Any garden with a shady location has a perfect spot for caladiums. These tropical tubers, most of them varieties derived from Caladium bicolor, are grown for their dramatic summer foliage. They are naturals in beds with ferns or coleus, in pots to accent shady spots, or indoors as knock-your-socks-off houseplants.
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.
Until fairly recently, caladium varieties could be neatly divided into tall fancy-leaved and shorter lance-leaved types. Each has special talents and uses. Tall kinds such as white 'Candidum' and pink 'Carolyn Whorton' put on a beautiful show, but since each tuber has but one to three active buds, the leaf count is low. De-eyeing tubers (removing the terminal buds on the tuber when it first spikes to encourage side buds to develop) before planting will increase leaf numbers. Lance-leaved types, including 'Rosalie' and 'White Wing', produce many more leaves from multiple buds, but the leaves are thinner and not as long.
At the University of Florida's Gulf Coast Research Station in Brandenton, Gary Wilfret has spent 25 years breeding caladiums that combine the best of both types and are custom-made for growing in containers. Of the eight varieties released so far, pink-and-green 'Florida Sweetheart' is his runaway hit, with red-and-green 'Florida Red Ruffles' poised to enter the big time as soon as growers accumulate sufficient stock. Besides its vigorous leaf production, 'Florida Red Ruffles' may have a slight edge in terms of cold tolerance. Wilfret's long-term goal? To extend caladiums' growing range into climates where nighttime temperatures drop below 55° F.
Because 80 percent of caladiums are now grown in containers, which can be moved about as needed to expose the plants to the warmth they need, give them a try no matter where you live.
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.
When slender spikes push through the soil, move the pots to bright light, indoors or out, and start giving them more water. As long as temperatures stay above 70° F, the leaves should quickly unfurl.
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.
Because caladiums are basically all leaves, they thrive on regular fertilizer. To keep plenty of new leaves coming on, mix a balanced soluble fertilizer such as 10-10-10 into the watering can twice a month while plants are growing well.
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, near a sunny window, until they look as if they need a rest. 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 60° F, they will be ready to replant the following spring.
In the warm, humid climates of southern zones 8 and 9 (National Gardening zones Middle, Lower, and Tropical South), plant caladium tubers directly into the ground in spring. In most other areas, you'll save several weeks of growing time by transplanting potted plants that are already up and growing.
Plant in soil that is moist, well drained, humus rich, and slightly acidic. Caladiums are popular grown around the bases of trees, but for this planting scheme to work, you will need to create a 5-inch-deep bed of rich soil so the tuberous roots will have adequate space and a fair chance at moisture.
To make watering and fertilizing easier, plant three tubers (or plants) in 6-inch black plastic pots (nursery liners) 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.
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.
Name; Type; Use; Colors
'Aaron'; Tall fancy-leaved; Beds; White; medium green edge.
'Carolyn Whorton'; Tall fancy-leaved; Beds; Pink, green, red.
'Red Flash'; Tall fancy-leaved; Beds; Red, green; white speckles.
'Florida Sweetheart'; Interspecies hybrid; Beds, pots; Pink; green edge.
'Miss Muffet'; Interspecies hybrid; Beds, pots; Cream; red speckles .
'White Wing'; Short lance-leaved; Beds, pots; White; green edge.
It's true. 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.
As common in the Deep South as buttermilk biscuits are the huge green leaves of a caladium relative, elephant's ear (Alocasia), which grows to 8 feet tall in rich, moist soils. It is hardy to zone 8. Few plants are more dramatic when grown at the edge of a water garden, but any moist, shady spot will do.
Barbara Pleasant, a freelance garden writer who lives in northern Alabama, wrote the National Gardening Regional Report from the Middle South.
Photography by Mike MacCaskey
Article published on June 23, 2008.