A Case For Caladiums
August 3, 2010 
Caladiums not only make fantastic pot and hanging basket plants, but they’re a fast crop with a quick turnover. Starting with stored tubers, it’s possible to produce finished pot plants in six to 10 weeks.
Using prefinished materials, the production cycle can be further shortened. Growing a fast crop like caladiums brings multifold benefits: sizable reduction of costs on greenhouse heating, watering and fertilization, and extra flexibility to fill niche markets.
Historically, production and use of caladiums were mainly in the Southern United States because of their sensitivity to cold and frosts. Over the past decades, Florida growers, who supply more than 95 percent of the caladium tubers in the world, have built and expanded facilities for producing prefinished plants. Prefinished plants have been shipped as far as the Northern U.S. and Canada. Starting with rapidly growing prefinished materials, greenhouse growers–even those in northern, colder climates, can produce an eye-catching crop easily and profitably.
To meet the demand for caladium varieties, the University of Florida has run a caladium breeding program at its Gulf Coast Research and Education Center. This program has been the major organized breeding effort on caladiums in the world. Recently, a number of new varieties bred by this program have become available for greenhouse growers. With their new colors, leaf shapes and improved growth habits, these varieties can help greenhouse growers expand their plant palette for customers. Following is a brief description of a few of these varieties.
Fancy-Leafed Varieties
‘Cranberry Star’ produces attractive plants in all pot sizes. Leaves are bright white with purple to red spots, slender green veins and a narrow green border.
‘Firecracker Red’ plants are taller than other varieties and best suited for pots 6 inches or larger. It should be de-eyed for small pots. ‘Firecracker Red’ takes full sun and is suited for landscape planting.
‘Moonlight’ has bright white leaves and a very good pot plant habit. It’s well suited for all pot sizes and breaks well, even without de-eyeing.
Lance-Leafed Varieties:
‘Dr. Brent’ is an attractive red variety that produces much larger leaves and plants than ‘Red Ruffles’ and other red lance-leafed varieties. Leaves are bright red with white blotches scattered between main veins and bear some resemblance to watermelon flesh. Well suited for all pot sizes, ‘Dr. Brent’ sprouts about 10 days earlier than ‘Red Ruffles’ and is more tolerant to cold than other caladiums.
‘Tricolor Butterfly’ is a novel lance-leafed variety. Elongated leaves have thick dark green veins and cascade from the center like butterfly wings. Suited for all pot sizes, ‘Tricolor Butterfly’ does well in sunny or shady landscape settings. It takes two more weeks to sprout.
Production Tips
Caladiums are easy to grow and have few pest or disease problems. Costs on pesticides, fungicides, fertilizers or growth regulators are minimal, which makes caladiums a profitable crop for pot plant production. The following are some helpful tips for growers to produce high-quality products:
Start with stored tubers. Caladium tubers go through a natural period of dormancy after harvesting, and they should be cured and stored at 70 to 80°F for at least six weeks. Tubers not stored six weeks may take longer to produce saleable plants. Tubers should be healthy and firm, with bright yellow to creamy white flesh inside. Avoid those with internal discoloration, which is an indication of disease infection.
De-eyeing tubers. Removing or destroying the central eyes on caladium tubers has similar effects to caladium plants as pinching does to other flowering plants. It eliminates the dominance of the center bud and promotes the sprouting of surrounding buds. This practice results in a fuller, shorter plant with smaller but more uniform leaves. If larger plants or leaves are desired, de-eyeing may be not needed.
Keep them warm. Caladiums are tropical plants and they cannot tolerate cold. Tubers exposed to low temperatures become soft, rubbery and prone to rot. Cold injured tubers will be slow to sprout and produce fewer breaks. Severely injured tubers may not sprout at all. These injuries cannot be reversed by growing the injured tubers at warmer temperatures. It is critical that tubers are not stored, shipped or handled at temperatures below 70°F. Caladium plants should be forced at temperatures at least averaging 70°F and should not be below 65°F at night. Never ship caladium pot plants in refrigerated trucks or store the plants in cold rooms.
Water them regularly. Caladiums do best in a high peat potting mix with a good water holding capacity, and enough water should be applied daily to keep the potting mix moist to wet. It is not a good idea to withhold water to slow growth, reduce plant size or harden plants when growing caladiums. Water (and soil) pH should be between 5.5 and 6.5.
Feed them lightly. Caladiums should not be put on a constant liquid feed. Over-fertilization will cause “greening up” of white varieties, brown spots on leaves and even damage the color development (turning smoky and lacking luster). Liquid feed once at the spike stage and two weeks before shipment, using a solution of 200 ppm nitrogen from a complete fertilizer with a high ratio of potassium and micros (e.g. 10-10-15 plus), or incorporate one pound of 6-6-6 and one pound of minors per cubic yard into the potting soil.
Plant growth regulators. Some level of plant height control is possible with PGRs, but caladium plant responses vary between variety, greenhouse temperature as well as chemical, application method and time. PGR experts generally recommend application of paclobutrazol (Piccolo, Bonzi or Paczol) or flurprimidol (Topflor) products as a drench when 10 percent of planted tubers start to sprout.
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