ALOCASIA

DESCRIPTION

Historical Synonyms: Colocasia (1832), Ensolenanthe (1861), Xenophya (1863), Schizocasia (1880), Panzhuyuia (1985)

Alocasia is a genus of broad-leaved rhizomatous or tuberous perennial flowering plants from the family Araceae. There are 100+ species distributed from the subtropical eastern Himalayas throughout subtropical and tropical Asia into the tropical western pacific and eastern Australia

SUBSTRATE

Alocasia prefer a rich substrate that retains moisture while not getting excessively water-logged and anoxic:

A mix of peat moss/coco peat, perlite, pine fines or rice hulls, orchid bark and worm castings will work excellently for most growers. Advanced growers may see success with semi-hydroponic growing media as well (LECA, PON, etc.)

Additives like humic acid, systemic BONIDE granules or dolomitic lime can also benefit Alocasia, depending on species and individual growing conditions

FERTILIZATION

FERTILIZATION: Alocasia are heavy feeders and benefit from fertilization with every watering (the mantra weakly weekly works excellently). This can be done either:

externally with fertilizer added to watering solution (General Hydroponica Flora Series)
internally with slow-release forms of fertilizer added to the substrate (Nutricote, bone meal & blood meal)

DISTRIBUTION

Tropical Asia, Australasia, Malay Archipelago, Melanesia

Australia (Queensland, New South Wales), Bangladesh, Brunei, Burma, Cambodia, China (incl. Taiwan), Fiji, India, Indonesia (Borneo, Irian Jaya, Java, Moluccas, Sulawesi, Sumatra), Japan (incl. Ryukyu Is.), Laos, Malaysia (Borneo, Peninsula), Nepal, Papua New Guinea, Philippines, Solomon Is., Sri Lanka, Thailand, Vietnam.

CULTIVATION

ALOCASIA are a striking addition to any plant collection, offering some of the most distinctive ornamental foliage in the Araceae family.

They thrive under specific conditions, but are generally easy and rewarding to cultivate if those conditions are met.

PROPAGATION

Alocasia are easily propagated asexually. Healthy plants rapidly create offsets (also referred to as off-shoots or more colloquially pups), as well as propagative elements like terminal cormels (also referred to as corms). A larger rhizome can also be divided and propagated, similarly to how Monstera and Philodendron are propagated.

Sexual propagation (hybridization) in Alocasia has a rich history, dating as far back as the 1850s. While it takes a little more skill and luck to succesfully hybridize two Alocasia species or cultivars (intra-species hybridization is rarely worthwhile), it is a great way to select desirable qualities and create new and exciting plants. Please refer to the interactive dashboard at the bottom of this page for a complete list of existing hybrids.

ECOLOGY

CLIMATE: Generally found in tropical and subtropical humid forest

HABITAT: Alocasia grow predominantly in primary and secondary forests, early regrowth, open swamps, on the forest floor, in leaf litter, and sometimes in humus deposits on rocks.

With certain exceptions, Alocasia are usually found primarily in the lowlands, in everwet conditions, and in deep shade

GROWING CONDITIONS

TEMPERATURE: Like many other tropical genera, Alocasia prefer warm temperatures between 70-85°F (21-30°C). Anything below 50°F (10°C) is detrimental, while temperatures below 40°F (4°C) are injurious

HUMIDITY: 60-80% RH is recommended for optimal growth and maintaining an acceptable VPD (Vapor Pressure Deficit), though many growers have reported Alocasia will adapt to ambient humidity as low as 30% if needed (this will result in very high VPDs and nutrient burn is possible, so lighter fertilization is recommended)

WATERING: Substrate should be kept consistently moist and should never be allowed to dry out

LIGHT: When grown outdoors, shade cloth blocking 70-80% of sunlight is recommended. For plants grown indoor under artificial lighting, this is equivalent to about 2000-3000 FC (400-600 µmol) and is ideal for growth and flowering.

A minimum of 200 FC (40 µmol) is required for maintenance, though no growth will take place at such low light densities. While still considered low light, Alocasia will grow, albeit slowly, starting at 400 FC (80 µmol)

POTTING: It is of the utmost importance to not use pots that are too large for Alocasia. While other Araceae genera prefer or tolerate over-potting, Alocasia will readily rot and die off if the roots and rhizome are surrounded by too much wet substrate. This has to do with the way Alocasia grow their roots: in the corm or bare rhizome state, roots will form horizontally to anchor the plant, and then will begin extending downwards, rather than filling the pot radially.

Many growers are misled by the size of the foliage and let it decide the size of the pot, but the rule of thumb for Alocasia is to use the smallest/tightest pot that can fit the rhizome and existing root system, and perhaps 20-30% substrate. A longer, narrower pot is preferable to a shorter, wider one.

PESTS

As with most tropical plants, Alocasia are prone to infestations by a multitude of pests, particularly spider mites and thrips. For a complete list of pests and the recommended treatments please see the Pest Management Guide