Caladiums for the Home Garden

Caladiums (Caladium bicolor, and Caladium x hortulanum) are tropical members of the arum (Araceae) family. Like their thick-leaved cousins, the elephant ears (Alocasia spp., Colocasia spp., and Xanthosoma spp.), caladium leaves are heart or arrow-shaped. Unlike the elephant ears, caladium leaves are thin and brightly colored with speckles, streaks, or splashes of pink, red, white, and green. Although caladiums are native to South America, they are neither invasive nor aggressive in the continental United States. Like all members of the arum family, caladium leaves contain insoluble calcium oxalate crystals that will cause an oral irritation, like drooling, if eaten by a pet. These crystals are considered toxic, but not lethal.

Caladiums fall into two broad categories: strap-leaf and fancy-leaf. The strap-leaf varieties have narrower foliage and are often more sun-tolerant. The fancy-leaf types have larger, heart-shaped leaves and prefer filtered shade. They tolerate morning sun but require afternoon shade. Both types have similar cultural needs, in containers or in garden beds.

Growing Conditions

The harsh afternoon sun will scorch the thin leaves of caladiums. They thrive best in partial shade but appreciate a bit of morning sun. Avoid strong midday and late afternoon sun. A few newer cultivars are bred for sun tolerance, but even these need protection from bright sunlight.

A loose, well-draining, moist soil is essential. In garden beds, incorporate organic matter, such as compost or fine pine bark, to create well-draining yet moist soil. In containers, use high-quality potting mix amended with coir or peat moss, and supplemented with fine pine bark. Heavy clay soils will trap water and cause rot.

Temperature

Caladiums are true tropical plants that require warmth. Please do not rush to plant them in the spring, as they will sulk, and even rot, rather than thrive. Wait until temperatures are well over 70°F, with soil temperatures at least 68°F.

Fertilizer and Water

Always keep the soil or potting media evenly moist but never saturated. Soggy soil, especially early in the season when tubers are waking up, leads to root rot. Allowing the soil to dry out causes leaf droop and brown edges.

Use a balanced, slow-release fertilizer when planting caladiums, or apply a diluted liquid fertilizer every month during the plant's active growth period. A fertilizer high in nitrogen may cause green leaves, rather than brightly colored leaves, so select a balanced or slightly low-nitrogen formula.

Mulch

A thin layer of pine bark mulch, pine straw, or shredded leaves helps maintain moisture that caladiums crave. Apply less than 1 inch of mulch in containers and 1 to 2 inches in garden beds.

Problems

Caladiums are trouble-free, but if stressed, they may attract spider mites or aphids. Keep them well-watered, shaded, and warm to stay pest-free. If the caladium produces small flowers, remove them. The plant's energy should go into producing colorful leaves.

Dormancy and Overwintering

Caladiums are considered annuals in our area. You can purchase them as tubers or as potted plants from nurseries. In USDA Plant Hardiness Zones 10 and 11, caladiums are perennial plants. It is essential to pay attention to the autumn weather if you want to overwinter caladiums in Pennsylvania. Even a light frost will not only kill the foliage, but it will also damage the tubers!

As the weather cools and day length shortens, caladiums naturally go dormant. The foliage starts to yellow and collapses. This indicates that it is time to gently dig out the tubers. Brush off the soil or potting media, and place the tubers in a warm, dry location for 1 to 2 weeks. Curing helps dry the outer layer of the tubers, reducing the risk of rot during storage. After curing, remove the remaining soil and trim off dry leaves or roots.

Store the tubers in mesh bags or very shallow boxes layered with dry peat moss or pine shavings. Keep the tubers in a moderately cool, dry environment. Take care that the temperature never drops below 60°F, as cold can cause the tubers to die. As spring approaches, start the caladium tubers indoors in pots. Remember that caladiums thrive in heat, so do not rush to move the plants outdoors.

Caladiums are true tropical plants. Some tropical or semi-tropical plants can be overwintered in much cooler environments.My unheated basement successfully stores canna (Canna spp.), dahlia (Dahlia spp.), gladiolus (Gladiolus spp.), angel's trumpet (Brugmansia spp.), and an ornamental red banana (Ensete ventricosum 'Maurelii') through the winter until spring. It is much too cool for caladiums, so I purchase new plants annually.

Penn State Master Gardeners always encourage plant parents to put the right plant in the right place. Part of determining that the right plant is in the right place is to read all the information on the plant tag. Caladiums became the perfect plant for the cast-iron kettle on my north-facing front porch. One year, I purchased a single beautiful dark red and green caladium in a small pot without a tag. Oh dear! It turned out to be a very large variety that completely overwhelmed its much smaller white companions. Oops! Now, I am much more careful about what I buy.