This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Caladiums are a genus of highly ornamental plants of fine growth, easily cultivated, and requiring a strong moist heat to develop their beauties; they should be grown wherever ornamental and beautifully variegated foliage is admired.
As soon as the bulbs show signs of starting into growth they should be potted into good turfy loam, a little leaf-mould, well-decomposed cow-dung and sand, with a good addition of charcoal and bone meal. In potting, use clean pots, well drained, with a layer of moss over the crocks; fill up the pots fully one-half with a portion of the roughest soil, place the bulbs with a layer of sand at the base of each, and use the largest bulbs for the largest-sized pots, the size of which must be entirely regulated by the size of the specimens required - 12 to 18 inches being a good size for show plants or exhibition purposes, and small bulbs in 6-inch pots make good decorative plants - then fill up with some of the finer soil, pressing all gently down with the hand, and leaving plenty of room for water, which must be used very sparingly at first, till the plants throw out roots; and after they progress in size and strength the quantity can be gradually increased. A more vigorous growth can be induced by using guano-water occasionally; but we prefer shifting them into larger-sized pots when they become pot-bound, as the foliage loses part of its rich colour when stimulants are used.
When the sun is very strong they will require to be shaded, and gently syringed on fine days early in the afternoon, in common with the other occupants of the stove. They can also be well grown in a vinery, where room is a consideration, but they never develop their beauties so well under the shade of the Vines. As soon as they begin to fade in the autumn, less water should be given, gradually decreasing the quantity until it is entirely withheld. After growth has stopped, and the bulbs fully matured, the foliage should be all cleared away, and the pots put under the stage in the stove, or any other place with a cool, moist bottom, so that the roots can absorb a little of the moisture, which will keep the bulbs plump, and prevent the watering-pot being used so often during the time they are at rest. They must not at any time during the resting period be allowed to become dust-dry, or the corms will suffer, if not decay altogether. An early growth may be encouraged by potting early in the season, and plunging the pots in a strong bottom-heat, and maintaining a warm, moist atmosphere.
When any flowers make their appearance on the plants they should be instantly nipped off; and if an increase of stock is required, the bulbs can be divided with a sharp knife into small bits, with an "eye" to each, after growth has commenced. Dundonian.