But caladiums have their limitations, particularly when it comes to temperature. A primary requirement is soil warmed to above 65° F, no surprise for a plant native to tropical South America. In cool climates, you certainly need sun to attain that level of warmth. Fortunately, several of the best varieties tolerate full sun beautifully as long as they get plenty of water.
Tall varieties such as white 'Candidum' and pink 'Carolyn Whorton' put on a beautiful show, but since each tuber has only one to three active buds, the leaf count is low.
Lance-leaved types, including 'Rosalie' and 'White Wing', produce many more leaves from multiple buds, but the leaves are thinner and not as long.
You can use caladium leaves in flower arrangements, where they will last two weeks or more. The trick is to soak the freshly cut stems in deep water in a dark place for 24 hours before putting them to work in a vase. Being pollen-free, caladium leaves are naturally nonallergenic.
If you live in a cool climate, it's important to grow sun-tolerant caladiums in a sunny spot from the beginning, or at least let the plants gradually become accustomed to the feel of warm sun on their leaves. Even with the most sun-tolerant varieties, if you grow plants in the shade and suddenly shift them into bright sun, existing leaves are likely to develop brown sunburned patches. However, the new leaves that replace them should look fine, and will turn your bed or patio into a technicolor tropical paradise.
To make watering and fertilizing easier, consider planting three tubers (or plants) in 6-inch pots and sink the pots up to their rims in the beds. The pots collect and hold water, stave off invasions from thirsty tree roots, and make it simple to lift and collect the tubers in fall.
Caladiums in full leaf need a steady supply of water. Plants that dry to the point of wilting will revive after a short dry spell, but forgotten plants may become dormant. Once dormant, caladiums will refuse to leaf out for at least eight weeks.
In USDA Hardiness Zone 7 southward, it's always warm enough to grow caladiums in outdoor beds; gardeners everywhere can growing caladiums in containers. Use a peaty potting soil, and plant three to five tubers upright in a 6-inch pot. Cover them with 2 inches of potting soil, soak once, and keep the pots in a very warm spot (70° to 80° F) for three weeks. Because the tubers like semidry conditions while they are breaking dormancy, water lightly, but don't let the soil dry completely.
The great advantage of pot-grown caladiums is that you can move them about as needed to keep them warm. When nights become chilly in fall, bring them indoors and keep in a sunny window, until the leaves begin to wither. At that point, let them dry out completely. To save space, you can collect the tubers, shake off the soil, and stash them in old hosiery or a mesh bag for up to five months. As long as the tubers are stored above 60d F, they will be ready to replant the following spring.
