Alocasia, frequently called Elephant Ear, is a popular houseplant beloved for its dramatic foliage, but growing it from a small, round reproductive structure can cause confusion. While often called bulbs, these underground storage organs are technically corms. The challenge lies in determining which end of the corm should face upward when planting to ensure successful growth. This guide provides clear instructions for orienting and planting the Alocasia corm for a healthy start.
Understanding the Alocasia Corm
What is often informally called an Alocasia bulb is technically a corm—a solid, swollen underground stem. This structure functions as a storage organ, packed with carbohydrates and nutrients the plant uses to survive unfavorable periods, such as dormancy. Unlike a true bulb (like a tulip or onion) made of fleshy, layered leaves, the Alocasia corm is composed of solid stem tissue.
The corm is a dense, compressed stem that stores energy and facilitates propagation. These corms, or cormels, typically separate from the parent plant’s main tuber or rhizome. Each corm is capable of growing into a genetic clone, making it essential to correctly identify the growth points for planting.
Identifying the Growth Points
The primary challenge is correctly identifying the apical end, or the top, where the new shoot will emerge. The top often has a slightly pointed or rough texture, sometimes displaying concentric rings or a distinct “nub” where a previous leaf or stem was attached. This growth point contains the dormant bud that will eventually push out a leaf.
The basal end, or the bottom, is typically smoother and more rounded. It may show remnants of old roots or the scar where the corm was attached to the mother plant’s rhizome. Roots will emerge from this basal end to anchor the new plant. A healthy corm should feel firm and should not have any soft or mushy spots, which indicate rot.
If the corm’s orientation is not immediately clear, plant it horizontally. The plant’s natural geotropism will cause the emerging sprout to orient itself upward toward the light. This approach eliminates guesswork for corms that are perfectly spherical or lack a distinct visual cue.
The Correct Planting Procedure
Once the top and bottom are identified, the corm should be planted into a well-aerated medium. Alocasia corms thrive in a light, airy, and well-draining soil mix to prevent waterlogging and rot. A blend of organic potting soil, perlite, and orchid bark, or a soilless medium like sphagnum moss or perlite alone, is effective.
The corm should be planted just beneath the surface, ensuring the identified growth point faces upward. Planting depth is shallow; the top of the corm can be barely covered with soil or left slightly exposed. Minimal disturbance during planting reduces the risk of damage to the growing tip.
A pot with adequate drainage holes is necessary to allow excess moisture to escape easily. The chosen medium must be pre-moistened before planting the corm to provide a hospitable environment without being saturated.
Immediate Post-Planting Environment
For the dormant corm to break dormancy and begin actively growing, specific environmental conditions must be met. High warmth is the primary trigger for sprouting, with temperatures consistently maintained between 75°F and 85°F. A seedling heat mat placed beneath the container can provide the necessary sustained warmth, especially in cooler indoor environments.
High humidity is equally important, mimicking the plant’s native tropical habitat and encouraging the outer shell to soften for the shoot’s emergence. Covering the container with a clear plastic dome or bag acts as a mini-greenhouse, trapping moisture to maintain humidity levels around 70 to 90 percent. Lift this dome briefly each day to allow for air exchange and prevent stagnant air, which encourages mold growth.
Initial watering should be executed with caution, keeping the medium barely moist but never soggy, as a dormant corm is susceptible to rotting. Sprouting can take several weeks, typically two to six, before the first visible signs of root growth or a leaf emerge. Consistent warmth and humidity are the factors that accelerate this process.