Elephant Ears, tropical plants in the genus Colocasia and Alocasia, are valued for their large, heart-shaped or arrowhead leaves. Native to tropical and subtropical regions, their corms (often incorrectly called bulbs) cannot endure freezing temperatures in most temperate climates. Gardeners in USDA Hardiness Zones 8 and colder must dig up the corms annually to protect them from cold damage and ensure survival until spring. Successful overwintering depends on precisely timed lifting, careful curing, and proper storage conditions.
Identifying the Optimal Time for Lifting
The most important indicator for when to dig up Elephant Ear corms is the death of the foliage caused by the season’s first light frost. Tropical plants suffer when nighttime temperatures consistently drop below 50°F (10°C). A light frost (briefly dipping to 32°F/0°C) causes the large leaves to collapse and turn brown. Waiting for this visual cue is important because the plant uses the final weeks of growth to transfer stored energy from the leaves and stems back into the underground corm.
This process signals that the corm has entered its natural dormancy period and is fully charged for winter. You must act quickly after the foliage dies back, as the corms are susceptible to damage if exposed to a hard freeze (below 28°F/-2°C for several hours). While the exact calendar date varies by USDA Hardiness Zone, the universal sign remains the visual collapse of the above-ground growth. Digging too early interrupts this energy transfer, potentially resulting in a smaller, less vigorous plant the next season.
Harvesting and Curing the Corms
Once the foliage has been killed by the first light frost, harvesting can begin. Start by pruning the remaining stems and leaves, cutting them back to four to six inches above the soil line. This short stem acts as a handle during lifting and helps prevent the corm from drying out too quickly during the initial curing phase.
To lift the corm without causing damage, use a garden fork or shovel and carefully insert it into the soil about a foot away from the base of the plant. Gently loosen the soil in a circle before using the fork to lift the root ball out of the ground. The corm’s skin is tender and easily bruised, so avoid piercing or scraping it. Open wounds can become entry points for pathogens during storage.
After lifting, gently brush off the loose soil clinging to the corm and roots. Do not wash the corms with water, as excess moisture increases the risk of fungal rot in storage. The corms must then undergo a curing period. This involves placing them in a warm, dry, and well-ventilated location, out of direct sunlight, for one to two weeks. The ideal temperature range for curing is between 60°F and 70°F (16°C and 21°C). This drying period allows the outer layer of the corm to heal minor abrasions and dry completely, preventing rot and mold during long-term dormancy.
Preparing Elephant Ears for Storage
After the corms have fully cured and the skin feels dry and firm, they are ready for final preparation before overwintering. You can dust the corms with a fungicidal powder or garden sulfur for protection against storage molds and rot. This step is recommended if you have previously experienced issues with corm loss during winter storage.
The storage environment must be cool, dark, and consistently dry throughout the winter. An ideal storage temperature range is slightly above freezing, between 40°F and 50°F (4°C and 10°C). Temperatures that are too warm can cause the corms to break dormancy early, while freezing temperatures will cause cellular damage.
The corms should be packed in a material that maintains a stable, low-humidity environment while allowing for air circulation. Suitable mediums include dry peat moss, vermiculite, or shredded newspaper. Place the corms in a cardboard box, paper bag, or mesh bag, ensuring they are surrounded by the packing material but not touching one another. Check the stored corms monthly for signs of shriveling (too dry) or soft spots and mold (excessive moisture).