It is a family of about 60-70 rhizomatous shrubby plants, originating from the rainforests of Borneo, Malaysia and continental Asia. The plants of Alocasia macrorrhiza have a fleshy and elongated trunk and large heart-shaped or elongated and pointed leaves, of a size even greater than 30 cm and of a light green, dark green or purple color, depending on the variety, carried on long rigid petioles, generally slightly arched. The flowers are similar to the inflorescences of the calla lilies, with a long spatice covered with a green spade, they bloom in summer, and in autumn they give rise to a single round fruit, containing a single seed, not always fertile. Hardly potted specimens produce flowers. Over the years they tend to form a short, stocky woody stem; the color of the leaves of the species is bright green, but there are very many cultivars on the market, with dark green, yellowish green foliage, with the border or veins in contrasting color. Due to their shape they are also called elephant ears.
Alocasia origins and habitat
Alocasia is a beautiful plant suitable for growing indoors or in a heated greenhouse. It is much appreciated for its vigor and for the "exotic" appearance that it can give to our home.
The genus Alocasia, belonging to the Araceae family, is native to eastern Asia; it includes about 70 species of evergreen herbaceous plants. They mostly grow in tropical and subtropical rainforests: therefore they need a mild climate, without large changes in temperature between summer and winter. Living at the foot of the forest requires bright exposures, but without direct sun and strong environmental humidity.
All these aspects (especially the high humidity) are difficult to reproduce in our homes and the plant unfortunately tends to have a short life. The ideal would be to grow it in a greenhouse or veranda constantly heated and humidified (like those for orchids), with other plants of the same type.
In the apartment we suggest growing the plants of Alocasia macrorrhiza in a luminous, but partially shaded place; the optimum temperature should remain around 20-25 degrees throughout the year. Sometimes in winter, if at home the temperature is too low, the plants of elephant ears they completely lose their leaves, which grow back in spring and the rhizomes tend to enter a period of vegetative rest. Avoid exposing the specimens of Alocasia macrorrhiza to too strong air currents, which could burn the leaves.
Some varieties of elephant ears they tolerate the cold quite well, but they don't like frost, so they can be cultivated in the garden, provided they put the rhizomes in a temperate place during the cold months. If you decide to grow these plants in the garden they can also be placed in a place reached by sunlight, but not for excessively long periods of time.
This plant needs extremely bright exposures, but without direct sun.
Inside it is good to place it near a window facing South (and shielded with a light curtain during the summer). In fine weather, outside, it is good to place it under the deciduous trees, with a lightly filtered light.
ALOCASIA IN BRIEF
|Family, genus, species||Araceae, gen. Alocasia, about 70. Known as "elephant ears"|
|Type of plant||Type of plant|
|Origin||Southeast Asia: Philippines, Malaysia, Indonesia, Madagascar|
|Habitat||Tropical and subtropical rain forests|
|Foliage||Persistent (in tropical habitat): dark green, light green, black, purple, silver|
|Habit||Erected or rounded|
|Use||Indoor plant, greenhouse, veranda, tropical garden|
|Height at maturity||From 50 cm to 2 meters, depending on the variety|
|Minimum temperature||10 ° C (withstands 0 ° C losing the aerial part)|
|Ideal temperature in the vegetative period||20-35 ° C|
|Exposure||Very bright, no direct sun|
|Ground||30% earth of leaves, 20% compost, 10% perlite, 20% sand, 20% garden soil|
|Fertilizer||Every 30 days, rich in potassium|
|Soil moisture||Always fresh|
|Environmental humidity||Very high|
They must be very abundant, it is good to keep the soil always moist; it is advisable to vaporize the leaves often with distilled water, especially in summer, when the days are warmer, and in the winter if the house is very heated. From March to October, add fertilizer to the irrigation water every 10-15 days, with the arrival of the cold thin out the administration once a month. During the winter months, especially with regard to the specimens that have lost their foliage, we avoid watering excessively, moistening the soil only when it is very dry. As for the specimens grown outdoors, during the cold months the rhizomes are extracted from the soil, and are kept in a dry, cool and dark place until the following spring.
The alocasia always wants slightly damp soil: it is very important to prevent the ground bread from drying out completely, otherwise serious damages. The irrigations must be abundant and constant, especially during the summer and if we keep the high temperatures in our apartment. The best results are obtained with rainwater or demineralised water, at about 25 ° C.
During the winter, if we encourage a period of vegetative rest with low temperatures and moderate light, we can reduce the interventions a little, but always carefully monitoring the general health of the plant.
The rhizomes of Alocasie produce many fragile roots, which need a loose soil in order to develop, therefore it is advisable to use universal soil mixed with peat, leaves and sphagnum, which guarantee a soft and light soil.
The substrate must be rich, but well drained, with a sub-acid pH. We can use a product designed for green plants, but the ideal is to produce it ourselves. A good mix is obtained with 30% of earth of leaves, 20% of well decomposed manure or compost, 10% of perlite, 20% of sand and 20% of clay garden soil. In this way we will always be able to keep the roots fresh, but at the same time we will avoid dangerous water stagnation.
The multiplication of these plants occurs in autumn due to the division of the rhizomes, which usually produce shoots during the whole vegetative season. The new plants should be kept in a warm and humid place until the following spring, when they can be repotted in a fairly large pot, generally using containers larger than 30-35 cm in diameter.
During repotting we separate the young jets that have formed at the sides, keeping a piece of rhizome. Let's invade it right away, avoiding putting it too deep.
During the repotting we cut, with a clean and well sharpened knife, some rhizome segments, making sure that everyone has at least one gem. Let's put them horizontally (without burying them) on a soil that retains moisture well. We buy with transparent plastic, so that the humidity remains high. The ideal is to put everything at a constant temperature of 25 ° C. After the jets have developed we will be able to pot them individually.
THE CALENDAR OF THE ALOCASIA
|Vegetative rest||November to March|
|Composting||All year round or from March to October|
Pests and diseases
The nutritional deficiencies cause a rapid yellowing of the leaves, which are often also attacked by aphids and cochineal. It is possible to intervene manually to eliminate the scale insects with the use of a cotton swab with alcohol, or use special insecticide products.
The most common parasites are the cottony scale insects that attack the already debilitated specimens (especially from too low winter temperatures). Let's fight with specific products such as white oil and endotherapeutic insecticides.
Low environmental humidity can cause the arrival of red spider mites: frequent vaporizations often succeed in reducing their impact. Otherwise we resort to specific acaricides.
General characteristics of Alocasia
The alocasia, commonly called "elephant ears", are formed by erect stems that end in large and thick leaves, facing outwards, oval or sagittate. In some species and cultivars they are even more showy thanks to the ribs in evidence, with contrasting colors. We can find them in many shades: from light green to dark green, black or silver. Even more noticeable are those that have a nice purple back.
If grown in ideal conditions they can also bloom, producing a nice light green spate.
In its natural environment it can grow even up to 5 meters in height: in pot at best it stops at 2 meters.
As we have said, it is a plant native to the rainforests: because we live well we must reproduce those conditions to the maximum. The ideal is that the temperatures always go between 20 and 35 ° C: let us remember, however, that the more the environment will be warm, the more the humidity must be high.
The best results are obtained in temperate greenhouses, constantly heated and humidified, or in well-exposed verandas.
In the apartment the plant adapts to live even in a range of temperatures between 15 and 25 ° C. Let us always remember, however, that alocasia fears cold, which can cause serious damage (such as the complete drop of leaves). This problem can also be caused by currents of cold air. The minimum recommended temperature is 10 ° C, but the plant can withstand even 0 ° C, losing however the entire vegetative apparatus (while the rhizomes will remain vital).
The alocasia expects a very humid atmosphere, on pain of drying up and the loss of the leaves. At home we can come to meet you by vaporizing it several times a day with demineralized water. Electric humidifiers or radiators can also be helpful. It also benefits from water-filled and expanded clay pots. A suitable environment is often achieved by keeping a large number of plants close together.
All these tricks can also be applied for cultivation in greenhouses or on the veranda, as well as during the summer, when the specimens can be moved outside.
DIMENSIONS AND PORTAMENTO
|Sanderian alocasia||Dark green with metallic reflections and silver ribs, wavy edges. Purple back||Up to 1.20 m, erect habit|
|Alocasia x amazonica 'Polly'||Stretch dark green, evident silver-colored ribs||Up to 70 cm, suitable for apartment. Compact and rounded habit|
|'Black Velvet'||Velvety dark green, purple back||Up to 50 cm, very compact, very suitable for interiors|
|'Calidora'||Carved border, dark green, clear light green ribs||Up to 1.50 m in the apartment, even 2 outdoors or in greenhouses. Beautiful majestic bearing|
|Alocasia macrorrhiza||Bright green, curled and shiny, very large, veins in evidence.||Up to 2 meters inside, up to 5 in full ground|
|Alocasia plumbea 'Nigra'||Thick, shiny, curled, very dark purple||90 to 150 cm, erect|
Grow Alocasia in the garden
Alocasia can be moved outside during the summer, when the minimum temperatures do not fall below 15 ° C.
Ideal is to place it next to other plants (gunnera, rodersi, darmera, calle, arum), so that high humidity is guaranteed. Beautiful it is to place it near bodies of water, with swamp essences. In this perspective it is possible to put it also in the open ground, using it as an annual or multi-year (if we live in the southern regions, where it never freezes, and we prepare a thick winter mulch).
It is advisable to repot the newly purchased alocasia: in fact they are usually placed in very small pots, with too peaty substrates and irrigations are often not properly cured. For the plants already in our possession we proceed preferably in April, every two years, when the roots come out of the drain holes.
We choose a large pot and prepare a thick draining layer. We insert the plant (trying to disturb the roots as little as possible) without burying the collar too much (easy to rot) and fill it with the substrate we prepared.
Elephant ears - Alocasia macrorrhiza: Fertilization Alocasia and other cures
Having a rapid growth it needs a good support: we always distribute, or only during the vegetative period (depending on the temperatures we keep in winter), once a month, a liquid fertilizer for green plants, where the potassium is predominant (will help the maintenance of the "rigid" structure of the leaves).
The leaves, large and quite rough, become, over time, a receptacle of dust. This can lead to a slowdown in growth. They can be cleaned with a soft damp cloth. Alternatively it is advisable to "shower" the plant or place it outside during a storm that is not too violent.
Alocasia does not require pruning. However, it may be necessary to remove dry, diseased or damaged leaves. Let's eliminate them directly from the base, using a sharp, clean and disinfected scissors.
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