Azalea Leaves Turning Yellow

Azalea leaves turning yellow is a common concern. It can be caused by a weak root system, but it can also be caused by the plant not having enough iron. Our red clay soils contain a lot of iron, but they may not be chemically accessible to the plants. The amount of iron available is determined by the acidity of the soil.

The pH scale is used to detect acidity; azaleas prefer soil with a pH range of 5.0 to 5.5. Your azalea won’t be able to absorb iron if the pH of the soil is off. To “acidify” the soil for azaleas and rhododendrons, numerous fertilizer products are marketed. However, it is a scientific reality that ALL fertilizer acidifies the soil to some extent.

In practice, the substance you’re using somewhat acidifies the soil more than conventional powdered fertilizer, but not enough to make a significant impact. In truth, while fertilizer does acidify the ground, the process is so slow that you won’t see any results for years, if at all.

Your azalea will not be able to absorb iron if the pH of the soil is off. For azaleas and rhododendrons, numerous fertilizer products are offered to “acidify” the soil. However, it is a scientific reality that ALL fertilizers acidify the soil to some degree.

In practice, the substance you’re using somewhat acidifies the soil slightly more than conventional powdered fertilizers, but not by enough to make a significant impact. Even if fertilizers do acidify the soil, the process is so slow that you won’t see effects for years, if at all.

Don’t get too excited if the Azalea leaves on your bonsai tree start to turn yellow. You may not have anything to be concerned about, and most of the issues may be resolved quickly. It’s possible that you’ll have to wait a while for the adjustments to take effect, so be patient.

Seasonal Changes

You may not be aware that Azaleas come in two varieties: evergreen and deciduous. When winter hits, perhaps even in April, the leaves of the latter will turn yellow and fall. There’s nothing you can do about it because it’s a natural event. There should be no change in leaf color, particularly to yellow, on evergreen Azaleas. You clearly have an issue since it should be green all year. If you’re still having trouble, try one of the additional explanations listed below.

Change of Location

Many bonsai plants despise being moved from one climate or location to another. They settle in and utilize the circumstances to flourish once they’ve grown accustomed to a new environment. Sudden variations in sunlight and humidity lead it to get stressed, which causes the leaves to turn yellow and fall off.

Nitrogen deficiency

Nitrogen is required for the formation of robust, healthy green leaves on your Azalea. The leaves will turn yellow and perish if there is a lack of this macronutrient in the soil. When a bonsai has been in the soil for more than a year and has absorbed all of the available nitrogen, this happens. If you’re mulching with items that haven’t fully decomposed yet, you may have a nitrogen deficiency. As part of the decomposition process, it draws nitrogen from the soil, leaving less accessible for your Azalea. Before putting mulch to the soil, it’s best to let it decompose entirely.

Soil that is alkaline    

Chlorophyll is the substance that gives your leaves their green color. Iron is one of the nutrients required for the production of this element. Chlorosis is a condition in which your bonsai has an iron deficit, which causes your Azalea leaves to become yellow.  So, how does this relate to alkaline soil? The Azalea’s capacity to take iron from the soil is harmed by the high pH level. When you utilize lime or chalky soil, the similar issue arises. If you want to see the leaves become green again, you need keep the pH below 6.

Inadequate Water  

Azaleas are sensitive to high temperatures and drought-like circumstances, and when there isn’t enough water or humidity, they get stressed. When summer arrives, it’s preferable to water the soil once a week and then wait until the soil dries up before watering it again. Another reason your Azalea leaves are going yellow is if the water in the container is drained too rapidly. The heat will quickly evaporate the liquid, leaving your bonsai tree thirsty. If this happens, you’ll need to figure out how to keep the liquid from spilling out.

Drainage Issues

Finally, you can have a problem with the soil not draining quickly enough. It causes root rot, which is one of the reasons becoming azalea leaves turning yellow like cucumber plant yellow leaves. It indicates that your bonsai is unable to absorb nutrients adequately, which might result in harm to the trunk and branches.

How do you treat azalea leaves turning yellow?

We’ll demonstrate how to improve the situation. Once you’ve figured out what’s causing the problem, you can solve it with one of these approaches.

Iron and nitrogen-rich foods should be available:

If the issue is a shortage of nutrients, you should purchase fertilizer designed exclusively for Azalea bonsais. They’re designed to provide the soil the right amount of nitrogen and iron. However, you should not put your faith in it to do the task. Always examine the container’s ratios and percentages to make sure there’s more nitrogen and iron than other ingredients.

Water More Regularly:

When the leaves turn yellow in the middle of summer, we recommend watering them more than normal. The bath will be enjoyed by your Azalea, especially if you spray the leaves to chill them down and provide humidity. Before you add extra dirt, examine it with your finger to see whether it’s dry.

You don’t want to contribute to root rot. The most prevalent cause of underwatering that we’ve discovered is when customers utilize irrigation systems to water all of their bonsais at once. Different species require different amounts of water, and your Azalea may be deficient.

It’s preferable to attend to each of your trees separately to ensure that they receive exactly what they need. If you wish to employ irrigation systems for your bonsai, group bonsai trees that have similar watering requirements together. These species can be watered for longer periods of time than others that don’t require as much. You can avoid root rot in slow-drinking bonsais this way.

Mulch or provide ample drainage

You can solve either problem if the earth drains water too rapidly or too slowly. They may place drainage rocks at the bottom of the soil to help the water drain more quickly. You won’t have to worry about illnesses because the roots won’t sit in the liquid.

You can apply mulch to the surface to create a condition where you wish to retain moisture instead. It prevents heat and sunshine from frying the substrate and evaporating the fluids required by your Azalea bonsai.

Increase the level of acidity

If the pH is too high, adding extra iron to the soil won’t help since the roots won’t be able to absorb it correctly. You can utilize products that raise iron levels if you’re employing mulch to preserve moisture. Pine bark, for example, is excellent for decreasing pH levels.

You may also use fertilizers to aid with acidity levels, but we prefer a more natural method. Crush some eggshells or add composted banana peels to the soil to aid in the process. You may also use coffee grounds, but this may clash with your goal to add nitrogen, since the two don’t mix well, especially when it comes to flower development.

Move it to a brighter location

Finally, we propose that you evaluate the light conditions in the area where your Azalea bonsai has been planted. It isn’t getting enough sunlight if the light is low, and the leaves will turn yellow. In the spring and summer, it’s preferable to leave them outside.

Keep in mind that deciduous Azaleas lose their leaves in the winter. We realize, though, that you’ll want to bring your evergreen version indoors to avoid frost damage. By placing it near a window, you may still give it with morning sunshine.

Azalea leaves turning red   

Azalea leaves turn red as a result of environmental stress. This might be due to a variety of circumstances, the most prevalent of which being excessive sunshine exposure or overwatering. Azaleas may also generate anthocyanin, a crimson pigment that protects them from stress.


Anthocyanins are produced by plants when they are stressed for any cause. They are red or purple pigments that protect plants against injury in a variety of ways. The particular processes by which anthocyanins protect plants are still being investigated. (Photo courtesy of DePauw University)

Anthocyanins have been found to protect plants from UV radiation in sunshine and to improve photosynthetic efficiency in low light conditions. Plants are protected by anthocyanins from cold temperatures, predators, and excessively acidic or alkaline soils.

Leaf Spot Infections

Red, yellow, or brown stains on your plant’s leaves might be caused by a variety of fungal and bacterial infections. The dots may be a mix of all of these hues, with brown in the middle and yellow and red on the perimeter. While the organisms that cause these issues vary, poor watering tactics or significant rain exposure are frequently the culprits.

When spores or bacteria-infected water splashes onto a plant’s leaves, such as during heavy rain or when the plant is watered carelessly from above, the organisms can quickly take hold and cause difficulties for your plant.

The severity of these illnesses is determined by the organism. Your plant’s red pigmentation is always a clue that it’s battling something. It’s most likely a fungal or bacterial leaf spot illness if you observe brown or yellow patches as well.

Deficiency in Nutrients

Azaleas are not heavy feeders, but they do require a variety of minerals to thrive, including phosphorus, nitrogen, magnesium, and iron.

If these nutrients are insufficient, the plant will show signs of delayed or stunted development, which might be light, yellow, red, or extremely dark green. When growing Azaleas, keep in mind that they require acidic soil to absorb nutrients well.

Too Much Sun  

Azaleas thrive in areas with dappled light and shadow, and where their leaves aren’t exposed to too much direct sunshine.

When a plant’s leaves receive too much direct sunlight, the function of the leaf is harmed, and the cells begin to collapse, causing the leaves to curl and finally fall off the plant.

If the solar damage isn’t too severe, for example, if the plant is burned for an hour a day for a long time, the leaves will get dark red before drying out and becoming brown. The plant generates anthocyanins, which give the leaves their red color and protect them from the sun’s damaging UV radiation.

Azalea leaves turning yellow with black spot        

A pest infestation is usually indicated by black spots on the azalea shrub’s leaves, It looks the same as black spots on cherry tomatoes.. The azalea whitefly and azalea lace wing  both feed on the sap of the shrub by piercing its foliage and sucking the nutrients. Although the azalea whitefly prefers the snow azalea, it can be found on other varieties as well.

On the lower leaves, Azalea whitefly nymphs produce a honeydew-like substance. As the bug infestation becomes worse, the honeydew develops a dark sooty mold. The leaves seem cupped and deformed. Over time, the leaves may droop and become yellow.

The nymphs appear as yellow-white, flat-bodied insects on the underside of the leaves. The adult whitefly has the appearance of a little moth-like bug that flies quickly. When the azalea shrub’s branches are shook, the insects fly off the stems, but the nymphs stay.

Azalea leaves turning yellow with brown spots           

Brown patches on Azalea leaves are often caused by fungal leaf spot infections, leaf miner insects, or sun damage.

Leaf Spots Caused by Fungi

The Issue: Leaves with brown patches that look like irregular polka dots are most likely infected with a fungal infection. The patches might be reddish or practically black in color, with little black specks in the midst. Leaves that have been affected may fall off.

What’s Causing the Issue: Brown spots on leaves are caused by a variety of fungal illnesses, but they’re all treated the same manner. Although small, immature Azaleas occasionally experience a detrimental amount of leaf loss, this sort of fungal infection isn’t usually a serious problem for the plant.

The Solution: Prune away the afflicted regions as soon as flowering is complete. Rake up any spotted leaves that have fallen to the ground. To prevent the illness from spreading, dispose of or burn the spotted leaves. Because this form of fungus spreads by water, irrigate your Azaleas from the ground up rather than getting the leaves wet.

You can apply an all-purpose fungicide if the leaf spot infection is severe, but it isn’t normally essential. Because the fungicide is mostly a preventative, spray it on leaves that haven’t been infected yet, especially new growth.

Leaf miners

The Issue: A few brown patches on various leaves, as well as curled brown tips, may suggest leaf miners. They normally appear in the spring and spread throughout the summer. Some of the afflicted leaves become yellow or brown and fall off.

The Azalea leaf miner an insect that feeds on Azalea leaves, is the source of the problem. The caterpillar lives in “mines,” which are little pockets in the leaves that resemble brown patches or blotches. Mines are frequently found along the leaf’s central vein. Older caterpillars eat the tops of leaves and wrap their webbing around them.

Leaf miners are little yellow or tan moths with purple patterns that are about half an inch long as adults. The caterpillars are around the same size and color.

Scald of the Sun

The Issue: Brown, brown, or yellow splotches on Azalea leaves, especially on the side that receives the most sun, might signal that your Azalea is overheating. The spots will appear on the tops of the leaves rather than the bases, and will not appear on lower or inner leaves shaded by the Azalea.

What’s Causing the Issue: Azaleas don’t perform well in direct sunlight. They like midday shade or sun filtered through the leaves of trees above them. Too much sun may dry up leaves and flowers, causing them to wilt.

The Solution: You won’t be able to repair the damaged leaves, but you can take efforts to safeguard the Azalea in the future. The simplest option is to relocate the Azalea to a more protected location. Another alternative is to plant a tree or a tall shrub to provide shade for the Azalea in question.

Azalea leaves in winter          

Winter damage might be the cause if a few branches on your Azalea have turned brown, or if the tips and margins of the leaves have turned brown, especially if you had very cold winter weather. Even if the damage has been done for months, the symptoms of a cold injury may not appear until spring or summer.

Other signs of winter harm include split bark and dark or black buds. Many Azalea cultivars are sensitive to cold winters, especially if plants are overly exposed to sun or wind. When the plant can’t absorb water from the frozen ground, azalea leaves might get overly dry. Because the problem is primarily one of drought, Azaleas can be harmed by both abnormally mild and extremely harsh winters, depending on the circumstances.

The Solution: There’s little you can do to repair the harm after it’s been done, but the Azalea may recover on its own. Wait till the remainder of the plant has leafed out and blossomed before pruning any dead branches off.

Azalea leaves turning brown   

Anything that destroys Azalea leaves might cause them to become brown since leaves turn brown when they die. Look for other indications to assist you pinpoint the problem if you detect brown leaves on your Azalea. I’ll go through some of the reasons for brown leaves on Azaleas that don’t have many other symptoms.


In the fall, some Azaleas turn brown on their own. Before winter, deciduous Azaleas lose their leaves, and evergreen Azaleas can lose some of their foliage as well. It’s common for the leaves of some Azalea cultivars to turn brown this time of year.

Insufficient Water      

Azalea leaves that have become brown or yellow – or brown at the tips and margins – and are droopy, wilted, or curled might signal that the Azalea isn’t getting enough water. If these symptoms appear when there hasn’t been much rain and you haven’t been watering, give your Azaleas a drink and see if they improve.

Deficiencies in Nutrients

Potassium or calcium deficiency might be indicated by brown leaf tips or margins. Either there aren’t enough of these nutrients in the soil, or the Azalea isn’t able to absorb them. Leaf yellowing is also caused by nutrient deficits, therefore I’ve included them in the section on yellow leaves.

Issues at the Source   

An Azalea with dark leaves or brown tips and margins may be experiencing root difficulties. Root rot, stunt nematode, fertilizer burn, and overwatering or inadequate soil drainage are all possibilities. Other root-related symptoms include light green or yellow leaves, a wilted look, and slowed growth, which can affect the entire plant or just one area.


The Issue: You may have a branch dieback problem if the leaves on certain branches of your Azalea are turning brown and withering.

The Solution: Fungicides and insecticides are ineffective in treating dieback. If you remove the afflicted branches, the remainder of the plant should be OK. To prevent the issue from spreading, carefully remove contaminated plant portions. Azaleas are susceptible to Phytophthora, while other forms of dieback are less dangerous.


The azalea leaves turning yellow for a variety of reasons. Azaleas with fading leaf have been either under or overwatered, or are in the wrong soil. When the plant’s leaves become yellow, it might indicate a nitrogen deficiency or an alkaline environment.

With azalea leaves turning yellow, you’ll want to pay additional attention to any of the concerns listed above. You won’t be able to salvage the bonsai tree if it’s too far gone, so fix it now before it’s too late. Another risk is fungus twig canker.

Canker diseases cause sunken, withering sores on the bark by infecting stems and twigs. Look for sores on the branches that are becoming azalea leaves turning yellow. There is no way to stop a branch from dying back. Simply trim and eliminate any damaged branches. To prevent disease transmission, sanitize pruners with rubbing alcohol between cuts.

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