Why Is My Azalea Turning Black? Solve It Fast!

Azaleas are plants that are quite hardy and have just basic requirements. Though in some cases, Azaleas can start to turn black and you might wonder about the reasons and how you can rejuvenate them.

Finding the solution fast is necessary. Since the next step for the plants is usually death!

Reasons for azalea turning black are

  1. Incorrect Watering
  2. Excessive Fertilizing/Wrong Fertilizer
  3. Incorrect Location (Lacking Sunlight or Shade)
  4. Infection By Select Fungal Species 
  5. Incompatible Temperature 
  6. Poor Soil pH 

Let us look into the detailed reasons as to why azaleas turn black and the possible solutions that you can deploy.

Incorrect Watering

Watering and watering correctly is an important part of caring for any plant.

Water any more and you may kill your plants. But, watering less may also endanger your plants or even stunt them. Unfortunately, this is not the worst. Your azaleas can turn black!

Incorrect watering happens to be the leading cause behind azalea leaves turning black.

If you are a new azalea gardener, you’ll be upset to hear there is no azalea watering schedule. There is no strict guide to follow and you will have to make your own. 

How much should you water azaleas? This depends on what azaleas want when it comes down to the water. Azaleas like moist soil. 

Hence you should water them often enough with the right amount of water to keep the soil moist. This often means testing the soil first. Luckily azaleas have shallow root systems so moisture doesn’t have to extend very deeply.

If soil is moist, even for a few inches, avoid watering till it dries out (but not all the way through).

On the basis of season and climate, azaleas will require differing watering efforts. More water in summer but less water in winter is a good rule to go by.

Read why Azaleas turn red 


Here are a few tips for correctly watering azaleas and preventing them from turning black. 

  • Water azaleas only when they are almost completely dry. 
  • Beforehand, make sure the soil drains well enough. Add sand/perlite if it is heavy and collects water.
  • Preferably use bottles/mineral water or rainwater for azaleas. 
  • Avoid using heavy water as it has Sodium Bicarbonate which can harm azalea plants. It makes soil alkaline and unsuitable for azaleas among other plants. 
  • When soaking azalea pots. Make sure to take them out of the water when bubbles stop emerging. 

Soil Plays A Role In Watering 

How does soil affect azalea watering efforts? Well, if the soil is of inadequate quality, even correct watering efforts will result in black azalea leaves. 

Poor drainage due to too much clay or heavy soil materials can hold too much water. This in turn will cause the rotting of your azalea’s roots. Leaf discoloration will accompany the rotting of roots. 

To facilitate your soil to drain well, add sand and perlite to poorly draining soil. Or, choose to use loamy soil which has characteristics appropriate for growing azaleas. 

Choose The Right Water For Azaleas! 

Using the wrong water for your azaleas can possibly alter soil conditions. Particularly the pH of the soil. Azaleas like acidic soil. 

But, hard water has high amounts of Sodium Bicarbonate. This can potentially poison your azaleas. Plus, it increases the soil pH. This means knowing what type of water you are using for watering is essential. 

Instead of hard water, you should use either bottled/mineral water or else rainwater.

The water you collect from rainfall is usually the best type of water for azaleas. So, try and collect quite a bit of it! 

Excessive Fertilizing/Wrong Fertilizer

A common misconception is that fertilizer helps every plant grow. And grow faster at that!

Though azaleas are heavy feeders, they rarely require feeding using fertilizer. The soil can be improved to include more nutrients. 

Overuse of fertilizer can spell trouble. Blackening of azalea leaves is also a possible side-effect of using the wrong type of fertilizer. Usually, a more natural substitute like mulch or compost is better for azaleas. 

Do azaleas like coffee grounds? Find out. 

Correct Use of Fertilizer For Azaleas

Use fertilizer on azaleas sparingly.

Plus you should only use it if you are sure it is the right one. It should contain the appropriate minerals in reasonable amounts.

Follow these tips for choosing the right azalea fertilizer, and using it correctly. 

  • Only in Spring when you notice new shoots and buds should you use fertilizer.
  • Choose a phosphorus based fertilizer that is Acidic.
  • A water-soluble fertilizer is most ideal for azaleas. 
  • Fertilizing the plants at an interval of 2 to 3 weeks is too much. 
  • Do not apply fertilizer during winter. You do not want it to grow shoots and buds. This is because this growth will be increasingly vulnerable to the cold.

Incorrect Location (Lacking Sunlight or Shade)

Putting your azaleas in the best location is usually tough for gardeners. Sometimes it’s because the garden fails to create an ‘ideal spot’. 

But, finding the right location is important. This is because sunlight assists photosynthesis. Besides, too much shade can cause azalea leaf blackening! If it means moving your azalea pot around, you have to do it! 

If your plant is in the ground, you have to observe the spot carefully.

Ensure it gets enough sun and shade to fulfill the azalea’s requirement. Otherwise, a lack of either could mean scorching or stunted growth. 

Finding the Right Location

Having a healthy azalea plant with green leaves means getting it enough of all elements. How much sun should azaleas get? This usually depends on the climate.

  • Azaleas should only have 4 to 6 hours of sun in hot climates. But, a higher 8 to 10 hours are mandatory when in cooler climates.
  • In addition to this, a few hours of shade are also necessary. 
  • It is best to give your azaleas sun in the morning and shade in the afternoon. This is because the morning sun is mild but the afternoon sun may be too hot.
  • As seasons change, so will the location of your azaleas. This is so they get more sun or shade. 

Infection By Select Fungal Species 

It’s not just unsatisfactory conditions that can be the cause of your azalea leaves blackening.

Another issue that results in the same condition is fungal infections. But, only some fungal species may bring about such an alarming symptom! 

There are particularly two fungus-initiated diseases that can make your azalea leaves turn very very dark! 

Cylindrocladium blight

This disease can be due to Cylindrocladium scoparium. 

Leaves usually develop spots and start turning color to black/brown. After which they fall off, all this can occur within a 3 to 4-day window. It is possible that all other parts (stems and roots) also become affected. 

Rhizoctonia blight 

The fungus Rhizoctonia Solani causes this disease in azaleas.

Initial symptoms display as random spots on leaves. However, these spots quickly turn to discoloration of the leaves. They rapidly go from green to brown and eventually black. After this, they will fall off as well. 

Controlling Leaf Blackening Fungus In Azaleas

Both diseases already have spores in the soil. Or even the air, or on the plant itself! It is up to you to prevent suitable environments for them.

And ultimately stop their spread. In both cases, warm and moist conditions favor fungal growth. This is usually at the beginning of winter. 

Also, limit excessive watering, and increase plant spacing to avoid harboring fungi and bacteria. 

Follow these methods of removing and controlling fungal diseases. 

  • For Cylindrocladium blight, using a sterilized blade, cut off affected and dead foliage. Also, this includes leaves and stems. 
  • For Rhizoctonia blight. Remove dead foliage immediately. After this, alter conditions so that they are no longer satisfactory for fungal growth. 

Incompatible Temperature 

Azaleas cannot grow their best when they are in an extremely hot climate or a very cold one.

They prefer moderate temperatures. To be precise, the temperature should never exceed 80℃ (26.7℉).

Unable to accommodate the temperature for your azaleas? This is a leading reason for leaf color change. They can become yellow, brown, and even black. This is in severely bad and inappropriate conditions. 

Best Temperature to Grow Azaleas

Azaleas need both sun and shade. This also comes with certain temperature requirements. Lower temperatures in a hot climate and higher temperatures in a cooler climate are ideal. 

The most appropriate azalea growing temperature ranges from 50℉ to 65℉ (10℃ to 18℃). 

Of course, the best temperature at which your azalea will not develop black foliage depends on a few factors. This includes climate, season, and the type of azalea (evergreen or deciduous) you are growing. 

Noticed some ants on your azaleas and wondering if they will stay or go? Find out: do azalea attract azaleas and what they want.

Poor Soil pH 

Azaleas are very particular about the soil pH they require. Anything other than acidic soil may cause unwanted effects.

One of which may be the changing of leaf color. Sadly, this soil characteristic goes unnoticed. Gardeners often don’t discover it until it is too late! 

Sometimes adding a component or two can alter the composition of the soil. Particularly the pH of the soil.

Failure to maintain the acidic pH would impact the azalea plant’s ability to absorb nutrients and minerals.

Correcting Soil pH

So make sure the soil is habitual for your azaleas. You will have to constantly check the soil. You can do so and amend the soil using these tips. 

  • Use a soil pH meter to test the soil’s pH on a regular basis. Especially if azaleas are turning black but all other conditions are perfect.
  • If the pH is too high, you must decrease it immediately.
  • Add substances like Sulfur, Chelated Iron, or Aluminum Sulfur to decrease the pH. 
  • Also, well-rotted compost is acidic and adding it to soil can help manage the soil’s pH levels. 
  • A pH reading of 7 (neutral) is not ideal for your azalea either. You will have to add components to drop the pH level.  


When facing unfavorable conditions, your azaleas may change color. It is up to their gardener to notice the color change. Then, find the issue, and resolve it fast!

Causes for Azalea turning black include Incorrect watering, Excessive fertilizing/Wrong fertilizer, Incorrect location, Fungal infection, Incompatible temperature, and Poor soil pH.

Solutions include watering mindfully, choosing the right fertilizer, moving locations, removing infected matter, and adjusting soil. 


Why is my azalea turning brown? 

Azaleas turn brown for a range of reasons. The most common of them are under/overwatering, lace bug infestations, fungal infections, fertilizer burn, and the sun scorching.

Anyone or a combination of these could cause your azalea to change color. Solving this involves first identifying the reason.