Elephant ears, belonging to the genera Colocasia and Alocasia, are tropical plants prized for their dramatically large foliage. Gardeners in cooler climates must start these heat-loving corms indoors to significantly extend their growing season. This practice allows the plant to develop a substantial root system and large leaves before outdoor temperatures are reliably warm enough to support robust growth. Getting a head start indoors, typically four to six weeks before the last expected frost, ensures the plant reaches its impressive mature size by mid-summer.
Selecting and Preparing the Elephant Ear Bulb
Select a healthy corm (bulb or tuber) that feels very firm and heavy for its size. Avoid any corms with soft, mushy, or moldy spots, as these indicate rot that will likely prevent successful sprouting. Before planting, gently remove any dry, papery outer layers, which allows the corm to absorb moisture more efficiently once potted.
Identifying the correct planting orientation is a frequent point of confusion, but the corm has distinct ends. The bottom, or root end, is typically rough or slightly flattened, where the roots will emerge. The top end, where the shoot will sprout, is usually smoother, sometimes slightly pointed, or may show concentric rings. If the corm appears extremely dry, a brief, one-hour soak in lukewarm water can help rehydrate it, but excessive soaking must be avoided to prevent rot.
The Indoor Planting Process
Choose a container 6 to 8 inches in diameter, only slightly larger than the corm, ensuring it has excellent drainage holes. Using an oversized pot can lead to the soil staying too wet, which is a major cause of corm rot before the roots have developed. Fill the container with a light, well-draining potting mix enriched with organic matter.
The corm should be planted shallowly, placing the rough, root end down and the smooth or pointed end facing upward. Cover the top of the corm with only one to two inches of soil, or leave the very top exposed, which helps prevent moisture from accumulating around the growing point. Water the soil thoroughly until it is evenly damp, allowing excess water to drain completely. Avoid overwatering; the soil should feel like a wrung-out sponge, consistently moist but never saturated.
Maintaining Optimal Sprouting Conditions
Elephant ear corms require high heat to break dormancy and initiate the sprouting process. The ideal soil temperature for rapid sprouting is consistently between 70°F and 80°F. Placing the pot on a seedling heat mat is the most reliable way to maintain this warmth, as ambient room temperature is often insufficient for tropical plants.
During the initial phase before a shoot appears, the corm does not need bright light; warmth is the primary catalyst for growth. Once the first sprout emerges above the soil, move the container to a location that receives bright, indirect light, such as a sunny window. Monitor the soil moisture closely, allowing the top inch to dry slightly between waterings, but never allowing the entire pot to desiccate. Sprouting can take three to eight weeks, so patience is necessary during this period of subterranean growth.
Hardening Off and Transplanting
Once the danger of the last frost has passed and nighttime temperatures are consistently above 50°F, the sprouted plants must be acclimated to outdoor conditions. This process, known as “hardening off,” gradually introduces the plant to direct sun, wind, and temperature fluctuations. Begin by placing the container in a shaded, sheltered location for a few hours each day, bringing it inside every evening.
Over seven to ten days, progressively increase the time the plant spends outdoors and the intensity of the light it receives. The elephant ear is ready for its final outdoor location when the soil temperature is at least 65°F. Plant the corm at the same soil depth it was growing in the pot, choosing a spot with rich, moist soil and exposure that ranges from full sun to partial afternoon shade.