Caladiums are tropical plants native to South America, known for their striking, colorful foliage. They thrive in warm, humid conditions but are typically grown as annuals in temperate climates. Since caladiums cannot tolerate cold, their underground tubers must be lifted and stored indoors for the winter season in regions below USDA Zone 9 or 10. Overwintering protects the tubers from freezing, allowing them to survive the dormant period until spring. Successful storage requires careful attention to timing and handling to ensure the tubers remain viable.
Identifying the Ideal Time for Lifting
The ideal time to lift caladium tubers is determined by falling temperatures and the plant’s natural life cycle. Begin the process when nighttime temperatures consistently drop below 60°F (15°C). Exposure to temperatures much lower than this, especially a hard frost, can damage the tubers.
A primary visual indicator is when the foliage naturally starts to yellow and die back, signaling the plant is entering its dormant phase. This decline means the plant has finished seasonal growth and is redirecting energy back into the tuber. Waiting for this natural senescence is important because lifting actively growing tubers prevents the full maturation and hardening of the tissue. If cold weather is imminent while the foliage is still green, lift the tubers immediately to protect them from frost damage.
Preparing and Lifting the Tubers
The physical process of lifting the tubers must be executed gently to avoid mechanical damage. Start by cutting the foliage back, leaving a short stem of about one to two inches attached to the tuber cluster. This stub serves as a handle and helps mark the top of the tuber for later planting.
Use a garden fork or shovel to carefully loosen the soil in a wide circle around the plant, ensuring the tines do not pierce the tuber mass. Since caladium tubers grow shallowly, often just a couple of inches below the surface, a gentle approach is necessary. Lift the entire cluster, keeping the bulk of the surrounding soil intact to protect the delicate structure during the initial drying phase. Lightly knock off the loose soil after lifting, but avoid washing the tubers with water, as moisture can encourage rot.
Curing and Preparing for Storage
The next stage after lifting is curing, which dries the outer layers and allows minor wounds to heal. This step is important for preventing fungal infections and rot during storage. Place the tubers in a warm, dry, and well-ventilated location, such as a garage or protected porch, for approximately five to seven days.
The ideal curing temperature should remain above 60°F (16°C) to facilitate proper drying. During this time, the remaining foliage will shrivel, and the tuber surface will harden. Once cured, gently brush away any remaining soil and inspect the tubers for soft spots or signs of rot. Some gardeners dust the clean tubers with a fungicide or sulfur powder for protection against storage molds.
Proper Winter Storage Conditions
The final step is placing the cured tubers into a suitable medium and environment for their dormant rest. The primary goal is to maintain a cool, dry temperature that prevents them from freezing or sprouting prematurely. The preferred temperature range for dormant storage is ideally between 55°F and 65°F (13°C to 18°C).
The storage medium must be completely dry and surround the tubers to absorb residual moisture. Appropriate materials include:
- Peat moss
- Dry vermiculite
- Newspaper shreds
- Clean sawdust
Store the tubers in ventilated containers, such as paper bags, cardboard boxes, or mesh sacks, ensuring air circulation. This prevents the buildup of excess humidity or ethylene gas, which promotes decay. Check the stored tubers monthly throughout the winter for signs of shriveling, indicating conditions are too dry, or mold, suggesting poor ventilation.