Caladiums, often called “Angel Wings” for their vibrant, colorful, and heart-shaped foliage, are a popular choice for gardeners seeking to brighten up shady spots. The question of whether these plants are perennial or annual depends entirely on the climate in which they are grown. Caladiums are a classic example of a plant whose biological classification differs from its common horticultural treatment. Understanding this distinction is the first step in successfully cultivating this tropical beauty.
Defining the Caladium Life Cycle
The Caladium is biologically classified as a tropical, tuberous perennial, native to the humid forests of Central and South America. As a perennial, the plant is naturally equipped to live for more than two years, achieving this through a specific survival mechanism. The plant survives unfavorable conditions, such as periods of drought or cool weather in its native environment, by entering a period of dormancy.
During dormancy, all the plant’s energy is stored in a specialized underground stem structure called a tuber. This tuber functions as a storage organ, sustaining the plant through the resting phase until warmer, wetter conditions return. A true perennial, by definition, returns year after year without human intervention; however, the Caladium’s ability to do this is limited by its tropical origins.
The Role of Temperature and Frost
While Caladiums are perennials, they are generally treated as annuals across most of North America, specifically in temperate zones like USDA Hardiness Zones 3 through 8. This practical reclassification is necessary because the plant is extremely sensitive to cold temperatures. Caladiums cannot tolerate soil temperatures that consistently drop below 50°F (10°C) and are immediately killed by frost.
The plant’s foliage will begin to die back and collapse naturally as temperatures cool, signaling the start of its dormancy period. If the tuber is left in the ground in a region that experiences freezing temperatures, the cold will destroy the tuber’s stored cellular structure. The freezing of water within the plant’s tissues causes fatal cellular damage, meaning the tuber cannot survive to sprout again in the spring. Therefore, intervention is required in colder climates to prevent the cold environment from killing the plant’s survival mechanism.
Overwintering Caladium Tubers
To ensure a Caladium behaves like a perennial in a cool climate, the tubers must be lifted and stored indoors before the cold weather sets in. The best time to begin this process is in the fall, either when the foliage naturally begins to yellow and die back, or immediately after the first light frost has caused the leaves to collapse. Waiting until the leaves begin to yellow allows the plant to naturally pull maximum nutrients back into the tuber for storage.
After carefully digging up the tubers, it is important to remove large clumps of soil, but the foliage should not be cut off immediately. The entire plant should be placed in a warm, dry, and sheltered location for a “curing” period of one to two weeks. This curing process allows the leaves to completely dry out, helping to seal any minor wounds on the tuber and preventing rotting during storage.
Once the foliage is completely dry, the dead leaves and any fine roots can be cleanly removed from the tubers. Only firm, healthy tubers should be saved; any that feel soft or mushy should be discarded. The prepared tubers should then be placed in a ventilated container, such as a cardboard box, and covered with a dry, insulating medium like peat moss, vermiculite, or sawdust.
The storage location must be kept consistently warm, with temperatures ideally ranging between 55°F and 65°F (13°C to 18°C), and be completely dry to prevent rot. The tubers should be checked periodically throughout the winter to ensure they remain firm and free of mold or decay. In the spring, four to six weeks before the last expected frost, the tubers can be replanted indoors in containers to jumpstart their growth, ensuring a vibrant return to the garden once the soil temperature warms to at least 70°F (21°C).