical.

Both diseases thrive in high humidity areas, so keeping sitting water from sitting on the leaves is the best way to control the disease. When you’re trying to water the plants, do your best to keep water off the leaves, and also try to water them early in the day.

Remove dead leaves and other clutter as soon as possible, and apply a fungicide to kill off an active infection. Once the current infection is gone, you can also continue to apply a fungicide to prevent new infections from taking root.

Powdery Mildew

Powdery Mildew on hydrangea

Powdery mildew is far from a hydrangea-specific disease, but that doesn’t mean it’s not a serious fungal infection that can take over your entire garden in no time. Powdery mildew spreads via air spores, which means there’s almost no way to prevent it from finding its way into your garden.

Powdery mildew displays itself via yellow areas on the leaves. Over time these spots can turn purple in color. Additionally, powdery mildew presents itself as a powdery white fungal growth on the lower surfaces of the leaf.

How to Treat

Unfortunately, about the only thing you can do to treat powdery mildew is to apply a fungicide as early as possible. Keep in mind that since powdery mildew spreads via air particles, if you don’t treat powdery mildew as soon as possible it will quickly spread to just about every other plant in your garden.

The powdery mildew itself isn’t very harmful, but it can take over an entire plant and prevent it from completing photosynthesis by blocking all the leaves. When this happens, your hydrangeas will die.

Virescence

Virescence is one of the worst infections that make their way into your hydrangea garden. Virescence will kill every hydrangea plant in your garden if you leave it untreated. Milder forms of Virescence won’t lead to noticeable drop-offs, but as it progresses, it will kill the plant.

Hydrangeas with Virescence will have green flowers, and their overall growth is often stunted. They have leafy shoots growing from the flower parts too.

Hydrangea Virescence

How to Treat

While we’d love to present you with a solution to Virescence, the truth is the only thing you can do is remove the infected plants before the disease spreads. To prevent the disease from taking root in the first place, you need to maintain good insect control.

Don’t be afraid to apply an insecticide to keep harmful insects at bay. There are plenty of organic options out there, so you don’t even need to worry about creating a negative environmental impact!

Viruses

There are tons of viruses that infect your hydrangea plants. And while some sites will break down all the different options, since they generally present themselves in the same way and have the same treatment options, we decided to group them all together for you.

Hydrangeas with a virus will have mottled leaves with yellow spotting, and they’ll often have dead flecks and/or line or ringspot patterns.

You also might notice distorted flowers, few flowers, or color breaking. All of these are signs of a sick hydrangea plant, and they’re not something you want to ignore.

How to Treat

Unfortunately, you can’t save a hydrangea plant that has a virus. You need to remove the infected plants before they can spread the virus to the rest of the garden.

However, there are many virus-indexed hydrangeas that are more virus resistant. If you replace the infected plants with virus-indexed hydrangeas, the chances of you having to deal with the problem again drops dramatically.

Furthermore, you need to maintain good insect and mite control to prevent the viruses from arriving in the first place. You can spray with a preventative organic insecticide to keep the plants from getting the virus in the first place.

Other Causes of Hydrangea Distress

While we highlighted the most common diseases that can ail your hydrangea plants, those aren’t the only reasons your plants might be struggling a bit. Below we’ve highlighted three other things that could be giving your hydrangea problems.

Root Rot

While water certainly helps your plants grow, the roots need time to dry out too. Roots that are constantly wet are prone to rot, and once rot sets in, there’s not much you can do.

Stick to a consistent watering schedule, making sure to account for rain. The roots need to dry out some, so ensure you’re not watering late in the day or overwatering on cool days.

Dehydration

hydrangea Dehydration

While too much water can be a problem, so can too little. Plants that don’t get enough water die. When you have plants in dried-out soil, you need to shock the system with some extra water.

If the plants are outside simply water a ton if they’re dry. If it’s a potted plant, try soaking the roots in a larger body of water, like a tub or a sink. Don’t leave them in too long, but a few hours with some extra water will go a long way in keeping your plants alive.

Improper Sunlight

Hydrangeas are very particular about the amount of sunlight they receive each day. They need at least three hours of shade for the best flower growth. If you can put them in a spot where they get sunlight in the early morning but not during the middle of the afternoon, you’ll get the best possible results.


FAQ

If you still have a few questions after reading this guide, you’re not alone. That’s why we decided to answer some of the most frequently asked questions for you here.

How Do You Treat a Sick Hydrangea?

It depends on what’s making the hydrangea sick, but it’s always a good idea to apply a fungicide if your hydrangeas are sick. From there, you might need to increase watering if your plant is dried out, or cut back for a few days if there’s a fungal infection.

It all depends on what’s going on with your plant, so we recommend checking out the rest of this guide to help you determine what’s ailing your plant in the first place.

Why Are Hydrangea Leaves Turning Brown?

When hydrangea leaves are turning brown, it typically means they’re dying. This can happen from natural causes, or it can be a sign of Botrytis blight, Cercospora leaf spot, underwatering, or even a virus.

The exact treatment depends on the cause of your hydrangea leaves turning brown in the first place.

Can I Spray Hydrangea With Soapy Water?

As long as you don’t use too much soap in the mixture, or spray too often, then you can spray hydrangeas with soapy water to ward off an array of problems. They can help deter slugs, ward off some diseases, and more. Simply mix a teaspoon of dish soap with a quart of water and spray away!

Should I Cut Off Dead Hydrangea Flowers?

Absolutely! Removing dead flowers helps keep your hydrangeas blooming longer and encourages new growth. However, in mid to late fall you should leave the dead hydrangea flowers in place. At this point, new flowers won’t grow either way, and keeping the dead flowers can help protect the entire plant.

What Bugs Are Attracted to Hydrangea?

The most common bugs that come to check out hydrangeas are bees, flies, and wasps. That’s because hydrangeas are heavy pollen and nectar creators, and these insects can’t help but come check it out.

However, other bugs that can come to hang out on your hydrangeas include slugs, aphids, ants, beetles, and mites.

How Do I Get Rid of Bugs on My Hydrangea?

The best way to keep harmful bugs off your hydrangeas is to spray them with an organic insecticide. These products can keep harmful bugs off your hydrangeas, but they don’t harm bees and other helpful pollinators!


Final Thoughts

If you want to keep your hydrangeas in check, you need to know about what diseases are out there, and you need to care for them in a way that keeps them from cropping up in the first place.

Fungicides and insecticides are great ways to keep your plants healthy, just ensure that you pick the right ones and don’t overdo it! But by applying preventive measures, you can keep your hydrangeas healthy in the first place, and that’s better than trying to treat sick plants after the fact!

Leave a Comment