How to Grow and Care for Alocasia Macrorrhizos

Alocasia macrorrhizos, commonly known as the Giant Taro or Upright Elephant Ear, is native to the rainforests of Southeast Asia, New Guinea, and Queensland. It makes a statement with its large, upward-pointing leaves that can stretch up to four feet long on sturdy, upright stems. Its size and structural beauty make it a popular choice for those looking to add a bold element to their gardens. This guide will walk you through the specifics of nurturing this plant.

Essential Care Requirements

Light

Providing the right amount of light is fundamental to the health of an Alocasia macrorrhizos. This plant thrives in bright, indirect sunlight, which mimics the dappled light it would receive on the rainforest floor. An ideal indoor location is near an east-facing window for gentle morning sun, or a few feet from a south or west-facing window. This placement ensures the plant gets the brightness it needs without the risk of damage from harsh, direct rays. Too much direct sun can lead to scorched or yellowed leaves, while insufficient light will cause slow growth and weak, “leggy” stems.

Water

Proper watering is a delicate balance for the Giant Taro, which prefers soil that is consistently moist but never waterlogged. Check the top inch of the soil; if it feels dry to the touch, it is time to water. During the active growing season of spring and summer, the plant will require more frequent watering. When the plant enters its dormant period in the fall and winter, its water requirements decrease significantly. Overwatering is a common pitfall that can lead to root rot, so it is better to err on the side of underwatering.

Soil

The soil for an Alocasia macrorrhizos must support both moisture retention and excellent drainage. Standard potting soils are often too dense and can hold excess water. A well-draining, airy, and nutrient-rich potting mix is ideal. You can create this by amending a peat-based mix with components like perlite, vermiculite, or pine bark, which improve aeration and drainage. This allows water to flow through, preventing the soil from becoming compacted while still holding enough moisture.

Temperature and Humidity

As a plant of tropical origin, the Giant Taro flourishes in warm and humid conditions. The ideal temperature range for this species is between 65°F and 85°F (18°C to 29°C). It is not frost-tolerant and must be protected from temperatures that dip below 50°F (10°C). Place the plant away from areas with fluctuating temperatures, such as near heating vents, air conditioners, or drafty doors. This Alocasia has a high appreciation for humidity, and increasing the ambient moisture will promote more vigorous growth. You can raise humidity by using a humidifier, placing the pot on a pebble tray filled with water, or grouping it with other tropical plants.

Fertilizer

To fuel its growth during the spring and summer, Alocasia macrorrhizos benefits from regular feeding. A balanced, water-soluble houseplant fertilizer is recommended, applied every two to four weeks and diluted to half-strength to prevent root burn. Only fertilize during the active growing season. As the plant’s growth slows in the fall and winter, it enters dormancy and does not require supplemental nutrients. Fertilizing a dormant plant can damage the root system.

Propagation Techniques

Propagating Alocasia macrorrhizos is done through the division of its underground rhizome. This process is best undertaken in the spring or summer when the plant is actively growing, often coinciding with repotting. To begin, carefully remove the entire plant from its pot and gently shake off the excess soil. This will expose the rhizome so you can look for natural offsets, often called “pups,” which are smaller plants that have formed their own roots.

Using a clean, sharp knife, carefully separate a pup from the main rhizome, ensuring the division has a healthy section of rhizome and a viable root system attached. Pot the new division into an appropriately sized container with fresh, well-draining potting mix. Keep the soil lightly moist and place the plant in a warm spot with high humidity and bright, indirect light to encourage new growth.

Troubleshooting Common Issues

Yellowing leaves are a common concern and most often point to overwatering, so always check the soil’s moisture level first. Other causes for yellow leaves can include underwatering or the natural aging process where older leaves die off. Drooping stems are a clear signal that the plant is thirsty, and a thorough watering will usually cause them to become upright again. Severe drooping can also be a symptom of root rot from overwatering.

Brown, crispy leaf edges are a sign of low humidity or inconsistent watering. Brown spots, rather than just edges, can indicate leaf scorch from exposure to intense, direct sunlight.

Giant Taro can be susceptible to pests, with spider mites being a common issue. These pests thrive in warm, dry conditions and can be identified by fine webbing on the undersides of leaves. To combat them, regularly wipe the leaves with a damp cloth or insecticidal soap and increase the humidity around the plant.

Toxicity for Pets and Humans

Alocasia macrorrhizos is toxic to cats, dogs, and humans if any part of the plant is ingested. The toxicity is due to the presence of insoluble calcium oxalate crystals within the plant’s tissues. When chewed or ingested, these crystals embed themselves in the soft tissues of the mouth and throat, causing an immediate and painful reaction.

Symptoms of ingestion include:

• Intense oral irritation
• Swelling of the lips, tongue, and mouth
• Excessive drooling
• Difficulty swallowing

Place the plant in a location that is safely out of reach of curious pets and small children. If you suspect that a pet or child has ingested any part of the plant, contact a veterinarian or a medical professional immediately.