Caladiums (Caladium bicolor) are tropical perennials that grow from tubers and are prized for their large, long-lasting leaves that come in combinations of green, pink, yellow-green and white. The midribs of the leaves are prominently colored; the edges of the leaves have contrasting colors.
Caladium cultivars come in two basic types. Fancy-leaved caladiums have large leaves in the shape of a heart that grow on long petioles, or stems. The elongated leaves of lance-leaved caladiums are smaller, thicker and more narrow, and grow on short petioles. Fancy-leaved caladiums grow from 12 to 30 inches tall; most lance-leaved caladiums are less than 12 inches tall.
Soil and Fertilizer
Caladiums like warm, moist, well-drained soil that is at least 70 degrees Fahrenheit; it should have a pH between 6 and 6.5. Incorporate a 2-to-3-inch layer of compost or pine bark mulch to improve drainage, aeration and add organic matter. The roots and foliage will not grow well if the soil is not well aerated. Mulch will also help conserve moisture. When you plant caladium in beds, add 1 to 2 lbs. of 8-8-8 or other complete fertilizer for each 100 square feet. That is 2 tbsp. per square foot.
Growing in Pots
Caladiums evolved to go dormant in the dry season. If they are allowed to wilt, they will lose their leaves. Plant them in a potting mixture that has peat to hold water and Perlite or sand to allow the mixture to drain.
Caladium tubers planted in cool soils of early spring will rot before they sprout. Start tubers indoors in moist potting soil or moist peat in shallow flats or flower pots. Four weeks before planting outdoors, cover the tubers with a thin layer of soil and put them in a brightly lit, warm room. Plant small tubers 2 inches deep and 8 inches apart; plant large tubers 12 inches apart. Put the knobby side up when you plant the tubers; the stems and shoots will emerge from the knobs. Leaves growing from the center or terminal bud of a caladium tuber are usually taller and larger than those growing from the lateral shoots.If you remove the terminal bud you will get a shorter, more uniform plant with a full canopy. Removing the terminal bud is most often done for caladiums grown in pots, not the landscape.
If you leave caladiums in the ground, the cold autumn weather will kill them. In the fall when the leaves begin to droop and lose their color and the temperature drops below 55 degrees F, dig the tubers up. Sort them by the color of their leaves and put them in area that is protected from the cold and rain but not in the full sun. Let them dry for a week. Cut the dry leaves from the tubers. Pack them lightly in dry sphagnum moss or in mesh bags that are used for oranges or onions and store them in an area with a temperature at least 70 degrees F. The plants will be less vigorous if you store them for more than 16 weeks before you plant them in the spring.
Buy tubers that are free of disease. Store tubers at room temperature to avoid problems with tuber rot. Fungi cause a chalky, dry decay; bacteria cause a slimy, soft rot. Anthractnose fungus can cause light tan to brown spots to develop on the lower leaves; get rid of those leaves immediately. A lack of water, too much sun or too much fertilizer can all cause older leaves to scorch and their edges to burn.