Hydrangeas are lovely old-fashioned garden plants that are undergoing a revival. They’re surprisingly easy to grow and require minimal maintenance. They can tolerate a variety of conditions, including full sun and part shade. Plus, they’re super easy to propagate.
You may notice, though, that your hydrangea leaves sometimes turn brown. There are a variety of reasons for this, including not enough moisture, over-fertilization, or sunburn. Brown leaves can also be caused by a pest infestation from aphids or scale insects or certain fungal and bacterial diseases.
We’ll look at each of these reasons in more detail and tell you how to fix them so that your hydrangeas can look their absolute best.
11 Reasons Why Your Hydrangea Leaves Are Turning Brown
Here are some of the more common reasons why your hydrangea leaves are turning brown.
|Common Reason||How To Recognise||How To Fix|
|Transplant shock||When planting out hydrangeas, loosen the roots gently before planting, and make sure you water well once in the ground.||Give your plant a good soaking at the root level. Avoid getting water on the leaves, as this can cause fungal or bacterial disease problems.|
|Fertilizer Toxicity||The leaves on your hydrangea are wilting and look burned. The leaf edges and tips turn brown.||Drench the soil around your plants with water to wash away any excess fertilizer|
|Sunburn||The edges of the leaves turn brown and shrivel.||Although hydrangeas can live quite happily in full sun, they must also be given adequate moisture. Make sure your plants are getting enough water, and give them some afternoon shade on really hot days.|
|Lack of Water||The leaves start to wilt and then turn brown along the edges||Remove the affected leaves and discard them in the garbage. Avoid getting the leaves wet, and only water your plant at the soil level.|
|Frost Damage||The leaves will start to exhibit brown spots and will eventually turn yellow and drop off the plant.||This is perfectly normal, and your plant will recover in the spring with lovely new green growth.|
|Cercospora Fungal Leaf Spot||Your leaves display small brown or purple-colored spots starting at the base of the plant. The leaves will eventually turn yellow and drop off.||Remove diseased leaves and dispose of them in the garbage. Increase the airflow around your plants. Treat the plant either with a fungicide or make a natural spray using compost tea, liquid kelp, or garlic oil.|
|Anthracnose Fungal Leaf Spot||Your leaves will display large brown spots that have lighter brown centers. The spots may also appear on the flowers.||Remove diseased leaves and dispose of them in the garbage. Increase the airflow around your plants. Treat the plant either with a fungicide or make a natural spray using compost tea, liquid kelp, or garlic oil.|
|Bacterial Leaf Spot||The leaves of your hydrangea exhibit small, irregular-shaped spots that are either purple or red in color. Usually, the lower leaves are affected first. Eventually, the center of the spots will die.||Remove diseased leaves and dispose of them in the garbage. Increase the airflow around your plants. Treat the plant either with a fungicide or make a natural spray using compost tea, liquid kelp, or garlic oil.|
|Hydrangea Rust||The leaves develop orange spots on the undersides.||Remove the infected leaves and place them in the garbage. Avoid getting the leaves wet and only water your plant at the soil level.|
|Aphid Infestation||Leaves start to droop, shrivel and turn brown. When looking closely, you’ll see tiny green insects on the leaves and buds.||Spray your plant with insecticidal soap or a mixture of water and neem oil.|
|Scale Insect Infestation||Leaves will droop and turn brown. You’ll notice dark brown scaly spots along the ribs of the leaves and on the stems. The spots are actually scaled insects.||Spray the plant with a mixture containing insecticidal soap and water. You could also use a mixture of neem oil and water.|
Plants that are purchased from nurseries or garden centers can often display some transplant shock when they’re planted out into the garden. This is quite normal, and the plant will generally recover well.
However, there are some things that you can do to limit the amount of transplant shock for your newly planted hydrangeas.
When you take the plant out of the pot, examine the root ball. If the roots are tightly bound, gently tease them apart so they can spread out in the garden. Make your planting hole large enough so that you can position roots out as far as possible.
Once you’ve filled in the hole, make sure that you water well but only at the root level. Avoid getting the leaves wet. Using a watering can or hose, water the base of the plant and let the water soak in. If the weather is hot, you might want to do this again a couple of hours later.
It’s important to note, however, that you don’t want the soil to be waterlogged. It needs to have adequate drainage so that any excess can easily drain away. Having the roots of your hydrangea sitting in water constantly can promote the development of root rot.
Monitor your plant for the first couple of weeks and water it daily, if necessary.
Over-fertilizing your hydrangea plant can result in the leaves turning brown. This is called fertilizer burn, where the fertilizer is allowed to build up in the soil.
Hydrangeas are generally not heavy feeders, and while some fertilizing will result in more growth and bigger blooms, too much is not good for the plant.
Consider using a liquid fertilizer that is specially formulated for flowering plants, such as hydrangeas, and make sure that you dilute it with water. You should only have to apply this two or three times during the growing season.
Alternatively, you might want to try a slow-release fertilizer that you only apply once a year in spring.
If your plant is suffering from fertilizer burn, the best thing you can do is drench the soil well with water to wash out any excess salts that may have accumulated. However, do make sure that the excess water can drain away freely as waterlogged soil will be low in oxygen and cause further problems for your plant.
There are different varieties of hydrangea, and while some will grow happily in full sun, other varieties prefer some afternoon shade. In fact, some hydrangea varieties grow best when situated in a spot that receives only dappled sunlight.
Many gardeners even grow hydrangeas quite successfully under trees that only let some sunlight through.
If you suspect that your hydrangeas might be suffering from sunburn, consider providing them with some afternoon shade. If you don’t want to move your plants, you can either set up a shade structure or place large plants in pots nearby that will provide your hydrangeas with afternoon shade. This is generally only necessary during the hottest parts of summer when the afternoon sun has a lot of heat.
Another key point to remember when the weather heats up is that your plants will require additional water to cope with the heat. During this time, it might be necessary to water your hydrangeas on a daily basis.
Lack Of Water
It’s no secret that hydrangeas love moist soil. They have large leaves that allow a lot of transpiration in hot weather. Therefore, your plants need to be watered much more frequently when the temperature rises, especially if your plants are growing in full sun.
One of the best things you can do is invest in a moisture meter. You can poke this into the soil around your plants to identify how much moisture is there. Hydrangeas ideally like moist but not wet soil.
In summer, your plants may need watering on a daily basis if the sun is really hot. If you have trouble remembering to water your plants, you could consider installing a drip system on an automatic timer.
A drip system, which directs water directly to the soil at a slow pace, is ideal for plants like hydrangeas. This ensures that the soil is always moist but never too wet. If you set the drip system to operate for a set amount of time every day over the summer, your plants should receive all the water that they need.
Another good idea is to use a soaker hose to water your hydrangeas. A soaker hose is similar to a normal garden hose except that it has a multitude of small holes all along its length. To use a soaker hose, you just lay it on the ground near the base of your plants and attach the end to a water tap.
When you turn on the tap, water drips out at a slow, steady pace from the holes along the hose. If you install a timer on your tap, the water will turn off automatically after a set time.
Alternatively, you can use water spikes, which you attach to an empty soda bottle with the bottom cut off. However, if you use this system, you have to remember to fill the bottle on a daily basis over the summer.
Hydrangeas will start to look quite sad once they’re exposed to the first frosts of the year. However, this is quite normal, and it will not harm the plant in any way. In fact, hydrangeas will grow best in areas where they’re exposed to a number of frosts over winter.
On the other hand, if you get a late frost in spring after your hydrangeas have already started putting on some new growth, you might experience some problems. At this time, the plant has come out of winter dormancy and is less able to withstand really cold temperatures.
The best thing you can do is keep an eye on the weather forecast early in spring. If a late frost is predicted, cover your plants with some fabric or shade cloth to protect them from the freeze.
Cercospora Fungal Leaf Spot
This is a fungal disease that results in purple or brown colored spots on the leaves. Usually, the older leaves at the base of the plant are affected first. The spots are normally ¼ to 1/8 of an inch in diameter. Some spots may have gray or tan centers, or they may have purple halos around the spots.
One of the best ways to prevent fungal diseases is to ensure that you keep the ground under the hydrangeas nice and clean. Clear away any old leaves and spent flowers, and don’t allow them to remain on the ground under the plants. It’s a good idea to give your plants a prune towards the end of fall to remove any dead branches and damaged foliage. This allows for extra airflow and reduces the spread of fungal spores.
Also, ensure that when you’re watering that the water does not splash up onto the leaves. This is because fungal spores generally live in the soil and are spread onto the plant through water splashing.
If your plant does have evidence of a fungal disease, the best thing to do is to remove the diseased leaves and make sure that you throw them in the garbage. Never put these into the compost, as the fungal spores need extremely high heat to be killed.
Remember to sterilize your pruning tools after you do this to kill any fungal spores that you may have picked up, too. And never prune diseased and healthy plant material at the same time without sterilizing your tools first.
If you wish to treat your plants with a fungicide, use one that contains either chlorothalonil or thiophanate-methyl. For more natural control, you can try spraying the plant with either compost tea, a solution of liquid kelp and water, or a solution of garlic oil and water.
Anthracnose Fungal Leaf Spot
This is another fungal disease common to hydrangeas and can be fatal for the plant if not controlled and treated appropriately. This disease causes large brown spots on the leaves that have tan or light brown centers. If the spots also appear on the flowers, then you can be sure that the disease affecting your hydrangeas is indeed Anthracnose.
You should follow the instructions given above for Cercospora fungal leaf spot to help treat or prevent this disease from affecting your plants.
Bacterial Leaf Spot
Bacterial leaf spot is caused by the Xanthomonas campestris pathogen. This disease causes purple or red spots to form on the leaves. Most likely, the disease will affect the older leaves at the base of the plant first.
As these spots grow, they’ll become angular, and the center of the spots will die and fall out.
If you suspect that your hydrangea has been affected by a bacterial leaf spot, remove all of the affected leaves and put them in the garbage.
Spray your plant either with a proprietary fungicide or use one of the natural sprays mentioned above.
Hydrangea rust is another fungal disease that appears as round orange spots on the undersides of the leaves. Eventually, the upper side of the leaves develops brown or yellow spots causing the leaves to die and drop off the plant.
Here are some important preventative measures that you can take to prevent this disease from affecting your plants.
- Never water your plant from above, and avoid splashing water onto the leaves.
- Clean up any debris from beneath the plant on a regular basis.
- Ensure there’s plenty of air circulation around your plants by pruning them regularly.
- Apply a fungicide at the beginning of spring as a preventative measure.
If your plant has become infected with rust disease, here are some steps you can take to minimize the risk of the disease spreading:
- Remove the diseased leaves and dispose of them in the garbage.
- Clear away any debris from underneath the plant.
- Spray the plant with a fungicide and repeat in 14 days.
Aphids are small, green sap-sucking insects that feed on the sap of your plants. Apart from causing damage to the leaves and buds of your plants, they also produce wounds that leave your plant open to infection from fungal and bacterial diseases.
Another problem that is caused by aphids is that they excrete a sticky honeydew substance that sticks to and coats the leaves. This attracts ants because they like to feed on the honeydew. Additionally, a sooty, fungal growth can also form on the honeydew. While this mold is not dangerous to your hydrangea, it can block sunlight from the leaves, which can result in decreased photosynthesis.
There are numerous ways that you can control these insects and stop them from attacking your precious hydrangeas. Here are some steps you can take to rid your plants of these annoying pests.
- As a starting measure, you can easily blast the aphids off with the hose, though they will likely return after a little while.
- Spray the insects with a mixture of dish soap and water. The soap sticks to the insects and suffocates them.
- Use an insecticidal soap mixed with water to spray your plants. You might have to do this a number of times until you have the aphids under control.
- A neem oil solution mixed with water can also be quite helpful in getting rid of the aphids.
It’s important to remember not to spray your plants on a hot day when the sun is blazing, as this will cause further damage. Wait until the late afternoon when the heat of the sun has abated.
Scale Insect Infestation
Scale insects look like small brown bumps on the stems of your plant. They are also sap-sucking insects and will cause damage by interrupting the sap flow from the roots up to the leaves of the plant, causing the leaves to go brown.
Here are signs to look out for if you think your hydrangea is affected by scale insects:
- Evidence of eggs that exhibit as smooth, oval patches covered with white waxy fibers.
- Scale insects that are newly hatched and are pale yellow in color.
- Mature scale insects that are brown and oval in shape.
- Your plant is not growing vigorously, and the leaves are browning and dropping off.
Here are some effective ways to control this insect pest:
- Use an organic spray containing natural pyrethrum to kill the insects. Insecticidal soap works well for this.
- Spray your plants with a mixture containing neem oil and water.
- For small infestations, the adult-scale insects can be wiped off with a soft rag dipped in isopropyl alcohol.
- Encourage predator insects such as ladybirds into your garden.
Good Gardening Practices To Follow To Prevent Your Hydrangea Leaves From Turning Brown
As we’ve now learned, there are many causes for hydrangea leaves to turn brown. We’ve also discovered that there are many good gardening practices that we can follow to prevent this from happening.
Here’s a rundown of the most important things that we can do to keep our hydrangeas lush and green:
- Ensure your hydrangea receives plenty of water in the hottest part of the year.
- Provide your plant with some shade from the scorching afternoon sun.
- Water only the roots of your plant, and avoid getting water on the leaves.
- Install a watering system such as a soaker hose or drip irrigation system to ensure that the plants receive adequate water, primarily down at the soil level.
- Remove debris from beneath your plants on a regular basis to prevent the accumulation of fungal spores.
- Give your plants a tidy up in late fall to remove dead branches and foliage and to open up the plant for better airflow.
- Remember to sterilize your pruning tools regularly to stop the spread of disease from one plant to another.
- Only fertilize your hydrangea sparingly in spring to encourage growth and blooming without adding too much.
- Protect your plants in spring from any late frosts that may be predicted.
- Ensure that the soil is free-draining and does not become waterlogged.
- If you’ve had problems with fungal diseases in the past, apply a fungicide in early spring to avoid further problems.
If you follow all these good gardening practices, you’ll have gorgeous healthy hydrangea plants that will reward you with glorious blooms right throughout the warmer months.