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Top Reasons for Brown Leaves on Rhododendron Plants

Top Reasons for Brown Leaves on Rhododendron Plants

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The Rhododendron plants are known for their beautiful flowers that bloom in clusters. The flowers are one of the main reasons why so many plant enthusiasts want to grow Rhododendrons.

However, Rhododendron plants require a lot of care and attention, which is why many plant experts do not recommend them for beginners.

Even expert growers struggle with finding the right reason behind brown leaves on Rhododendrons.


What Causes Brown Leaves on Rhododendron Plants?

There can be many causes behind brown leaves on Rhododendron plants, such as fertilization issues, water issues, soil issues, insects, and pests. However, just by taking a few precautions, you can easily save your plant’s leaves and help your plant get healthier.


9 Reasons Behind Why Your Rhododendron Plant Has Brown Leaves


Planting the Rhododendron Plant Too Deep

Planting your Rhododendron plants too deep into the soil can cause the edge of your leaves to turn brown. This can also cause your plant to grow fewer flowers.

Rhododendron plants require a significant amount of air at the root level.


Improper Drainage

Bad drainage is also known to cause the leaves of Rhododendron plants to turn brown. This is because bad drainage leads to rotting of the roots, which ends up causing other diseases.

Rhododendron plants require moist soil, and they do not appreciate soggy soil, especially during the winter season. You must always add drainage holes in the pot so that excess water can be removed from the pot.



Root weevil insects are known to chew off the bark of the trunk that is close to ground level.

This only happens when the root weevil insects are in larval form, and it can cause the leaves of your Rhododendron Plant to turn brown.



In order to have healthy leaves, your root system needs to be healthy as well. If the root system has been damaged due to mechanical injuries, then the leaves will suffer the consequences as well.

If you do not use the proper equipment when propagating, repotting, or even pruning your plant, then it can cause the growth of fungus and other diseases.


Summer Drought

Summer drought is a common problem faced by Rhododendron plant owners. This is when your plant is not provided with enough water during the summer season, and it causes the soil to dry up faster.

Summer drought is mostly faced by plant owners who keep their Rhododendron plants outdoors.

However, indoor plant owners can also become overly precautions as well, causing them to water their plants less.



Just as some plant owners can under-water their plants, there are also many who end up over-watering their Rhododendron plants, and this can also cause brown leaves.


Lighting Issues

The leaves of your Rhododendron plants can turn brown if they are kept under direct sunlight. This is because they can also suffer from drought symptoms, even if the plant is being watered regularly.

There are a few Rhododendron plants that can thrive under direct sunlight. But generally, Rhododendron plants are recommended to be kept away from direct sunlight as it can also burn the leaves.


Fertilization Issues

If the leaves of your Rhododendron plants have too much fertilizer applied to them and it has not been washed down into the soil, then salt accumulation will occur.

The fertilizer causes a whitish crust to form on top of the leaves, and this can cause your plant’s leaves to turn brown.


pH Issues

Rhododendron plants are meant to be kept in soil that has an acidic pH of 4.5 to 5.5. However, if the plant is kept in alkaline soil, then the leaves can start to turn brown.

But having a soil pH that is highly acidic (lower than 4 pH) can also cause the plant to suffer.


Solutions for Brown Rhododendron Leaves


Planting at Proper Depth

Planting your Rhododendron plants at the proper depth will help reduce the chances of brown leaves. If your root ball is kept at least one inch above the soil, it can help the roots get enough air and stop them from rotting.


Providing Proper Drainage

When repotting or planting your Rhododendron plants, you need to make sure that the pot has drainage holes in it. If proper drainage holes are not provided, the roots will rot and cause the leaves to turn brown.

Most plant pots already have drainage holes present in them. However, if you do not have one with drainage holes, then you make them with a simple electric drill.


Get Rid of the Insects and Pests

There are many ways to prevent pests and insects from invading your plant. You can use neem oil to get rid of mealybugs and spider mites.

Taking a cotton bud with alcohol present on it can also get rid of several insects and pests. However, spraying your plant with high-pressure soapy water will also get rid of any pests or insects present on it.


Cleaning Equipment

Whenever you prune, propagate or repot your plant, it is important to sanitize every piece of equipment that you use. Equipment can be sanitized by using rubbing alcohol.

Metal and rubber equipment can also be sanitized in boiling water. Simply take a large pot of water and boil it.

Once your see bubbles forming, you can add your equipment into the water and leave it there for half an hour.


Provide Proper Watering

Over-watering and under-watering can be avoided with one simple rule, and that is by checking if at least one inch of the soil has dried up. If one inch of the soil is dry, then it is time to water your plant.

Make sure to often check up on the moistness of the soil during the summer season as the soil becomes dry much faster. Do not water your Rhododendron plant too often in the winter season as it requires less water.


Provide Proper Lighting

Keep your Rhododendron plants under indirect sunlight and close to the window with sheer curtains. Never provide it with direct sunlight as it can cause the leaves to burn.

The afternoon sun is the most damaging, while filtered light or morning light is considered to be the best lighting for Rhododendron plants.



Rhododendron plants need to be provided with fertilizers only during their growing seasons, which is from spring to summer. You must stop fertilizing your plant during winters.

During the growing seasons, make sure to only fertilize the plant once every month.

Fertilize your Rhododendron plant with a diluted fertilizer or slow-releasing fertilizer. Avoid spraying the leaves of the plant with fertilizer since salt formation is the main cause of brown leaves.


Fix pH

Using organic matter can help reduce the acidity of your soil only if it has become too acidic. If the soil has become alkaline, then you can use sulfur to decrease the pH level.


Frequently Asked Questions about Brown Leaves on Rhododendrons


Should I cut off the brown leaves on my Rhododendron plant?

Brown leaves can be cured, but if the leaves still do not recover after following every solution, then pruning them off is a good choice. Cutting the brown leaves off will not harm your plant in any way; in fact, pruning promotes further growth.


Can lace bugs also cause my Rhododendron leaves to turn brown?

Lace bugs are one of the many insects that can harm Rhododendron leaves and cause the leaves to turn brown. However, they often cause the leaves to turn yellow once they have feasted on them.