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8 Causes of Hydrangea Leaves Curling (And How To Fix)

Hey everyone! I’ve been nurturing hydrangeas for a long time, and I’m always learning more. It’s a never-ending journey because nature always throws new challenges our way. Today, let’s chat about a big challenge you might face with hydrangeas.

Watering them just right can be tricky. Too much water, and you’ll see the leaves get soggy and curl. But if you don’t give them enough water, the leaves will curl upwards, like they’re begging for a drink.

Next, you will learn all the possible causes of curling hydrangea leaves.

1. Underwatering

Hydrangea leaves curled because of underwatering.

Hydrangea leaves curled because of underwatering.

Hydrangeas really can’t handle dry soil. Even a short dry spell can affect their leaves, especially during those hot summer days.

When the soil around their roots dries up and they’re under strong sunlight, you’ll notice the tips of the hydrangea leaves start to curl. They might even get burnt spots and turn brown or black.

Here’s what you can do:

  1. Water your hydrangea with about 1-3 gallons of water.
  2. In summer, water when the top inch of soil dries out.
  3. Put some mulch around the root area to help the soil hold onto moisture longer.

2. Pests

Hydrangea leaves curling

Hydrangea leaves curled by Olethreutes ferriferana.

Insects on hydrangea leaves often cause them to deform. These bugs generally fall into two categories based on how they affect the plant.

First, there’s the hydrangea leaftier (Olethreutes ferriferana), a tiny moth. It lays eggs on the leaves, and when the larvae hatch, they start tying young leaves close together with their fibers, creating a leafy cocoon. Inside, the larva feasts on the leaf sap.

The second group includes aphids, mites, and other sucking insects. When there’s a lot of them, the leaves tend to curl up.

Here’s what you can do:

  1. For the hydrangea leaftier, remove the cocoons and larvae from your plant. Remember to burn whatever you take off to prevent reinfestation.
  2. To deal with aphids and mites, spray your hydrangeas with horticultural oil.

Read also: How To Care For Hydrangeas

3. Excessive Sunlight

Too much sun

Hydrangea leaves curling because of too much sunlight.

A whole day in the sun can be too much for your hydrangea, leading to sunburned leaves that start curling at the tips and edges. Eventually, these leaves can turn crispy and drop off. Even the blooms might get sunburned.

Here’s what you can do:

  1. Make sure your hydrangea gets some shade. However, don’t overdo it; it still needs about 4 to 6 hours of morning sunlight.
  2. Give your hydrangea an extra watering session to help it cope with the sun exposure.

4. Frost Damage

Frost damage

Hydrangea leaves curling due to frost damage.

Late frost is a big threat to many plants, including hydrangeas. In spring, when hydrangeas start to unfurl their leaves, a sudden temperature drop can harm them.

If mature leaves are present when the frost strikes, they might get partially damaged, showing black spots. However, they can often survive and continue photosynthesizing for the rest of the season.

Here’s what you can do:

  1. Trim off the damaged parts of the plant.
  2. Give it a one-time watering with a liquid multipurpose fertilizer to help it recover.
  3. To prevent future frost damage, cover your hydrangea with garden fabric if there’s a risk of late frosts.

5. Overwatering

If your hydrangea’s roots sit in water or very damp soil for too long, they’ll start to rot. This means the leaves won’t get enough water, causing them to curl, turn yellow, and eventually fall off.

Here’s what you can do:

  1. Only water your hydrangea when the top 2 inches of soil have dried out.
  2. Mix compost or other organic materials into the existing soil to improve drainage.

6. Diseases

Hydrangea leaves curling because of disease

Hydrangea leaves curling because of disease.

Fungal diseases are a major reason for deformed hydrangea leaves. Anthracnose tops the list, but various molds and rots also play a part. These fungi attack the leaves and mar their appearance.

Here’s what you can do:

  1. Keep your garden tidy. Avoid leaving plant debris around your hydrangeas where it can decay.
  2. Water your plants just enough, and ensure there’s good air circulation in your garden.
  3. Treat your hydrangeas with a fungicide. A copper-based fungicide often works well in these cases.

7. Fertilizer Issues

Lack of phosphorus

Hydrangea leaves curl due to a lack of phosphorus.

When hydrangeas don’t get enough trace elements, particularly phosphorus and calcium, their leaves can start to deform, often curling upwards. Both of these elements are crucial for the plant’s health.

Without enough phosphorus, for example, the hydrangea’s root system struggles, impacting its ability to absorb other minerals. This deficiency can lead to deformed leaves, color changes, or stunted growth.

Here’s what you can do:

  1. First, test the soil’s pH. If it’s too alkaline (above pH 7.5), you’ll need to lower the pH using an acidifier or compost.
  2. Fertilize your hydrangeas in early spring with a slow-release fertilizer.
  3. Consider a second round of fertilization in mid-summer, but not before.
  4. Avoid fertilizing hydrangeas during winter months.

8. Transplant Shock

Hydrangea leaves curled because of transplant shock.

Hydrangea leaves curled because of transplant shock.

Replanting can sometimes lead to transplant shock, a stressful condition for hydrangeas. You can spot this when the leaves become twisted, yellowed, or crispy.

Here’s what you can do:

  1. When transplanting your hydrangea, be as gentle as possible to minimize root damage.
  2. After moving it to its new spot, consider shading it with a garden umbrella for a few weeks. This helps protect the hydrangea from intense sunlight.
  3. Keep the soil consistently moist, but not waterlogged. Make sure it doesn’t dry out more than an inch deep.

Shery Gould

Friday 2nd of June 2023

My hydrangea stems are curling, not the leaves. It’s been a little hot the past couple of days but nothing unusual. I haven’t done anything to the plant and can’t find anything online about this. I can’t seem to add my photo.

Igor Viznyy

Sunday 4th of June 2023

Hi Shery, It's hard to say since I haven't come across anything like this yet. Can you send me a photo at igor.viznyy@gmail.com

If the stems are curling but the leaves are not turning yellow, then nothing is wrong with your hydrangea yet. Make sure you give it a good environment. Also a spray of fungicide and insecticide is a good idea.