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Why are Hydrangea Leaves Falling Off?

Hydrangea leaves falling off can be a sign of a problem, but it can also be a natural consequence of seasonal changes. There are several reasons for foliage loss in hydrangeas that I’m going to discuss.

Some of the leaf loss issues in hydrangeas can be prevented with a bit of attention and foresight. I’m going to discuss the most common causes of leaf loss in hydrangeas and offer solutions on how to prevent them from happening in the future.

Causes of Foliage Loss in Hydrangeas

Foliage loss in spring or summer is not normal for hydrangeas. Therefore, leaf loss is almost always caused by environmental factors such as changes in temperature, watering issues, sun exposure or diseases.

There are several things that can cause your hydrangea’s leaves to fall off including:

1. Dehydration

The leaves of hydrangeas that are constantly under-watered can turn yellow, become droopy, and fall off.

The soil of your hydrangeas should be kept moist. In heat waves or when hydrangeas are planted in full sun, the soil can quickly become bone dry.

When this happens, hydrangeas can easily lose their foliage because of dehydration.

2. Sunburn

Apart from the dehydration caused by high temperatures, hydrangeas that have been moved outside from indoors without acclimation or hydrangeas that don’t tolerate full sun can lose their leaves because of too much sun.

While some hydrangeas do enjoy full sun, especially in cooler climates, ideally, they should not be exposed to hot, burning sunlight.

Hydrangeas losing their leaves because of sunburn is especially common in hydrangeas that have been grown indoors. The sudden exposure to direct sunlight can have this effect on hydrangeas.

3. Overwatering

It’s not just dehydration that’s to blame for leaves falling off your hydrangea. Sometimes it’s the opposite that causes trouble — overwatering.

When constantly overwatered or if planted in soil with poor drainage, a hydrangea’s roots may start to rot, cutting off the supply of nutrients to leaves and blooms.

While you should not allow the soil of hydrangeas to completely dry off, you should also not let it sit in water.

4. Frost

If you’ve transplanted a hydrangea to the garden in early spring, a late frost can cause the plant to lose its leaves and buds.

This is why it’s important to transplant hydrangeas only when they’re dormant or when there’s no chance of a late frost damaging new growths.

5. Transplant shock

If you’re transplanting hydrangeas in mid-spring or summer, transplant shock can also cause leaf loss and even bloom loss.

This is one of the reasons why it’s best to schedule any transplanting or hydrangea planting to when the plant is dormant.

6. Pests

Hydrangeas aren’t prone to pest problems as much as other garden plants, but when under siege from certain pests such as aphids or spider mites, hydrangeas can lose their leaves if the infestation is serious enough and it’s left unchecked.

7. Fungal diseases

Some hydrangea fungal diseases can also result in leaf loss if it’s untreated. Fungal diseases are notoriously easier to prevent than to treat, so make sure you follow my disease prevention tips.

These are the most common reasons why hydrangea leaves fall off. Now let’s see what you can do to prevent these.

Prevent Hydrangea Leaves from Falling Off

To prevent hydrangea foliage loss, there are a few preventative measures you must take. Based on what’s causing foliage loss in hydrangeas, I have the following recommendations and tips.

  • To prevent leaf loss caused by watering issues, make sure you plant your hydrangea in a location where water will percolate easily and not sit around the roots. Keep the soil moist and water more frequently in summer heat waves.
  • If moving a potted hydrangea from indoors to the garden, slowly acclimate the plant by extending the length of time it stays outside by a little more each day
  • Plant your hydrangea in a location where it will get full sun in the first part of the day and then semi-shade or dappled sun in the afternoon
  • If you’ve built a winter protection for your hydrangea, make sure not to remove the protection too early in spring to prevent damage from a potential late frost.
  • Transplant hydrangeas in the fall, after the plant finishes blooming and loses its leaves, or in early spring, before it puts out new growths
  • Address any pest issues by spraying your hydrangeas with organic insecticides
  • Keep the shrubs well aerated (trimming, removing spent blooms, removing dead canes, etc.) to reduce the incidence of fungal diseases
  • Plant hydrangea shrubs at a 4-6 feet distance from one another to prevent the spread of diseases and pests
  • Water hydrangeas at the root level and not from above to keep off moisture from the leaves
  • When trimming hydrangeas, sterilize blades between cuts to prevent the transfer of pests and diseases from one plant to another

By following these recommendations, you can minimize the incidence of foliage loss problems in your hydrangeas, especially since some of the issues can prove to be much harder to treat than to prevent.

Do Hydrangeas Lose Their Leaves & Stems in the Fall?

Yes, because hydrangeas are deciduous perennials, they lose their leaves and their new, soft growths in the fall as the plant enters a dormancy phase that lasts from fall to spring.

Therefore, this is a natural cause of foliage loss that should not cause concern. Your hydrangea will come back in the spring with new leaves and growths.

Wrap Up

Hydrangeas have specific requirements that must be met to ensure the plant will thrive. Because watering and location influence how well your hydrangea grows and develops, it’s important to get them right.

Likewise, frost, diseases, transplant shock can also cause foliage loss. Depending on the severity of the problem, leaves may take a while to grow back and blooming may be affected too.

In cases of root rot or severe dehydration, leaf loss may not be the only issue. The plant can even die if the problem is caught too late.

Therefore, make sure you follow the tips and recommendations from above to prevent damage and harm to your hydrangeas.

Updated: March 4, 2021

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