Why Anthurium Leaves Have Brown Spots (What to do About It)

What’s more beautiful than anthurium plants? From pink to purple and white, the colors of these lovely flowers are endless. While the blooms are eye-catching, giving your home a refreshing vibe and charming look, seeing brown spots on the leaves is worrisome.

Your anthurium leaves turning brown indicates that you should change your care routine. Sometimes, brown leaves aren’t a big deal; just a simple fix, and your plant will be fine in no time. However, you’re better off knowing what causes brown leaves and how to prevent or control them. With this information, you can give your anthurium the care it needs to thrive.

Keep reading for everything you need to know why anthurium leaves have brown leaves and what to do about them.

Causes of Brown Leaves on Anthurium Plants & How to Fix It

From watering issues to lighting and the environment, these factors play a part in leaf browning. Besides brown leaves, these factors may also result in drying and wilting. Once you’ve identified the cause of brown leaves, you can take measurable steps to manage it and prevent further damage. 

Excess Direct Sunlight

Typically, anthuriums thrive best in the shade. The flamingo plant grows optimally under 60% sunlight or 1,800 to 2,500-foot candles. Excess direct sunlight is a major cause of brown leaves, leading to wilting and death of plants if left untreated. Meanwhile, too little sunlight can impede plant growth, limit photosynthesis, and reduce sprouting. Exposing anthurium to the scorching sun gives undesirable results, with the upper leaves becoming the most affected. 

To fix lighting problems, move your plant to a less shady spot or use a translucent curtain to prevent bright light from reaching the plant. If you don’t know where to place your anthurium, a light meter app may come in handy. Download the app on your smartphone and use your phone’s camera to take a reading of the light levels in your home. 

This reading helps to locate the right spot to place your plant and keep track of changes in light intensity. Ensure you don’t prune damaged foliage after moving the plant to a suitable place. Allow your plant to adapt to the new conditions, producing new leaves before pruning the brown leaves.

Overwatering

Another thing that contributes to leaf discoloration is overwatering. Gardeners are likely to overwater their houseplants if they don’t strictly follow the watering schedule. Besides water being a primary cause of this issue, planting in poorly aerated soil, growing plants in large pots, and using a pot with few drainage holes play huge roles. 

Anthurium leaf tips become brown when roots don’t supply adequate water and nutrients. Root rot may likely occur due to overwatering, brown leaf tips, and yellowing of lower leaves. Black, soft, slimy roots indicate root rot. 

Once you notice the plant’s growth deteriorating, remove it from the container or pot and check the level of damage. Remove rotten roots using sterile pruners or scissors. Gently remove plants from the soil and wash off soil residue. Then, repot anthurium using a fresh potting mix and tamp it down. Ensure you properly care for the anthurium.

Over-fertilizing

Aside from overwatering, over-fertilizing is another culprit of browning anthurium leaves. Generally, anthuriums require nitrogen, phosphorus, and potassium for growth and development. Lack of these nutrients can result in brown leaves on anthuriums. These leaves have yellow edges and brown spots without any diseased droplets. 

Furthermore, nutrient-deficient plants have reduced growth, with younger foliage smaller than the matured ones. In this case, the new leaves become light and deformed instead of having a glossy green hue. In a bid to improve nutrients in soil, many gardeners over-fertilize plants. Unfortunately, over-fertilizing also causes brown leaf spotting and white/brown crusts on topsoil. 

Consider flushing the soil with enough water to dissolve excess salt to correct the defects. You might want to pause fertilization for about 6 months till your plant produces new and healthy foliage. You can consider repotting in a fresh soil mix if the salt buildup is excess. Though this process may be strenuous and time-consuming, it’s worthwhile if that’s the only way to save a badly affected plant. 

Ideally, many gardening enthusiasts use a controlled-release fertilizer, but in situations where leaves turn brown, liquid fertilizer will be a better option. Apply the fertilizer to the plant for a few weeks until it fully recovers. Usually, your anthurium requires a small amount of fertilizer to thrive, so avoid applying it in excess. Before adding to the plant, ensure you dilute the fertilizer to ¼ of the recommended strength. 

Experts discourage fertilizing plants during the winter. Also, fertilize sparingly during the growing season. Using organic fertilizer may be an effective way to reduce over-fertilizing. You might not need to use supplemental fertilizer for about 2 years when you use fertilizers with 10% compost or worm castings.

Acclimation

Compared to other causes of brown leaves, acclimation has fewer effects on anthuriums. Usually, these plants grow best under controlled conditions; however, you might be unable to control lighting, humidity, and temperature when grown indoors. As a result, anthuriums can develop brown spots on their leaves. 

To help plants adapt to home conditions:

  1. Ensure you purchase it from a reputable seller who properly tends to the anthurium.
  2. Buy newly stocked anthuriums from large stores, reducing the dormancy period. If buying anthurium online, ensure the plant isn’t subjected to cold stress before delivery.
  3. Check that light, temperature, and humidity levels are suitable for plant growth and survival.

Pests

Pest infestations are another contributing factor to brown leaves in anthuriums. Mealy bugs, white flies, aphids, thrips, and spider mites are capable of causing systemic damage and leaf discoloration. You may have difficulty identifying pest attacks as they exhibit similar symptoms to overwatering and underwatering. 

Check both sides of the leaves, stems, and soil for pest presence. You can easily spot thrips, mealy bugs, and aphids when you look closely at hiding holes or affected areas. However, identifying spider mite attacks may seem difficult.

Meanwhile, you can easily locate the affected regions if it’s an infestation. Once you pinpoint an infestation, isolate the affected plant as soon as possible to prevent its spread. Also, handpick pests or use a hoe, showerhead, or tap to wash off bugs from leaves. Every week, use neem oil, horticultural oil, or isopropyl alcohol to kill insect pests on plants. 

Consider isolating new plants for about two weeks before introducing them to your houseplant collection.

Cold Stress

As tropical plants, anthuriums grow best under temperatures ranging between 59-86°F. Temperatures below this range result in cold stress, causing brown leaves and foliage damage in anthuriums. The damage exhibits first as patchy yellow spots that become brown, spreading to other parts of the leaves. 

When anthurium is exposed to low temperatures for prolonged periods, leaf browning worsens if not managed. Leaving plants in a drafty or cold room during winter or close to a cold air conditioning vent can cause cold stress. To manage this issue, you’ll need to monitor the temperature your anthurium is exposed to. 

Humidity

Low humidity plays a crucial role in leaf browning on anthurium. While the plant flourishes at about 60% humidity level, if it drops below 50%, its leaf tips will turn brown in no time. Like temperature, you’ll need to monitor humidity levels using a hygrometer. If humidity is below the optimum level, try placing a shallow dish of water beside or beneath the plant to promote evaporation, resulting in increased humidity. 

Another way to improve humidity levels is by grouping your plants, which accelerates the transpiration rate, creating a humid environment for your plant.

Furthermore, consider moving your anthurium to the kitchen or bathroom, where humidity levels are higher than in other rooms. Using an electric humidifier is probably the best way to raise humidity levels. 

A preferred choice will be one with a large water reservoir so you won’t go through the rigor of refilling the hygrometer regularly. However, a cheaper option is misting the plant using a spray bottle. But this is high maintenance as you’ll need to adhere strictly to some measures to prevent soggy soil.

Underwatering

Underwatering is one of the most likely causes of leaf browning in anthuriums. Old leaves are more prone to developing brown spots than young ones. They can become completely brown and fall off within a short while. Moreover, the blooms will develop brown spots around the leaf tips and edges. 

In addition, anthuriums can wilt fast once they’re underwatered. Underwatering is more prevalent in the summer because hot air increases the evaporation rate, and the anthurium is in its growing season. So, the need for more water. 

You can easily identify plants with low water content. The soil feels dry to the touch, and the pot will be light due to low moisture retention. Typically, you won’t always remember to water your anthurium, so it’s best to check the plant weekly. 

Regular checks will help nip any problem in the bud before it escalates. Water the plant immediately if the topsoil feels dry to the touch. Then, allow water to soak the soil before draining excess water through potholes. 

While you can easily correct underwatering, some factors predispose your anthurium to it. If the plant is rootbound, it can dry out quickly after watering. Repotting in a larger pot will likely solve this problem. The type of soil used for planting also determines its moisture retention level. A suitable soil medium should be well-drained and have increased water capacity. 

Planting anthurium using a potting mix that isn’t well-drained will make the plant dry out quickly, wilt, and have brown leaves. Is your anthurium receiving excess light and heat? These extremes can cause underwatering because excess light and heat make the plant lose water faster.

Age

Leaf browning is not usually due to inadequate care or exposure to incorrect conditions. Don’t forget; leaves don’t last forever. They’ll likely become brown after completing their life cycle. 

However, it is a natural process that shouldn’t be much of a concern to you. So long the plant is only losing a few leaves, especially old ones, it’s not an underlying problem. Depending on your preference, you may let them fall off by themselves or use pruning shears to remove them to allow new growth. 

Disease

Besides the leaf browning causes mentioned above, brown leaves are sometimes the signs and symptoms of a disease. When disease-causing agents like fungi and bacteria invade plants, they cause blotchy patches or irregular brown spots on leaves. 

Let’s consider some diseases that result in leaf browning. 

Leaf Blight

Also known as leaf spot, leaf blight is a common disease that affects anthuriums. The causative agent, Xanthomonas, a bacterium, enters the pores through the leaf margins. Bacteria can also gain entry through leaf tissues attacked by insects or damaged by pruning. 

The bacterial infection first appears as water-soaked yellow lesions that progress into brown spots along the leaf margins. Next, small sap or guttation droplets appear at night when the temperature is high and potting soil is warm and wet. The droplets contain amino acids, which serve as a food source for the bacteria. As bacteria multiply, the plant may not show symptoms until months after.

Meanwhile, these bacteria spread quickly throughout the plant, infecting adjacent plants. Over time, the leaves display a bronze appearance, with flowers fading in color and floral quality reducing. If the plant is left untreated, it wilts and dies. Besides bacteria entering leaves through pores and tissues, they can also be transmitted through wounds obtained by harvesting flowers. 

Furthermore, this disease agent spreads across wet surfaces, and that’s why wet foliage is prone to leaf blight. Due to its susceptibility to the disease, keeping anthurium dry is essential. Instead of full watering, you can practice drip irrigation by watering your plant using ice cubes. Place about 6 ice cubes on the soil and allow it to melt. Do this once per week to prevent waterlogging. 

If the disease manifests as systemic infection, you will have to destroy the whole plant to prevent the wide spread of the disease to other plants. The foliar infection affects only the leaves, meaning you can manage the condition since the infection hasn’t yet affected the vascular system. 

Removing and burning infected leaves is an excellent way to control leaf blight. Avoid using shears to prune plants. If you must use them, ensure it’s well-sterilized. When cutting infected leaves, break the petiole close to the leaf blade to remove them. Invariably, this curbs the spread of disease. 

Adopting preventive measures may be the best way to stop the occurrence of leaf blight. Providing adequate care to plants enables them to grow stronger and develop natural disease resistance. Some experts recommend treating leaf blight with copper fungicides, but studies have shown that Xanthomonas resist copper. In addition, adding these chemicals to plants can lead to phytotoxicity. 

Bacterial Wilt

Bacterial wilt is caused by Ralstonia solanacearum, a bacterium that thrives in high temperature and humid conditions. Leaf yellowing, also called chlorosis, is the first sign noticed on leaves. The disease spreads fast, affecting the plant’s vascular system, giving stems and veins in leaves a characteristic bronze color.

Cut stems of infected plants ooze brown slime when squeezed. In the later stages of the disease, the leaves will begin to droop and wilt. It also impedes physiological functions like flowering and growth. 

Generally, the disease-causing organism spreads in water, soil, by contact, and on tools. Introduce healthy, disease-free plants, making sure all growing mediums are sterilized. A more effective way to control the spread of disease is by adopting sanitary measures. Discard contaminated soil and plant material. If you want to reuse pots and trays used for infected plants, ensure you clean them thoroughly. 

Also, soak the items in disinfectant to eliminate other bacteria. Sterilize knives and clippers using a disinfectant containing ammonium compound or diluted bleach solution. 

Phytophthora/pythium

Phytophthora/pythium, also known as water molds, mainly target root systems. While the roots are the most affected, the pathogens infect other areas like the crown and stems of plants. A core symptom of the disease condition is root sloughing. 

As the disease progresses, the leaves may develop brown lesions. Phytophthora thrives in wet soil under temperatures ranging between 59°F and 74°F. To prevent phytophthora infection, use a light, well-drained potting mix for planting anthuriums. In addition, use disease-free stock plants and discard infected plants. 

Foliar Nematodes

Aphelenchoides fragariae, also known as strawberry foliar nematodes, is a small roundworm that infects young anthuriums. The infection causes thin stripes across leaf surfaces and brown spots around the veins. Eventually, the plant undergoes necrosis and dies. Severe infestation spreads rapidly, resulting in stunted growth and leaf browning. You’ll need to discard the whole infested plant to prevent the spread of disease to other young anthuriums.

Final Thoughts: Anthurium Leaves Turning Brown

Leaf browning can result from several factors like underwatering, waterlogged soil due to overwatering, low humidity, excess sunlight, pest infestations, and diseases. Identifying the actual cause of brown leaves in anthuriums will help you improve your care routine and save your plant.