Alocasia Macrorrhizos - Elephant Ears


Alocasia macrorrhizos



Contents

  1. Top Tips
  2. Location, Water, Humidity & Fertilisation
  3. Common Issues
  4. Origins, Temperature, Propagation, Repotting & Toxicity.

For queries or questions, comment in the section below or send us a message via this link!




Top Tips & Info

  • Care Difficulty - Easy
  • Alocasia macrorrhizos are best equipped for locations that provide bright, indirect light. Areas that are too dark will significantly increase the risk of root rot, along with slowed growth and yellowing older leaves.
  • Allow the top third to dry out in between waters, reducing this further in the autumn and winter. Over-watering during its dormancy period is a common issue among owners, so always bear this in mind when the colder months arrive.
  • Fertilise fortnightly during the spring and summer, and monthly for the rest of the year using a houseplant-labelled fertiliser.
  • Keep an eye out for Spider Mite that'll form webs on the under-leaves of the plant.
  • Especially with those kept in a dark location, wash or dust the foliage monthly to increase the light-capturing efficiency.
  • Repot biannually, using Houseplant soil or a general-purpose compost with some perlite. Introduce some grit for larger specimens to strengthen their root system.




Location & Light - 🔸🔸🔸

Although bright, indirect light is best, throw in some morning or evening sun if possible to help deter over-watering. Positions that are too dark will present many issues, ranging from lopsided growth, soil mould and root rot. For those who are worried about its location being too dark, if a newspaper can be read while having your back towards the window, you're good to go! Provide over-head lighting for balanced, vertical growth which can be achieved in a semi-heated conservatory.


Water - 🔸🔸

Allow the soil's top third to dry out in between waters, reducing this further in the autumn and winter. Remember, it's always better to under-water an Alocasia macrorrhizos than over-do it when situated in shady or cooler areas. When irritating, use lukewarm water as their roots systems are quite sensitive to temperature change. Although rainwater is best, if you decide to use tap water, allow it to stand for 24hrs to eliminate both chloride and fluoride. Large quantities of the chemicals will gradually build up in the soil over the course of several months, damaging the overall plant health and its soil quality. Under-watering symptoms include stunted growth, brown leaf edges and yellowing leaves. These issues are commonly caused by being pot bound, too much sunlight or heat, or pure forgetfulness. Over-watering symptoms include a collapsed base, yellowing older leaves, mouldy soil and plant death. If you feel that root rot is to blame, remove the affected leaves, roots, and soil, and replace with a fresh batch of houseplant compost. Click on this link for more info about addressing this disease.


Humidity - 🔸🔸

Create a humidity tray while the heaters are operating to provide a moist and stable environment for your plant. If the surrounding saturation is too low or the heat too high, its leaf-tips may start to brown over and curl, especially in direct sunlight. Hose the foliage down from time to time to hydrate the leaves and keep the dust levels down.


Fertilisation - 🔸🔸

Feed twice a month in the growing period and monthly in the autumn and winter to replicate its dormancy period. Either use a houseplant-labelled feed, or a general plant fertiliser at half the recommended strength. Never apply a 'ready to pour' feed without a quick drink beforehand as the combination of dry soil and harsh chemicals may lead to root burn and yellowed foliage.



A beautiful A. macrorrhizos in the Adelaide Botanic Gardens


Common Issues with Alocasia Macrorrhizos

Regular irrigations are key. Periods of droughts will quickly slip the plant into its dormancy period, causing stunted growth and a bewildered plant owner. If it hasn't repotted in a while, there may be too many roots and not enough soil to retain moisture, thus leaving the soil to dry out quicker. Click on this link to learn more about a transplant.

Pests could arise at any time, with infestations starting from the original nursery or via contamination in your home. Spider Mite and Mealybugs tend to be the usual inhabitants, with the first being minute and almost transparent, roaming the leaves in search of chlorophyll and a site to hide its eggs. The latter, however, will stand out much more, with white cottony webs developing across the foliage and stems. Thoroughly check the plant's cubbyholes before giving it the all-clear, or click on the appropriate links to learn more about eradicating these issues.


Typical damage of Spider Mites


Older leaves that rapidly become yellow are a clear sign of over-watering, usually caused by too little light, with other symptoms include mouldy or heavy soil, stunted growth and a rotten base. Although Alocasia macrorrhizos can be placed in darker locations, the frequency of irrigations must be reduced to counteract the chance of root rot. People don't realise that a plant's root system needs access to oxygen too; when soil is watered, the air will travel upwards and out of the potting mix. A lack of accessible oxygen will cause them to subsequently breakdown over the oncoming days. Click on this link to learn more about root rot and how to address it.

Curled leaves and brown leaf-edges are the result of too little water and over-exposure to the sun. Alocasia macrorrhizos are best located in bright, indirect settings, and those that haven't acclimatised to the harsh rays will show signs of sun-scorch and environmental shock. A splash of winter sunlight is acceptable as long as the soil moisture is regularly observed, with complete avoidance once summer comes along.

Due to the species' sensitivity to chemicals, Leaf Shine shouldn't be used to improve the appearance of the foliage, and instead should be cleaned via a rinse of lukewarm water. Failure to do so may cause yellowed, mottled spots that cannot be undone.

Yellowing sections along its leaves could be the product of many issues, ranging from spider mite to chemical burns. Think about its recent cultivation of how frequently you rehydrate its soil, along with a quick scan over the foliage's undersides. The use of 'Leaf Shine' or other chemical-based products may also have a detrimental effect on its health, as Alocasia macrorrhizos are particularly sensitive to inorganic substances. When removing the affected leaf or leaves, be sure to avoid puncturing the yellowed/browned tissue as it may lead to further decline. Prune the entire leaf off via the petiole and investigate the rest of the plant for a potential spread of the problem. If you still need further advice regarding this matter, be sure to send us a message via this link!

Clean the leaves regularly. Although this isn't too much of an issue, a build-up of dust particles can clog up the plant's pores, causing lowered light capturing-efficiency. Rinse the topsides of the leaves down once a month to keep levels down and improve growing conditions.

Too low humidity can cause browning tips with yellow halos on juvenile leaves. Although this won't kill your specimen, you may want to increase the local moisture to prevent the new growth from adopting these symptoms. Mist or rinse the foliage from time to time and create a humidity tray while the heaters are active to create a stable environment. The browning of leaf-tips on older leaves is wholly natural and is the product of extensive photosynthesis during its life.

Mould developing on the soil means two things - too little light and over-watering. Despite the harmlessness of the mould, it'll prove unsightly to most gardeners and is therefore removed once known. To remove, replace the top two inches of the soil for a fresh batch of houseplant compost. Either increase the amount of light received (no direct sunlight for the first few weeks to prevent environmental shock) or decrease the frequency of waters slightly. If the mould is accompanied by yellowing lower leaves, you may also have a case of root rot.




Origins

Alocasia macrorrhizos was initially described as 'Arum macrorhizum' by Carl Linnaeus in 1753, before being switched by George Don in 1839 into the newly constructed 'Alocasia' genus. The species' epithet refers to large rhizomatous growths that'll emerge within the mother's rhizosphere.

If the corm (modified basal organ) is sufficiently cooked, it'll provide high levels of starch, used as energy in the body. The corms are used in 'Binagol' cuisine, whereby it is mashed and added to rice, nuts and coconut milk to make a well-known Filipino delicacy.


The Distribution of Alocasia macrorrhizos


Temperature

10° - 30°C   (50° - 86°F)
H1b  (Hardiness Zone 12)  - Can be grown outdoors during the summer in a sheltered location with temperatures above 12℃  (54℉),  but is fine to remain indoors, too. If you decide to bring this plant outdoors, don't allow it to endure any direct sunlight as it may result in sun-scorch and dehydration. Regularly keep an eye out for pests, especially when re-introducing it back indoors.


Spread

Up to 3m in height and 1.5m in width, with the ultimate height being reached in around 5 - 10 years. Alocasia macrorrhizos are best grown with overhead lighting to compliment their growth structure; locations with lateral light sources (e.g. the corner of a room) will cause stunted, lopsided growth.  


Pruning & Maintenance

Remove yellow or dying leaves, and plant debris to encourage better-growing conditions. While pruning, always use clean utensils or shears to reduce the chance of bacterial and fungal diseases. Never cut through yellowed tissue as this may cause further damage in the likes of diseases or bacterial infections. Remember to make clean incisions as too-damaged wounds may shock the plant, causing weakened growth and a decline in health.


Propagation

Via Seed, Stem Cuttings (only for mature specimens) or Basal Offset Division.

Basal Offset Division (Easy) - Your plant will produce several basal offsets that can be separated once they have a sufficient root system with at least three leaves. If possible, water the soil 24hrs before the main event to reduce the risk of transplant shock, when its dry root systems are over-fingered. Take the plant out of its pot and place your fingers close to the nodal junction - compost may have to be removed for better access. Push the chosen offset downwards until you hear a snap. Separate the foliage and its root system away from the mother plant, mentally noting the high risk of damage. Transplant in the appropriate sized pot with a fresh batch of 'houseplant' compost. Maintain evenly moist soil and situate it in a bright, indirect location away from any direct sunlight. After six weeks, treat it like a normal specimen, following the care tips above!


Flowers

Much like a Peace Lily's flower body, their flowers consist of a white or green spathe (the spoon-like shell) with the spadix being the site of pollination. Blooms can last up to five days and are usually visible during late spring or early summer around 30cm+ from the soil line.


An example of its flower.


Repotting

Repot every two years in spring using a houseplant-labelled compost and the next sized pot with adequate drainage. Hydrate the plant 24hrs before the tinkering with the roots to prevent the risk of transplant shock. For those that are situated in a darker location, add a thin layer of small grit in the compost's lower portion to improve drainage and downplay over-watering. Click here for a detailed step-by-step guide on transplantation, or via this link to learn about repotting with root rot.

If you're still unsure of what to do, never hesitate to send us an email or direct message to get our expert advice on transplantation.


Pests & Diseases

Keep an eye out for mealybugs, spider mite, scale, thrips & fungus gnats that'll locate themselves in the cubbyholes and undersides of the leaves. Common diseases associated with all Alocasia are root rot, leaf-spot disease, botrytis, rust, powdery mildew & southern blight - click here to learn more about these issues.


Toxicity

This plant is classified as poisonous due to varying concentrations of calcium oxalate crystals found around the plant's body. If parts of the plants are eaten, vomiting, nausea and a loss of appetite could occur. Consumption of large quantities must be dealt with quickly; acquire medical assistance for further information.


Retail Locations

Some garden centres will sell this variety of Alocasia, but the most reliable locations are online.



If you need further advice with indoor gardening, never hesitate to send us a message or leave a comment in the section below. This could be about your own specific plant, transplantation into a bigger pot, pests or diseases, terrarium ideas, & more!




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