It is normal for some old leaves of azaleas to turn red, especially in the fall. However, if new growth or all of your plant’s leaves are red, that’s a sign that the plant is stressed and struggling, and you need to take action to correct the problem.
Environmental stress is the reason why azalea leaves turn red. This can be due to several factors, most commonly overexposure to the sun or too much water. The azalea can also produce a red pigment called anthocyanin to protect against stressors.
In this article, I’ll give you some possible reasons why your azalea might be stressed and give you some tips on how to improve the situation.
Contents
Causes of Azalea Leaves Turning Red
anthocyanins
When a plant is stressed for any reason, it often produces anthocyanins in response. Anthocyanins are red or purple pigments that play several roles in protecting the plant from damage. The exact mechanisms of how anthocyanins protect plants are complex and still under investigation. (Source: DePauw University†
Anthocyanins have been shown to protect plants from the sun’s UV rays and increase the efficiency of photosynthesis in low light conditions.
Anthocyanins also play a role in protecting plants from low temperatures, predators, and highly acidic or alkaline soils.
The solution
Try to avoid stressing your plant. Store it in a stable environment with a temperature that does not regularly exceed 29°C, away from strong drafts and heat sources.
Make sure your plant gets plenty of bright indirect light but limited direct sunlight and place it in acidic, moist, well-drained soil.
leaf spot
Various fungal and bacterial diseases can cause red, yellow or brown spots on your plant’s leaves. The spots can combine any of these colors, often brown in the center with yellow and red on the edges.
Although the organisms that cause these problems are diverse, the cause is usually poor irrigation technique or exposure to heavy rain.
When water contaminated with spores or bacteria is splashed onto a plant’s leaves, such as during heavy rains or when the plant is watered from above, the organisms can take hold and quickly cause problems for your plant.
The severity of these diseases depends on the organism involved. Red pigmentation is always a sign that your plant is fighting something. If you also see brown or yellow spots, it is likely a fungal or bacterial leaf spot.
The solution
Some fungal leaf diseases can be treated with fungicides, but others, along with bacterial leaf spots, are nearly impossible to treat once they appear. It is always better to prevent these diseases than to try to cure them.
The best way to prevent disease in your azaleas is to remove dead leaves and debris from your plant’s pot, as spores and bacteria live here, waiting for a chance to splash onto your plant.
Always make sure that water does not penetrate the leaves and the stem of the plant. Protect it during heavy rains and preferably water the plant from below. This not only minimizes the risk of infection, but also increases the root strength of the plant.
nutrient deficiency
Azaleas don’t eat much, but they need a variety of nutrients, including phosphorus, nitrogen, magnesium, and iron, to be healthy.
If the levels of these nutrients are too low, the plant will exhibit various symptoms, such as slow or stunted growth which may be pale, yellow, red or very dark green.
One important thing to remember when growing azaleas is that they need acidic soil to absorb nutrients effectively.
If your azalea’s leaves are turning red around the edges or in spots, the problem could be one of the following nutrient deficiencies:
| nutrient | deficiency symptom |
| Nitrogen | Pale, stunted new growth with red margins and/or spots on older leaves. |
| Match | Special dark green leaves, developing in dark red spots or stripes along the midrib. |
| Iron | Yellowing of young leaves between the veins, leaving the veins green. The leaves may turn red around the edges or in places. The oldest leaves are the last affected. |
| Magnesium | The leaves turn yellow from the tips, including the veins. Red-violet spots may appear on the upper side of the leaves. |
| Manganese | Symptoms similar to iron deficiency, but less severe. |
The solution
Most nutrient deficiencies are easily remedied by giving the plant more of the nutrient in question. However, it can be difficult to determine which nutrient your plant is lacking. One option is to have your soil tested in the lab, which will give you insight into the nutrients in the soil.
If you go this route, it’s important to remember that azaleas need acidic soil to access nutrients: the soil can be full of nutrients, but if it’s too alkaline, the plant won’t be able to use it. absorb properly.
Because azaleas like acidic soil between pH 4.5 and 5.5, it’s best to use potting soil that has been developed especially for acid-loving plants.
This will allow your plant to absorb the nutrients it needs, and you won’t have to do much more than feed it once a year in the spring, again with a fertilizer designed for acid lovers.
Always follow directions and don’t be tempted to overfeed your plant as this can burn the plant’s roots and cause other problems.
If your plant is potted with general-purpose compost or alkaline soil, you will likely need to acidify it. You can use a light application of ferrous sulfate to lower the pH. Never use aluminum sulfate as it is toxic to azaleas.
a lot of sun
Azaleas are happiest in a spot with dappled light and shade, where they don’t get too much direct sunlight on their leaves.
When too much sunlight hits the leaves of a plant, it affects the function of the leaves and the cells begin to collapse causing the leaves to curl up and eventually fall off the plant.
If the sun damage is not so severe, for example if the plant burns for an hour a day for a long time, you can be warned that there is a problem: the leaves turn dark red sooner to dry out and brown.
The plant produces anthocyanins which protect the leaves from the sun’s harmful UV rays, giving them a red appearance.
However, if the sun damage is very severe, say several days of hot, direct summer sun, the plant may not survive; it won’t have time to produce its natural anthocyanin-based sunscreen and your leaves will burn quickly; they will dry out and turn brown before falling. outside the factory.
The solution
Place your azalea in a location with plenty of bright but indirect light, with no more than a few hours per day of direct sunlight on the leaves.
Never place your plant on a windowsill or very close to a window as it is prone to sunburn – window glass amplifies the sun’s rays, which means they will burn your plant very quickly.
If you keep your plant in a place where it receives direct sunlight, make sure it is several feet away from the window.
lack of light
Although they appreciate a fairly shady position, azaleas do not do well in deep shade. If they don’t get enough light, they produce anthocyanins which help the plant increase the efficiency of photosynthesis. You may notice the leaves turn a deep red color and lean towards the nearest light source.
The solution
Make sure your azalea gets bright, indirect light for at least 8-10 hours a day. If you notice your plant leaning toward the light or the leaves turning from darker green to red, move it to a brighter spot.
under or on water
Azaleas like consistently moist, well-drained soil. If the soil is too wet or too dry, the plant will be stressed and the leaves will turn red due to the production of anthocyanins.
In either case, the plant will show symptoms of dehydration: loose, curled leaves that gradually die back. If you notice these signs, don’t automatically water your plant; if it is already soaked, it will only make the problem worse!
A soggy plant can become dehydrated because when its roots are surrounded by water, it cannot absorb anything, not even water.
The solution
Water your azalea when the top few centimeters of compost are completely dry. Always check first with your finger or a moisture meter and never water your plant if it doesn’t need it. Never water on a schedule, as a plant’s needs vary by season and situation.
Should you be worried about Azalea turning red?
In short, it depends. If some of the older leaves on your plant turn red before they drop, that’s perfectly normal. However, if your plant’s new growth is red or if all of the plant’s leaves are turning red, it’s a sign that something needs to change in your plant’s environment or the way you care for it.