Elephant Ear plants (Colocasia and Alocasia) are prized for their tropical foliage. Native to warm regions of Southeast Asia and the Pacific, their growth and survival are dictated by temperature. Understanding their thermal tolerance is necessary for successful cultivation, especially in temperate climates.
Minimum Cold Tolerance
The primary factor limiting the range of Elephant Ears is their low tolerance for cold. When temperatures consistently drop into the 50°F to 60°F (10°C to 15°C) range, the plant enters dormancy, signaled by the foliage yellowing or wilting. This dieback is a natural physiological process where the plant conserves energy in its underground storage structure.
The corm or tuber is sensitive to freezing. The underground structure will not survive a hard frost or prolonged soil temperatures near 32°F (0°C). Elephant Ears are reliably perennial only in USDA Hardiness Zones 9 through 11, where the ground does not freeze. In cooler zones, they are typically grown as annuals or must be protected during the winter months.
Planting should be delayed until the soil temperature reaches a minimum of 65°F (18°C) in the spring. Planting in cold, wet soil can lead to the corm rotting before it sprouts. Visible signs of cold stress, such as yellowing leaves, should prompt immediate action to protect the root system.
Managing Dormancy and Overwintering
When the first light frost is anticipated in cooler climates, prepare the plant for winter storage. Wait until a light frost causes the foliage to die back naturally, then cut the stems back to two to six inches above the soil line. This signals the end of the growing season and allows the plant to fully withdraw energy into the corm.
The corms or tubers should be carefully dug up, starting about a foot away from the base to avoid damage. Brush off excess soil and allow the tubers to air-dry in a cool, sheltered location for several days to a week. This curing process helps the exterior skin to toughen and minimizes the chance of rot during storage.
For storage, pack the dried corms in a breathable, insulating medium like dry peat moss, wood shavings, or vermiculite inside a cardboard box or paper bag. The ideal storage location is a dark, dry, and frost-free area, such as a basement or garage. The temperature must remain consistently between 50°F and 60°F (10°C and 15°C) to prevent freezing and ensure the corm remains dormant until replanting in the spring.
In warmer regions (Zone 7b and above) where hard freezes are infrequent, overwintering the plant directly in the ground is an alternative. After the foliage dies back, trim the stems and cover the area with a thick layer of insulating mulch, generally three to six inches deep. This heavy layer of organic material protects the corm from sporadic dips in temperature and helps regulate the soil temperature.
Maximum Heat and Sun Exposure
While Elephant Ears are native to the tropics, their large leaves are susceptible to damage from excessive heat and direct, intense sunlight. Most varieties perform best when daytime temperatures are consistently between 70°F and 85°F (21°C and 29°C), which supports their rapid growth cycle. However, exposure to the harshest midday sun, particularly in climates where temperatures routinely exceed 90°F (32°C), can be detrimental to the foliage.
Intense, direct sun exposure during the peak hours of 10 AM to 4 PM can cause sun scald, which appears as browning, crisping, or bleached spots on the leaves. Alocasia varieties, which tend to have more upright and thinner leaves, are often more prone to this type of damage than the broad-leafed Colocasia. Gardeners in hot regions should therefore aim for a planting location that receives bright morning sun followed by afternoon shade or all-day dappled light.
The link between high temperature and water management is inseparable for these plants. Due to their expansive leaf surface area, high heat significantly increases the rate of evapotranspiration, meaning the plant loses water quickly. Maintaining consistently moist soil is paramount for survival in hot weather, as the plant needs to replace the water lost through its large leaves to prevent wilting and dehydration. Container-grown plants in particular may require daily watering to keep the soil from drying out under the intense heat.