Alocasia is a lush beauty of a houseplant, prized for its showy stingray-like leaves. Alocasias are generally trouble-free plants, but they are not immune to common problems.
If your alocasia leaves are turning brown, I’ll help you probe the cause and show you how to get your plant back to robust health.
The most common culprit for alocasia turning brown is leaf scorch. This may be due to sunburn, fertilizer burn, root rot, or overwatering. Other common causes of alocasia brown leaves include diseases, pest infestation, low humidity, nutritional deficiency, and poor air circulation.
I’ll dive into each of these issues to figure out the underlying cause of browning in your alocasia plant. You’ll learn how to fix each problem, as well.
Causes of Alocasia Turning Brown
When healthy, alocasias boast large, dramatic dark-green leaves with zebra-like veining. They’re native to tropical and semitropical regions of Asia-Pacific. Think the Philippines, so they are happier in humid climates.
BUT you may not be able to transform your home into a tropical oasis. And that’s when problems creep in. One common issue is browning on alocasia leaves.
Could the culprit be a disease? Poor watering habits? Or, perhaps exposure to extreme temperature changes?
First things first, don’t panic. You can identify the problem by inspecting your alocasia. Look ahead for how to remedy each potential cause.
Alocasia loves to dry out a bit but is not completed before the next watering. In fact, it thrives in moist soils, but overwatering is a big no. Water-logged soil is a recipe for root rot, particularly if the potting mix is poorly drained.
Root rot hinders the healthy absorption of oxygen. Sickly roots, in turn, affect other parts, including the leaves which then turn brown.
Look for the following hints that overwatering may be the cause of alocasia browning:
- Yellowing or wilting leaves: Affects lower leaves first. Buy may spread quickly to other parts despite wet soil.
- Curling leaves: It’s a survival tactic due to sickly roots.
- Tipping: The tips of the leaves turn brown first due to root rot.
- A foul smell emanating from potting soil: A telltale sign of root rot.
How to Fix
You must treat the fungal infection immediately, as it spreads quickly. I’ve used the following steps to successfully treat alocasia browning due to overwatering:
- Pop out your alocasia from the container and check it for signs of root rot.
- Diseased roots are usually mushy, fragile, and brown or black. They may give off an offensive smell. Get rid of rotten roots using a sterile pair of scissors/pruners.
- Remove soil around the healthy roots. Wash off the rest with water.
- Dip the healthy root system in an anti-fungal solution. If you prefer organic methods, sprinkle them with ground cinnamon. Or dip roots in hydrogen peroxide solution.
- Repot your alocasia using a fresh, well-drained potting mix. Ensure the container is large enough.
- Park your alocasia in a well-lit indirect light.
Brown leaves on alocasia could be indicative of a bacterial, parasitic, or fungal disease. Bacterial leaf spots are typically fewer yet larger with a wet appearance.
Fungal diseases often start as small brown spots. If left untreated, they’ll blossom progressively and bleed into each other. You’ll then mistake them for a large blotch.
Keep an eye out for the following diseases that cause alocasia leaves to turn brown:
- Pythium rot – This parasitic disease affects alocasia severely and suddenly. Pythium rot begins as small circular spots (roughly 2-5 cm). They can expand rapidly, reaching up to 15 cm in diameter.
- Phyllosticta leaf spot – Early signs include small oval or circular spots. They will expand, and if many, spots will merge. Spots may start as gray or beige then turn brown/black. In either case, they may cave in, leaving scruffy holes in the leaves.
- Xanthomonas – The bacterial leaf rot appears first as small dark-brown spots. In later stages, they become necrotic, brown, and merge into irregular blotches.
- Anthracnose – This is a cluster of fungal disease that either affects the leaves or the roots of your alocasia. They result in pale spots on the top side of the leaves and brown rust-like spots on the underside.
How to Fix
Treat promptly to improve chances of survival. The best treatment will vary depending on the actual disease. Generally, you should:
- Separate and quarantine diseased plants.
- Trim off diseased roots, leaves, and other parts.
- Avoid overhead watering. Water your alocasia at the base early in the morning. Ensure ample air circulation.
- Apply Bordeaux mixture, anti-fungal, anti-bacterial, or other antimicrobials as needed.
- Instead, you can spray your plant using neem oil, tea tree oil, or baking soda.
Rust Spots on Alocasia Leaves
Rust spots are a fungal infection that invaded alocasia and a plethora of other indoor plants. It’s especially invasive in warm, humid conditions. Poor light can also be responsible.
Early on, rust spots are small brown or red rust-like spots on the leaves’ underside. They can be orange. A sudden spell of warmth can fuel rapid expansion. The spots will turn into large, ragged pustules.
If left untreated, the brown leaves will drop in. Although rarely more than a cosmetic issue, the leaves may eventually wilt and die.
How to Fix
Rust spots on alocasia leaves thrive in a warm, moist environment. So, you should:
- Make sure the leaves are as dry as possible. Avoid overhead watering. Instead, opt for drip irrigation, base watering, or use a soaker hose.
- If possible, water only in the early morning hours.
- Get rid of decaying, diseased, or dead plant matter.
- Spray with copper-based fungicides, neem oil, or baking soda.
Alocasias are happier in wet soils, but there can be too much of a good thing. Overwatered alocasia plants sometimes take in too much water. The cells will become too engorged with water that they rupture.
It’s often manifested as watery blisters or bumps on the underside of the leaves. The blisters will eventually dry out and leave tan or brown corky spots. Other signs of edema include drooping, lifeless, or shriveled leaves.
How to Fix
Oedema isn’t an infection or disease. That’s why the best course of action is to zero in on the cause and rectify it accordingly. I’ve found the following tactics to help revive edema-affected alocasias:
- Adjust watering habits. I prefer morning watering or regulated drip irrigation. Avoid warm water because it’s absorbed faster.
- Aeration is important. Make sure there’s ample distance between plants.
- Crank up the light intensity but stave off direct sunlight. This will help rev up transpiration.
Pest infestation is another leading culprit for leaf browning in alocasia. Insects like mealybugs can be particularly invasive. They can cause severe damage to the leaves and leave a raft of browning areas on the leaves.
Note that mealybugs and other pests in the family attack everything, from roots to stems and foliage. However, other insects focus on leaves. These include aphids, leafhoppers, scales, spider mites, and true bugs.
In that case, their bites will leave stripling and damage symptoms on leaves. Leaves may also turn brown along the veins and edges.
How to Fix
Use the following methods to fix a pest infestation:
- Take your plant to the bath or shower.
- Blast it with water to get rid of bugs.
- Spray with insecticidal soap, horticultural oils, or other insecticides like neem oil. Repeat weekly until you eliminate the bugs.
Alocasia does well in a medium to bright indirect light. Exposure to excessive heat, direct sunlight, or high temperatures can cause tissue damage. The damaged areas often transform into brown blisters.
Also, sunburns can develop if you rush your alocasia from a dark area to a brightly lit spot. Excessive sunlight can also trigger an influx of destructive free radicals. If the situation is not corrected, they’ll cause leaves to appear scorched, bleached, and then brown.
Drooping, curling, or wrinkling in the leaves is also a telltale sign of sunburns. Aside from the browning of leaf tips, you notice some leaf yellowing and paling.
How to Fix
- Remove your alocasia from direct sunlight promptly. In most cases, this means relocating your plant from a west-facing window to an east-facing one.
- Steer clear of heat drafts. Take your plant away from the heating unit, HVAC vents, or it might be exposed to too much heat.
- Sunburn damage is typically irreversible. Remove heavily damaged plant materials to prevent rotting and infections.
Alocasia plants are the happiest in well-lit places like window sills with east-facing exposure. They love mid to bright indirect sunlight. That’s because the plant is finicky about low light.
Weak artificial lighting, dark rooms, or poorly-lit places will not sustain healthy growth. Low light doesn’t cause browning of alocasia leaves directly.
The slow growth increases the risk for root rot, nutrient deficiency, overwatering, and edema. Therefore, these problems will cause the leaves to turn brown.
How to Fix
- Find a well-lit spot that receives indirect sunlight for your alocasia.
- You can use a top-notch light meter app. They’re dime a dozen on App Store and Google Play.
- If nutrition deficiency has set in, fertilize your plant accordingly. The same is true for overwatering, root rot, and edema.
Alocasia plants are built to flourish in temperatures ranging between 60ºF (15ºC) and 82ºF (28ºC). However, you want to maintain temperatures in the middle of this range.
Alocasias are especially vulnerable to temperature stresses, both cold and hot drafts. They not only shock your plant but may also cause tissue damage. The result isn’t pretty: brown color, curls, and dropping leaves.
Other signs of temperature stress on alocasia include:
- Presence of pale, tan, or yellow leaves.
- Browning of leaf tips.
- Sulky leaves that may wilt and fall over.
- Extra dry soil mix.
How to Fix
- Inspect the surrounding of your alocasia. Is there a hot or cold draft?
- Move your plant away from cooling vents, heaters, and leaky windows.
- Maintain temperatures in the lower 60’s at night and push it to around the mid-’70s during the daytime.
Alocasia is a sub-tropical and tropical plant. In layman’s terms, it’s built to thrive in warm, humid conditions. If the humidity is too low, the plant will dry out, and discolor areas will appear on the leaves.
In fact, brown tips and along veins are a surefire sign of low humidity. This is mostly true during winter when there’s too little moisture in the crisp air. Having a convection heating system can exacerbate the situation.
Too much humidity can have the same adverse effects. It creates a conducive environment for fungal diseases, edema, and root rot. All of these may result in leaf browning.
How to Fix
- If your living space is dry, give your alocasia daily misting.
- You can spray your plant gently every month or so during summer with the garden hose.
- During winter, set your alocasia in a humid room, like the bathroom.
- Water well, ensure good air circulation, and group non-diseased plant together to boost humidity levels.
- Use a water tray with pebbles to create a humid microclimate around your alocasia.
If your alocasia leaves have turned brown or yellow, frostbite could be the culprit. Again, this is a tropical plant that prefers warmer conditions. In fact, it does particularly well in the mid-temperature range between 60ºF (15ºC) and 82ºF (28ºC).
Alocasias don’t tolerate frostbites. When temperatures dip below 55ºF (13ºC), the cells will hibernate and eventually denature if they drop even lower. Frostbites also shock the plant and cause cell/tissue damage. In the end, the damage will appear as bumpy brown spots.
How to Fix
- Keep your alocasia away from cold drafts, such as unsealed windows.
- Make sure they’re in a temperature-controlled room. You may want to skip conservatories and patios during winter unless they’re heated.
- Ensure temperatures stay on the warmer side – i.e. between 60ºF (15ºC) and 82ºF (28ºC).
Lack of Nutrition
Ideally, alocasia should be fertilized once monthly from early spring through late summer. Depending on where you live, you can fertilize deep into fall. If you don’t, leaves will turn because of a lack of nutrition.
The most commonly deficient nutrients are nitrogen, iron, zinc, and magnesium. In all four cases, the leaves can turn anywhere from yellow to brown/black. Other signs of a lack of nutrition include stunted growth, necrosis, mottling, and chlorosis.
How to Fix
- If the yellowing is dominant over browning, nitrogen or sulfur can be deficient. Ensure that your plant is parked in a bright, but indirect light. Use nitrogen-rich houseplant fertilizer.
- Most nutrient deficiencies can be solved by using a fresh organic potting mix.
- Make sure to fertilize every month from early spring to fall. Follow dilution and administration instructions given.
Browning alocasia leaves can be a sign of the accumulation of fertilizer salts. This chemical buildup can result from the use of softened (tap) water or excessive fertilization over time. If you don’t add enough water, this will become even worse.
That’s one reason it’s a good idea to repot with fresh soil every couple of years. Softened water can also turn the leaf tips brown, so consider using distilled or filtered water to keep your plants happy.
How to Fix
- Drain excess fertilizer salt from the potting mix.
- Consider using a water filtration system or distilled water.
- Apply fertilizer sparingly, only once per month spring-fall.
More often than not, browning alocasia leaves are an indication of underwatering. It needs a consistent supply of moisture to thrive. If left dry for long, underwatered alocasia will wither, fall over, wrinkle in leaves, and die.
The surefire way to know if underwatering is the cause is to check the potting mix. If it’s too dry (2-4” of topsoil), the plant is definitely dehydrated.
How to Fix
- The best treatment is to provide your alocasia with enough water.
- Watering once early in the morning is advisable.
- Don’t overwater your plant; this will do more harm than good.
- Make sure the 2 inches of topsoil has dried a bit before the next irrigation.
How to Prevent Browning of Alocasia Leaves?
Knowing potential culprits for browning in alocasia is half the battle. The next half is doing what it takes to keep them at bay.
- Make sure the top 1-2 inches of potting soil had dried out a bit before watering.
- Water your alocasia only once in the morning. Or, as needed in hotter weather.
- Inspect the roots regularly for signs of root rot.
- Ensure good air circulation and separate your houseplant to prevent the spread.
- Use drip irrigation or water at the base of the plant.
- Avoid overhead watering.
- Removed infected plant material immediately.
- Avoid overfertilization by applying fertilizer once per month from early spring through fall.
- Repot with fresh soil mix every 1-2 years.
- Avoid tap or softened water that may aggravate salt buildup.
- Protect your alocasia from exposure to cold drafts.
- Never place your plant where temperatures fall below 55ºF (13ºC).
- Don’t let your alocasia touch windows.
- Set indoor plants to create a warm microclimate.
- Maintain humidity above 60%, but preferably around 70%.
- Mist your alocasia daily during winter and low humidity weather.
- Use pebble-filled water trays to improve humidity.
- Huddle your houseplants together to create a humid microclimate.
- Get a humidifier.
- Keep your alocasia from direct sunlight.
- Avoid low light positions, as well. Sudden relocation may cause sunburns.
- Fertilize once every 3 months with potassium and calcium nitrate to strengthen cell walls.
- Avoid overwatering, especially during winter.
- Don’t use warm water for watering.
Rust Spots on Alocasia Leaves
- Make sure your alocasia is well-aerated.
- Create a distance between your houseplants.
- Quarantine affected plants immediately.
- Move your alocasia close to a window sill.
- Expose to bright yet indirect light.
- Use sunlight apps to measure the intensity.
- Inspect your alocasia routinely for pests, especially the back of the leaves.
- Use clean containers and potting mix.
- Don’t let the leaves of different plants touch each other.
- Bright (indirect) light, adequate watering, and proper air circulation should prevent most insect pests from invading your spider plants.
- Don’t place your alocasia close to air, heat, or cold vents.
- Avoid direct sunlight.
- Keep indoor temperatures uniform between 65°F (18°C) and 85°F (29°C).
The most common causes of browning in alocasia are disease, rust spots, overwatering, fertilization burn, and low humidity. You can revive your plant by remedying the issue.
Good aeration, proper watering habits, optimal temperature, bright/indirect light, and ideal humidity should prevent most of these predicaments.