It is a family of about 60-70 rhizomatous shrubs from the rainforests of Borneo, Malaysia and mainland Asia. Alocasia macrorrhiza plants have a fleshy and elongated stem and large heart-shaped or elongated and pointed leaves, even larger than 30 cm and light green, dark green or purple, depending on the variety, carried on long rigid petioles, usually slightly arched.
The flowers are similar to the inflorescences of the callae, with long spatium covered by a green spathe, they bloom in summer, and in autumn they originate only one roundish fruit, containing only one seed, not always fertile. The specimens cultivated in pots hardly produce flowers.
With the passing of the years, they tend to form a short and stocky woody stem; the colour of the leaves of the species is bright green, but there are many cultivars on the market, with dark green, yellowish green foliage, with the margin or the veins in contrasting colour. Due to their shape, they are also called Ears of elephant.
Origins and habitats Alocasia
Halocarsia is a beautiful plant suitable for growing indoors or in a heated greenhouse. It is much appreciated for its vigour and for the “exotic” aspect that it is able to give to our house.
The genus Alocasia, belonging to the Araceae family, is native to East Asia; it includes about 70 species of evergreen herbaceous plants. They grow mostly in tropical and subtropical rainforests, so they need a mild climate, with no major temperature changes between summer and winter. Living at the foot of the forest, they require luminous expositions, but without direct sun and a strong ambient humidity.
All these aspects (especially the high level of 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 constantly heated and humidened greenhouse or veranda (like those for orchids), with other plants of the same type.
To the genre halocarynx belong to a few dozen rhizomatous plants, originating in Malaysia and other tropical areas of Asia, generally grown in Europe as indoor plants. From the rhizome to the… this genus includes about three hundred species of succulent plants, originating in southern Africa; there are species that can reach conspicuous dimensions, such as species of very small size…
In apartment it is advisable to grow Alocasia macrorrhiza plants in a bright, but partially shady, place; the optimal temperature should be around 20-25 degrees for the whole year. Sometimes in winter, if the temperature is too low in the house, the plants of elephant ears the leaves, which grow back in spring, are completely lost and the rhizomes tend to enter a period of vegetative rest. Avoid exposing specimens of Alocasia macrorrhiza to strong air currents, which could burn the leaves.
Some varieties of elephant ears they can bear the cold quite well, but they fear the frost, therefore they can be grown in the garden, provided the rhizomes are kept in a temperate place during the cold months. If we decide to grow these plants in the garden, they can also be placed in a place where they are exposed to direct sunlight, but not for excessively long periods of time.
This plant needs extremely bright expositions, but without direct sun.
Inside it is good to place it near a window facing south (and screened with a light curtain during the summer). In summer, it is best to place it under the broadleaf trees on the outside, with a slightly filtered light.
LA ALOCASIA IN BREVE
Famiglia, genere, specie
Araceae, General Alocasia, circa 70.
Known as “elephant’s ears.”
Type of plant
Type of plant
Southeast Asia: Philippines, Malaysia, Indonesia, Madagascar
Tropical and subtropical rainforests
Persistent (in tropical habitat): dark green, light green, black, purple, silvery
Erect or rounded
Indoor plant, greenhouse, veranda, tropical garden
Height at maturity
From 50 cm to 2 metres, depending on the variety
Speed of growth
10°C (withstands 0°C by losing the aerial part)
Ideal temperature in the growing season
Very bright, no direct sunlight
30% leaf soil, 20% compost, 10% perlite, 20% sand, 20% garden soil
Every 30 days, rich in potassium
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 winter if the house is very heated. From March to October add fertilizer to the water of watering every 10-15 days, with the arrival of cold thinning the administration once a month.
During the winter months, especially for those specimens that have lost their foliage, let’s avoid watering excessively, moistening the soil only when it is very dry. As far as the specimens grown outdoors are concerned, during the cold months the rhizomes are extracted from the soil and kept in a dry, cool and dark place until the following spring.
Halocaryosia always requires slightly moist soil: it is very important to avoid that the ground bread dries completely, otherwise it will cause serious damage. Watering should be abundant and constant, especially during the summer and if we maintain high temperatures in our apartment. The best results are obtained with rainwater or demineralized 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 the Alocasias produce many fragile roots, which need a loose soil in order to develop, it is therefore appropriate to use universal soil mixed with peat, leaves and sphagnum, which ensure a soft and light soil.
The substratum must be rich, but well drained, with a subacidic 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% leaf soil, 20% well-decomposed manure or compost, 10% perlite, 20% sand and 20% clayey garden soil. In this way we will be able to keep the roots always fresh, but, at the same time, we will avoid dangerous water stagnations.
The multiplication of these plants takes place in autumn by division of the rhizomes, which usually produce shoots throughout the growing season. The new small plants are to be kept in a warm and humid place till the following spring, when they can be repotted in a fairly big pot; usually, containers with a diameter exceeding the 30-35 cm are utilized.
During the repotting we separate the young jets that have formed on the sides, keeping a piece of rhizome. Let’s invade it immediately, avoiding to insert it too deeply.
During the repotting we cut, with a clean and well sharpened knife, some segments of rhizome, making sure that each one has at least one bud. Let’s place them horizontally (without burying them) on a soil that retains moisture well. Let’s buy with transparent plastic, so that the humidity remains high. Ideally, we should place everything at a constant temperature of 25°C. After the jets have developed, we can pot them individually.
IL CALENDARIO DELLA ALOCASIA
All year round or from March to October
Pests and diseases
Nutritional deficiencies cause rapid yellowing of the leaves, which are often also attacked by aphids and cochineal. It is possible to intervene manually to eliminate cochineals with the use of a cotton ball with alcohol, or use special insecticide products.
The most common parasites are the Cotton ladybirds that attack already debilitated specimens (especially from too low winter temperatures). Let’s fight them with specific products such as white oil and endotherapy insecticides.
Low ambient humidity can cause the arrival of the red spider: frequent vaporization often reduces the impact. Otherwise we use specific acaricides.
General characteristics Alocasia
Alocasia, commonly called “elephant ears”, are formed by erect stems ending in large, thick, outward-facing leaves, oval or sagittate in shape. In some species and cultivars, they are even more striking thanks to the veins in evidence, with contrasting colours. We can find them in many shades: from light green to dark green, black or silver. Even more appreciable are those that have the back of a beautiful purple.
If grown under ideal conditions they can also flower, producing a beautiful light green spathe.
In its natural environment it can grow up to 5 metres in height: in a pot, at best, it stops at 2 metres.
As we have said, it is a plant native to the rainforests: in order to live well we must reproduce those conditions as much as possible. Ideally, temperatures should always be between 20 and 35°C, but remember that the warmer the environment, the higher the humidity level.
The best results are obtained in temperate greenhouses, which are constantly heated and humidified, or in well-exposed verandas.
In apartment the plant is also suitable for living in a temperature range between 15 and 25°C. Always remember, however, that halocsia fears the cold, which can cause serious damage (such as the complete drop of leaves). This problem can also be caused by cold air currents. The minimum recommended temperature is 10°C, but the plant can bear even 0°C, however losing the entire vegetative apparatus (while the rhizomes will remain viable).
Halocsia requires a very humid atmosphere, otherwise the leaves will dry out and be lost. In the house we can meet them by vaporizing them several times a day with demineralized water. Electric humidifiers or humidifiers to be placed on radiators can also help. It also benefits from saucers filled with water and expanded clay. A suitable environment can often be achieved by keeping a large number of plants close together.
All these tricks can be applied also for the cultivation in greenhouse or in veranda, as well as during the summer, when the specimens can be moved outside.
FOGLIAME DIMENSIONI E PORTAMENTO
Dark green with metallic reflections and silver ribs, wavy edges. Retro purple
Up to 1.20 m, upright posture
Alocasia x amazonica ‘Polly’
Elongated dark green, evident silver-coloured veins
Up to 70 cm, suitable for apartment.
Compact and rounded appearance
Velvety dark green, purple retro
Up to 50 cm, very compact, very suitable for indoor use
Carved edge, dark green, evident light green veins
Up to 1.50 m in an apartment, even 2 outside or in a greenhouse. Beautiful majestic appearance
Bright green, curled and shiny, very large, ribs in evidence.
Up to 2 metres inside, up to 5 metres in the ground
Alocasia plumbea ‘Nigra’
Thick, shiny, curled, very dark purple
From 90 to 150 cm, upright
Growing Alocasia in the garden
Halocarynx can be moved outside during the summer, when the minimum temperatures do not drop below 15°C.
It is ideal to place it near other plants (gunnera, rodersi, darmera, calle, arum), so that a high humidity is guaranteed. It is good to put it near mirrors of water, with essences from the swamp. In this perspective it is also possible to put it in the ground, using it as an annual or multi-year (if we live in the southern regions, where it never freezes, and prepare a thick mulch in winter).
Alocasia repotting system
It is advisable to repot the newly purchased halocarsia: in fact, they are usually placed in very small pots, with too peaty substrates and the irrigations, often, are not properly cared for. For plants already in our possession we should preferably proceed in April, every two years, when the roots come out from the drainage holes.
We choose a large pot and prepare a thick drainage layer. We insert the plant (trying to disturb the roots as little as possible) without burying the collar too much (easy to rot) and we fill with the substrate that we have prepared.
Ears of elephant – Alocasia macrorrhiza: Fertilization Alocasia and other cures
Having a rapid growth it needs a good support: we distribute always, 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 (it will help the maintenance of the “rigid” structure of the leaves).
The leaves, which are large and quite rough, become, over time, a receptacle for dust. This can lead to a slowdown in growth. They can be cleaned with a soft, damp cloth. Alternatively, it is recommended to “shower” the plant or place it outside during a not too violent storm.
L Alocasia does not require pruning. However, it may be necessary to remove dry, diseased or damaged leaves. Let’s remove them directly from the base, using a sharp, clean and disinfected scissors.
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