Tropical plants which are grown for the sake of their large, ornamental leaves; they are natives of South America and belong to the Arum family, Araceae. The leaves, which develop annually from tubers, are heart-shaped and richly colored and vary from 6 in. to 2 ft. in length; the flowers are interesting but of minor importance. The origin of the name is obscure. For Caladium esculentum see Colocasia.
Pot Culture. Throughout their growing season, Caladiums need a warm, moist atmosphere. The minimum indoor temperature should be 75 degrees during the summer and 55 degrees during the winter. The tubers are started into growth February—March. They are shaken free from the old soil, set in a flat of leaf mold or peat moss and covered with similar material. As soon as roots are forming freely the tubers are taken out of the box and potted separately in 4-in. pots. After potting they are kept in a warm, moist atmosphere, shaded from hot sunshine, syringed and carefully watered until the roots reach the sides of the pots; then they are repotted in 5 or 6-in. pots, according to their size and vigor.
The best potting compost consists of loam, two parts, and equal parts of peat, leaf mold and dried cow manure. The remainder of the summer treatment consists in keeping the greenhouse moist by moistening the floor and benches frequently and by syringing the leaves of the plants in the morning and afternoon. When the pots have become filled with roots, liquid fertilizer may be applied with advantage twice a week. If the leaves become overcrowded a few of the weak or poorly colored ones may be removed. They are good window garden plants.
Treatment in Winter. Towards the end of the summer when the leaves begin to fade, water is gradually withheld; finally the leaves die down. The pots containing the tubers are then stored in a cellar or other convenient dry, moderately warm place until February or March when the tubers should be started into growth in the way explained. The soil must not be watered while the tubers are dormant.
Outdoor Culture. In the South, Caladiums are splendid plants for outdoor cultivation. The tubers are planted 2 in. deep and 8-12 in. apart in rich, reasonably moist soil in a lightly shaded position that is sheltered from strong winds, as soon as the weather is settled and warm. In the North, tubers may be started into growth indoors 8 weeks before the weather is warm enough to set the plants outdoors; the young plants are grown in pots for greenhouse or window garden decoration and are set in the garden in a shady position, in fairly moist, rich soil when the weather is really warm and settled. They need plenty of moisture during the growing season. In fall, before killing frost, they are lifted, dried off, and are stored over winter as advised for pot-grown plants.
Propagation is effected by dividing the tubers after they have started into growth in spring The pieces of tuber are set in a box covered with sifted leaf mold or peat moss and kept moist and warm. As soon as the pieces possess roots they should be potted separately in 3-in. pots.
The Chief Kinds. These are the chief species (the color description refers to the leaves): C. Humboldtii (argyrites), a charming plant, 6-8 in. high, with green and white leaves; C. bicolor, green and red; C. Schomburgkii, green and white; C. Chantinii, variously colored.
Those chiefly grown are named varieties which have been raised in gardens. Some of the most handsome are Ace of Hearts, red and green; Candidum, white with green veins; John Peed, metallic-red and moss-green; Macahyba, green and red with lilac spots; Marie Moir, white with red blotches.