As a native plant to the tropical rainforests, Alocasia macrorrhiza spread in South East, Pacific Islands, and Australia. The first noticeable things about this plant is its gigantic size as a whole. It has been used for years as a staple food. In modern times it is famous as a decorative plant.
Alocasia macrorrhiza is a species included in Araceae family thanks to George Don in 1839. Its other name are Giant Taro, Bira, Elephant Ears, Pia, etc. It is rumored that this plant is the one appearing in the famous fairytale “Jack and the Beanstalk”. It has distinctive features as follows.
First of all, remember that the leaves of Alocasia macrorrhiza point upward while Colocasia point toward the ground. Its arrow-shaped leaves have green solid color in most season and glossy touch. Since each leaf may reach 3 to 4’ feet wide and 3-6’ feet long, many said it resembles the “elephant’s ears”.
On the surface there are small bumps covered with wax. These bumps help reduce the contact of water from above (in case of heavy rain) and slowly flow the water droplet fall from the leaves while gather the dirt on it. Rigid and tall stalks support the leaves of Alocasia macrorrhiza.
Rarely Bloomed Flower
In contrast to the leaves and stem, the flower size is relatively small. It is hard to spot the flower as it grows seasonally on spring or early summer. Many said that Calla lily is the closer example to describe this flower. It consists of spathe and spadix in the combination of green, yellow, and white color.
Sadly, not all Alocasia macrorrhiza will bloom the flower especially when you grow it indoor. The lucky ones can enjoy the bloomed flower only for five days. You can only smell its fragrant when you get closer as it has a weak scent.
Alocasia Macrorrhiza Care Guide
Planting and growing Alocasia macrorrhiza might be a hassle, but there are various kind of Alocasia in different size and color to choose from. It is relatively easy to take care of this plant, but some cautions exist as this plant has specific characteristics.
Adjusting Light and Temperature
The best condition to grow is warm and damp environment. A favorable climate will be a location under USDA hardiness zones 9b to 12. Air conditioners, heaters, and windy area are bad variables for growing this plant. A stable condition is a good balance between the light, humidity, and air circulation.
- If you grow it indoor, pick a spot near a window facing east, south, and north. Use illuminated windows to filter the excessive sunlight from the outside. When such spot doesn’t exist, consider using fluorescent lighting placed overhead to provide enough sunlight. Rotate it regularly to ensure that each part of the plant has enough light. Indoor temperatures should be ranging between 15°C – 24°C.
- If you choose to plant it outdoor, the exposure to the full light is permissible for 2 hours every day and longer than that will result in discoloration. The canopies of trees (preferably tropical species) around Alocasia macrorrhiza will help blocking the direct sunlight and creating an ideal humidity. When the weather gets cold especially below 10°C, bring it inside, and equip it with pebble tray or humidifier.
The key for watering Alocasia macrorrhiza is to keep it slightly moist. A room temperature/lukewarm water and distilled water are the best options for indoor setting. Natural rainwater is a gift when it comes to outdoor setting. Pour the water slowly in circular motion evenly. Wait until the top soil (around 3 cm or 1/3 of it) dry, then continue pouring the water.
During spring and summer avoid under watering. Give less water during winter as the plant hibernates in this period. Once or twice a week is the approximate frequency for watering while waiting for the leaves to dry. Watering at night is not advisable.
Put your finger inside the soil at least an inch for a simple check. If your finger feels wet and much soil stick on it, don’t give water to the plant yet. Repeat the same action until a reverse result appears.
After watering the plant, apply houseplant fertilizer in allowed ratio. Give the plant fertilizer every 2 weeks in spring or summer seasons (critical months/growing period season) and monthly during winter. In order to prevent the burn, it is preferable to feed it after watering. You can adjust the frequency as you need after observing the plant’s growth.
Alocasia Macrorrhiza Soil Mixture
The soil for Alocasia macrorrhiza should fulfill the following characteristics:
- has a lot of organic matter,
- able to provide high humidity,
- able to let the water drains well.
A mix of common potting soil, fresh compost, peat moss, as well as perlite is an excellent combination for this plant.
The average ph level should be around 5.7 to 6.3 (slightly acidic and neutral). Adding coarse sand or gravel is another great idea as it works as a buffer zone when it comes to standing water. The wrong soil composition will cause root rot and soil-borne diseases.
Regular grooming and pruning are necessary to maintain and control the plant size and spread. The longer you leave it as it is, the harder for you to trim the dying leaves, stems, or roots. Always use sterile tools such as shears, cutter, or knife to prevent bacterial and fungal diseases.
When trimming, make a clean cut as not to shock the plant. Too much wound or heavily damaged part will weaken its growth and lower its health quality. Do not hesitate to cut down all the leaves parts down to its base if necessary. Naturally, the crown will regenerate a new batch of stem and leaf. Clean the plant debris spread around the plant, soil, and pot.
Read also : Alocasia Wentii – Ultimate Care Guide
Repotting Alocasia Macrorrhiza
As this plant is a heavy feeder and it grows rapidly, it requires repotting every 1, 2, or 3 years.
When to repot
There are simple ways to confirm when your plant needs repotting. Some noticeable signs are the roots popping on the soil surface/outside the pot, white salt crystals formed on the soil surface, and the leaves wilt when watering for several times.
How to repot
Whatever kind of pot you use for repotting, select one with drainage holes at the base. The pot size should be at least 2 cm larger or one size larger than the old one. In the spring, repot your plant within a day after watering for fast recovery. The steps are simple: remove the whole plant, prepare fresh and good soil mix, plant it deeply, and then water the plant.
Due to its size, repotting can be an overwhelming work for some people. And some enthusiast like to divide the rhizome. In any case, make a good preparation for repotting. For instance you can ask help from friends or family, specifically when you need to take the whole plant from its pot.
One of the purpose of propagation is to maintain a manageable size of the plant. The prime period to complete this task is between springs to early summer time. Stem cuttings is only possible if your plant is mature enough. You will have to wait longer to see the mature plant when using seed method. If you want to have more plants quickly, these two methods are not for you.
So far, basal offset division is the most effective way for Alocasia macrorrhiza propagation compare to stem cutting or seed method. Other names of basal offset is root or rhizome division.
- A good preparation is the basic. At initial stage, you need to water your Alocasia macrorrhiza then leave it for a day before propagation. A good basal candidate should come from a healthy root system plus having three leaves at minimum.
- Next, take the whole plant from the pot and clean the soil around for better access. Separate the offset, leaves, root system, and stems carefully. After you divide the offset, put each into a new pot with organic compost. When it is hard to tug the plant, it means the root has established itself well. It usually occurs after a few weeks of propagation if you take care of it properly in the early stage.
Alocasia Macrorrhiza Varieties
This plant comes with several varieties, here are some of them :
- Variegated Alocasia Macrorrhiza : This variety has white splash around the leaf, make it perfect for decoration.
- Alocasia Macrorrhiza New Guinea Gold : Considered rare by some, this variety has gold sparks around the leaves.
- Alocasia Macrorrhiza Stingray : Why does it named stingray? That’s because of the shape of the leaves formed just like a stingray.
Usage of Alocasia macrorrhiza Around the World
- As one of the source of carbohydrate, Asian people consider Alocasia macrorrhiza as potato replacement and a common food served on the table. They often use stems and root as staple food. When the corm is sufficiently cooked, it resulted in a high level of starch, used as energy in the body. People also locally produced this plant by turning it into crispy chips.
You must peel and boil the root and stem well before consumption. In this way, the high concentrations of calcium oxalate contained in the plant will be completely broken down. Eating them raw will cause skin burn and unpleasant pain in the mouth. Decorative plants that is usually bred from its original version aren’t edible.
- As ornamental plant, this plant help creating a tropical ambiance in the surrounding area. You can planted it indoor, patios, or inside the green house. It can be used an eye-catching plant in a room. When planted outdoor, it also works as a good shade.
- Another unique example of Alocasia macrorrhiza usage comes from two different areas. There are times when the Pacific Islanders use the leaves as temporary umbrellas when raining. In Taiwan, people use the tuber parts for medicinal purposes. They pounded it well to soothe and cure swollen body parts.
Dealing with Pest
Spider mites is one of the largest enemy of Alocasia macrorrhiza aside from mealybugs and aphids. Most pests are looking for the plant sap. As soon as you notice the pest, separate the plant far from others. The fastest way to get rid of the pest is by using a reliable insecticide that kill the pest along with their eggs.
To prevent the pest from attacking your plant, maintain the plant hygiene by frequently cleaning it from dust and debris. Spraying or wiping the plant using neem oil, mild soapy water, or alcohol can remove the dust easily. Keeping the humidity in the high level will also effectively prevent spider mites. Check all parts of the plant regularly since pests usually hide in the unseen spot.
Handling Common Diseases
Basically, damp environment is the cause of diseases in Alocasia macrorrhiza. This could be the result of wrong watering and bad air circulation. The symptoms that often appear are dark or brown lesions and spots on the leaves. Several common diseases associated with Alocasia in general are described below.
When the leaf surface has different color other than green (usually yellow leaves or dark spot), you plant might be infected with crown rot disease. From the soil, the disease spread to other parts of the plant. After experiencing discoloration, the plant will start to lose its tissue strength and rot. If not being treated soon, it will wilt then die. For younger plant, pay more attention because it has a harder time to fight this diseases than the mature plant.
Fungal leaf blight
Fungus as the main perpetrator here cause lesions on the leaf surface. These lesions will secrete fluid which later change the leaf color into black or purple alike. You must apply a copper-based fungicide on the leaves twice a week. Only apply it once a week if your Alocasia macrorrhiza’s position is outside especially in rainy season. It is necessary to control watering as wet soil and plant make this disease spreads faster.
It might not be the most dangerous plant disease, still it will make the plant looks less pretty. Rust-colored brown spots and faded patches on the leaves are the commonly seen signs. If the white cloth turns orange after you clean the leaves with it, the plant must be infected with rust.
To prevent the fungus from traveling through the plant tissues, immediately throw away the infected leaves, and then isolate the plant from others. Increase air circulation, reduce the humidity, and always keep the foliage dry would be enough to protect the plant.
Yellow Leaves with Brown Halos
One or combination of several problems here are the reason why this disease occurs.
- Placing the plant in a dark environment (less light)
- Use of cold water or tap water for watering
- Soil is lack of nutrient as a result of improper fertilization
- Overwatering that cause soggy soil
To tackle this matter, give the best fertilizer and watering the plant with the right water and amount regularly. Remove the infected leaves and just make sure to not repeat the bad habits or actions above.
Mild Toxicity Level
Calcium oxalate content in Alocasia macrorrhiza leaves is poisonous both for human and animal. Even though it only causes mild toxicity, consuming the plant in large quantities without properly cook it for a long time, might create a life-threatening situation. When it happens, quickly seek a medical assistance.
- On human, irritation or swelling in the mouth or throat, loss of appetite, nausea, GI tract, vomiting, or kidney stones, are the possible reaction when eating this plant. Children are prone to have an unwanted contact with this plant. Therefore, parents or adults around should keep an eye or simply put the plant away far from the kids.
- On animal, irritation in the mouth, swelling, and even breathing difficulties might occur after consuming the leaves, accidentally or not.
Dos and Don’ts When Growing Alocasia macrorrhiza
- No overwatering. It is a big no even during summer because later, it will result in a lack of oxygen for the plant. On the other hand, under watering is fine during cold weather or in a dark location.
- Follow a good watering schedule for a healthier plant. This tropical plant loves water. Use humidifier when you put it indoor to support a good humidity.
- Use lukewarm water for the sensitive ones. This plant is sensitive to fluctuating temperature, specifically extreme cold when root is the most affected part. It also sensitive to chlorine and fluoride. When only tap water is available, rest it overnight before giving it to the plant.
- Mist the plant regularly to keep the humidity. A dry condition will force the plant to go dormant. When the leaves turn brown, it is the sign to provide more humidity. If you do it excessively, the water will stay too long and weighing the stems and leaves.
- Keep the leaves shiny to support a good light absorption. Instead of using chemical leaf shine products, clean the leaves using damp cloth at least every few weeks. If it is growth in a dark, indoor area, dust or wash the plant monthly would increase its efficiency to capture the light.
- Add thin layer of gravel or grit for better drainage. Put the gravel or grit at the bottom of the soil in the pot.
- Overheard light position for better growth. Overhead lighting will allow the plant to grow upward as in its natural habitat.
- Avoid waterlogging by ensuring the size of drainage holes. The drainage holes below must be big enough to let the water flow outside easily.