Alocasias are popular houseplants recognized for their large glossy, arrow-shaped foliage. They are a little fussy with their needs, so they need conditions similar to their natural habitat. Otherwise, their leaves will start to turn brown.
In this article, we will learn why your Alocasia is turning brown and how you can get your plant back to health again.
Your Alocasia might be turning brown due to leaf burn, which can happen due to sunburn, poor water quality, or over-fertilization. Other causes of brown leaves include watering problems, pest infestation, fungal diseases, low humidity levels, and temperature stress.
Inspecting the plant and identifying the exact cause of brown leaves will help you fix the problem.
In this article, we will understand the issues to figure out the actual cause of brown leaves on your Alocasia plant. We will also find out the solution to each of these problems.
Table Of Contents
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Why my Alocasia leaves are turning brown?
A healthy Alocasia plant will have large dark green leaves with zebra veining on it.
These plants come from tropical and semi-tropical regions and are happiest when they receive warm temperatures and humid environments.
It is somehow tricky to transform your house into a similar climate.
And this is when the problems arrive.
Alocasias, when they do not receive a suitable growing environment, will show issues like the browning of leaves.
There can be several reasons for Alocasia brown leaves, such as poor watering habits, diseases, temperature changes, and many more.
Let us now discuss all the reasons behind brown leaves in detail.
A common reason behind brown leaves on Alocasia is overwatering.
If you overwater it for a prolonged period, the plant will show signs like brown leaves.
If the soil doesn’t dry between each watering, your plant will be at high risk of overwatering.
The excess moisture restricts airflow in the soil, due to which the roots cannot breathe properly and becomes weak.
Such roots will get trapped by diseases like root rot, which affects other healthy parts of the plant that leads to the development of brown leaves.
Generally, the plant’s lower leaves will turn yellow before turning brown.
If the plant has root rot, the tip of leaves will turn brown, and a foul odor will come from the soil.
How to fix overwatering?
- If your Alocasia is overwatered, you should stop watering it for a few days, leave it in a sunny spot, and wait until the soil recovers.
- If the soil mix is wet and the plant is not recovering, you should remove the Alocasia from the pot and check the roots to inspect whether they are healthy.
- If the roots are healthy, you can spread them on paper and let them dry in the sunlight. But if it is mushy and brown, you need to prune off the damaged roots with a pair of sterilized scissors.
- Dip the healthy roots system of the plant in an antiseptic fungicide.
- Then repot your Alocasia in a fresh soil mix and pot.
- Water the soil and keep the plant in a well-lit spot.
- Resume fertilizing once the plant recovers.
The leaves of your Alocasia can also turn brown if you are underwatering the plant.
Alocasia needs a consistent moisture level in the soil to thrive.
If the potting mix is too dry and has cracks, the plant is dehydrated.
If the Alocasia is left dry for a prolonged period, it will wither and become dry.
The leaves will turn brown due to a lack of enough moisture.
How to fix underwatering?
The best treatment for restoring moisture is providing the plant with enough water.
- Take a chopstick and poke some holes into the soil to aerate it. You should then thoroughly water the Alocasia until the excess water starts to drain out of the drainage holes under the pot.
- It is another method to fix under-watering. Here you need to take out the plant from the pot and place it in a container filled with water. Do not remove the plant until the soil soaks up that water and turns moist. Once the soil turns moist, remove the plant and place it in the pot and keep it in a dry place.
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Poor water quality
Brown spots on Alocasia leaves can occur when you water the plant with poor quality water.
Regular tap water usually contains minerals like chlorine, fluorine, and bicarbonates that harm the plant.
Therefore, the plants develop brown spots due to the harmful effects of these salts.
How to provide good quality water to Alocasia?
If you want your Alocasia not to get stressed due to poor quality water, use rainwater or filtered water.
If these are not available, let tap water sit overnight.
This reduces the mineral content to some extent, and you can then use this water to water your Alocasia.
The leaves of your Alocasia plant can turn brown due to fungal disease, parasites, or bacteria.
Fungal diseases can start as small brown leaf spots on the leaves.
Bacteria will cause few yet large spots with a wet appearance on leaf surfaces.
Here are the following diseases that will cause your Alocasia to turn brown:
- Pythium rot: This is a parasitic disease that causes small circular spots (2-3 cm) on leaves, and as they expand, the spot reaches up to 15 cm in size.
- Xanthomonas: This leaf spot is caused by bacteria that form small dark brown spots on leaf surfaces. Later, spots merge into thick blotches.
- Anthracnose: It is a cluster of fungal diseases that affects your plant’s leaves and roots system. They form pale or brown rust spots on leaves.
- Phyllosticta leaf spot: This leaf spot is caused by an asexual fungus that forms oval or circular brown spots on leaves. As they expand, the spot merges and often creates holes in the leaves.
How is alocasia plant disease treated?
- First, separate and isolate the diseased Alocasia from all other houseplants.
- Then prune off the diseased leaves and other infected parts of the plant.
- Spray your Alocasia with Neem oil or horticulture oil as needed.
- You can also use fungicide to treat the fungal diseases.
- You can also use antimicrobials to kill harmful micro-organisms.
- Water your plant only in the morning and avoid overhead watering.
Alocasia loves to be in moist soil but will suffer if you overwater them.
When you overwater your Alocasia, the roots take up more water than the leaves can transpire.
As s result, the cells in the leaves get engorged with water and form watery blisters on the underside of leaves.
This condition is known as Edema.
Later the watery blisters will dry out and leave brown spots on the leaves.
How to fix Edema?
- You should adjust your watering schedule. Water the Alocasia only when the top 2 inches of the soil feels dry to touch.
- Always allow the soil to dry out partially between each watering.
- Do not use warm water as it is absorbed faster in the soil. Use distilled water at normal room temperature.
Rust spots are fungal infections that infect the plant in warm and humid conditions.
Rust spots will appear as small brown spots on the underside of leaves.
If left untreated, the spot will turn into large pustules. Also, the infected leaves will wilt and die.
How to fix rust spots?
- Rust spots thrive in a warm, humid environment and so you should keep the leaves as dry as possible.
- Do not do overhead watering, instead of doing base watering or follow drop irrigation.
- I prefer watering the plant in the morning hours only.
- Prune all the infected, damaged leaves or dead matter of the plant.
Pests are another reason major reason for your Alocasia’s brown leaves.
Pests such as aphids, spider mites, scales, mealybugs can attack your plant.
The bug takes up nutrients and minerals from the plant and will cause severe damage to your plant.
Their bites will leave behind a raft of brown areas on the leaves.
How to treat a pest-infested Alocasia plant?
- First, isolate your plant from other houseplants to prevent pests from spreading to them.
- If pests are visible, you can handpick them from the plant.
- You can shower the plant to remove the pests from the plant.
- You can use Neem oil solution and spray it all over the plant to remove pests.
- You can dip cotton balls in rubbing alcohol and wipe the infected areas of the leaves.
- Prune off all the infected stems and leaves using a pair of sharp scissors.
Alocasias will be happiest when grown in a well-lit area such as window sills or other places where they receive bright, indirect light.
They will not grow healthy if you keep them in the dark or poorly lit places.
Poor light will cause the leaves to turn brown directly.
Lack of light will increase the risk of overwatering, root rot, and nutrient deficiency.
All these problems will cause the browning of alocasia leaves.
How to fix the poor lighting problem?
- Choose a well-lit spot that will support bright, indirect light for Alocasia. The best place to keep your plant will be the East or North-facing window.
- If the plant is lacking nutrition, fertilize your plant enough. Similarly, fix other problems like overwatering or root rot.
Alocasia prefers to grow in medium to bright indirect light.
Exposing them to direct sunlight or excessive heat can result in tissue damage.
The damaged areas will later turn into brown spots.
The plant will also get sunburn if it changes from a dark place to a brightly lit area.
The direct rays from the sun can damage the cells causing the leaves to appear scorched, curled, and brown.
How to fix a sunburned Alocasia plant?
- First, you should remove your Alocasia from a spot with direct sunlight and relocate it to a spot where it doesn’t receive bright light.
- Keep the Alocasia away from any source of hot drafts. Do not keep it near any heating device, heating vents, etc.
- Sunburns are irreversible, so you should prune off the burnt leaves.
Alocasias come from tropical and subtropical regions that are warm and humid.
So, they prefer a temperature range between 65-85 degrees.
They are vulnerable to both hot drafts and cold drafts.
Any of these will stress the plant and can cause tissue damage.
Eventually, the leaves of your plant will turn brown, curl, and will fall off.
How to save Alocasia from temperature stress?
- First of all, inspect the surrounding region of your Alocasia plant. Try to find whether it’s a hot or a cold draft affecting your plant.
- In any of these cases, keep the plant away from frosty windows, cooling vents, leaky windows, or heaters.
- Try to maintain temperatures around mid 70 degrees during the daytime and mid 60 degrees at nighttime. You can also use a thermostat device to set temperatures for your plant.
Alocasia, a tropical plant, will need humid conditions to grow.
If the humidity level is low, the plant will transpire at an increasing rate, due to which it will dry out faster, and discolored areas will be visible on the leaves.
Brown tips are mostly seen in winters when there is very little moisture in the surrounding.
Also, the plant will dry out faster if you place them near any heating system.
The dry air from such a device will cause dehydration in the plant, due to which their leaves will wilt and turn brown.
How to raise humidity for an alocasia plant?
- You can mist the leaves of your plant twice or thrice a week.
- You can increase the humidity around your plant by using a humidifier device.
- You can group your Alocasia plant with another humid-loving houseplant.
- You can place your plant in trays filled with pebble and water to build a humid microclimate around it.
Alocasias are heavy feeders and should get fertilized every month during their growing season.
Lack of nutrition will make them weak and unhealthy and cause their leaves to turn brown.
They need vital nutrients such as Nitrogen, Phosphorous, Potassium, Iron, and Zinc for growth.
Lack of these nutrients will cause the leaves to turn anywhere from yellow to brown.
How to fix an underfertilized alocasia plant?
- If the yellowing is more prominent than browning in leaves, it indicates your plant is in a deficit of nitrogen and sulfur. You should provide your plant with a nitrogen-rich fertilizer.
- You can feed your plant with liquid fertilizers in NPK ratio 20:20:20 once a month in the spring and summer seasons.
- You can solve these nutrient deficiencies by using a fresh organic potting mix rich in minerals and nutrients.
Brown leaves of Alocasia can be a sign of excess fertilizer salts if you are over-fertilizing your plant.
The accumulation of salts can result from the excess use of tap water or over-fertilization.
Fertilizing the plant during winters will increase the risk of over-fertilization as they do not require fertilizers during this season.
The excess salts in the fertilizers will burn your plant’s roots and cause their leaves to turn dry, brown, and crisp.
If you think that the brown leaves are due to over-fertilization, check the soil for any salt build-up.
The excess salt can accumulate over the soil or the base of the plant and can be seen as white crystals.
How to fix an overfertilized alocasia plant?
- You should cut off all the damaged leaves and stem that you can see on your plant.
- You can scrap the top few inches of the soil to eliminate excess fertilizers formed on it.
- Wash the plant with a strong stream of water so the excess fertilizers will drain off along with the water.
- Water the plant with distilled water and avoid using tap water.
- Avoid fertilizing the plant for a few months and resume fertilizing once the plant shows growth.
How do I prevent brown leaves on my Alocasia plant?
I have discussed the possible reasons for brown leaves on your Alocasia in this article.
Now we will understand how to prevent brown leaves on them.
Here are some care tips are given below to encourage healthy growth and prevent brown leaves on your Alocasia.
- Keep your plant in a location that provides bright, indirect light and keep it away from direct sunlight.
- Water your alocasia plant only when 25-50% of the soil has dried out before watering. Avoid watering without checking the soil.
- Avoid using tap water and distilled or filtered water to water your plant.
- Ensure good air circulation around the plant.
- Fertilize your Alocasia with a balanced 20:20:20 NPK liquid fertilizer once per month during the spring and summer seasons. Avoid fertilizing the plant during the winter months.
- Repot the plant with fresh soil every 1 to 2 years.
- Try to maintain a minimum 40-50 % humidity level for your pant.
- Use a pebble tray or humidifier to improve humidity around your plant.
- Keep your plant away from leaky windows, heat, or cold vents.
- Inspect your Alocasia daily for pests and check the undersides of the leaves.
- Spray your Alocasia with a Neem oil or horticulture oil every month to keep pests away.
- Prune off the damaged, infected leaves and parts to keep your Alocasia away from stress and encourage new growth.
Reference: Science Direct, Propagation of Alocasia, The University of Arkansas Division of Agriculture, Alocasia sanderiana, Alocasia micholitziana.