It's a pity caladium are rarely thought of as houseplants. These plants are almost unparalleled for their foliage. They have large, arrow-shaped and paper-thin leaves that come in a striking array of colors and patterns. A mass of caladium is an explosion of whites, greens, reds and pinks ... mottled, veined and striped. But these plants have a few drawbacks. They are tuberous plants that only grow foliage from spring to autumn, they require very high humidity, and they have absolutely no cold tolerance. Nevertheless, as far as unusual indoor plants go, these are sure to raise a few admiring eyebrows.
Light: Indirect light or moderate shade indoors. The narrower the leaves, the greater the sun it can withstand.
Water: When leaves appear, keep evenly moist. Never allow to dry out and keep humidity as high as practical.
Temperature: The warmer the better. Aim for 70º if possible—tubers begin to grow around 70ºF.
Soil: Rich, well-drained potting mix.
Fertilizer: Fertilize weekly during the growing season with liquid or use slow-release pellets.
Mature tubers can be divided; make sure that each new tuber section has at least one growing site.
Indoors or out, caladium are a seasonal plant, with foliage in the summer and a rest period in the autumn or winter. Their rest period isn't determined by temperature or light cycle, but by how long the plant has been growing. After the leaves begin to die back in the fall, either keep the tubers in the same pot (keeping it dry) or remove, clean and put into sawdust or sand to store. Store tubers above 55ºF to minimize loss of healthy tubers. Plant them out again when the next growing season begins.
There are literally too many cultivars to keep track of—caladium cultivars are green, red, pink, white, even orange. In many cases, cultivars are sold without names. Almost all cultivars are descended from the C. bicolor, which is native to South America. Some books list these plants as C. hortulanum. Personally, I buy caladiums for their foliage and don't worry too much about the cultivar.
Caladiums are a seasonal plant even in the tropics, where gardeners plant them in the spring and summer months when they'll thrive in the heat and wet. In the home situation, they'll do best with lots of heat, bright but indirect light, and lots of humidity. But even under the best conditions, caladiums will only last a few months before their leaves start to die back and the plant goes dormant again. This is OK—they're supposed to do that. Use masses of them as striking summer accents and conversation pieces. When they die back, save the tubers in a bag and replant next year for another show.