This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
Amongst the numerous plants which are highly deserving of more universal cultivation, and a greater degree of attention, than is usually bestowed upon them; the Gloxinia stands conspicuous in an eminent degree. Although plants are to be met with in many collections, it has but rarely been in that state of perfection of which it is susceptible, being, for the most part, subjected to only the ordinary treatment of a miscellaneous collection of greenhouse plants.
The plants comprehended in the natural order, to which the Gloxinia belongs, are many of them, inhabitants of deep-shaded dells, or of their immediate vicinity, in the tropical parts of the world. Many of them have their habitation on old decayed logs, and other rich decaying vegetable matter, while others grow upon more elevated and exposed situations: the genus under consideration belongs to that section which thrive, in all their native luxuriance, in the deep shaded valleys of Pernambuco.
To cultivate it with success, the following conditions demand especial attention: that the roots be allowed abundant means of spreading in a horizonital direction; in order to effect this, I have used large garden pans, or feeders, in lien of pots, for the last shift, with the best success. If large specimens for exhibition, or otherwise, were desired, I use them of the size of twelve inches over, and five deep, allowing one inch for effectual drainage, which must be strictly attended to throughout their entire growth, from the seed, or cutting, as the case may be, to the final shift into the flowering pans.
The first process of raising the plants is by cuttings (leaves, with the entire petiole attached); this can be done at any time after the leaves have attained their full development, which, under ordinary circumstances, will be from June to August - the earlier in the season, the better, in order that the young bulbs may become sufficiently strong to put forth their lovely blossoms in abundance during the ensuing season.
Fill the cutting pots, to within three inches of the top, with broken crocks; upon these a layer of sphagnum (bog moss); then fill to the rim with clean sand, and saturate with water; afterwards, insert the cuttings (leaves), removing them to a gentle hotbed, being careful to shade during the warmest part of the day; in this situation they may remain until they have attained a sufficient size to transplant, which should be done into two-inch pots, using a compost of decayed vegetable mould, with about one-third sandy loam, which should have the additional care of being well and effectually drained. When potted, they are again placed in a gentle hotbed, until sufficiently established to be placed in the greenhouse, where they may remain until the leaves die down; after which, they maybe placed under the stage of the greenhouse, being careful to place the pots upon their sides, in order to prevent any moisture coming near the bulbs, and not too near the flue, as this would cause the buds to shrivel up; in this situation they may remain until the following March or April, when they may be repotted, being careful to shake all the mould from their roots; to the above-named soil, add one-third of partially decayed wood with a few uneven pieces of charcoal, which, while they have the effect of retaining moisture about the roots, will also be the means of facilitating the escape of any which might be superfluous.
When repotted, place them in a shady part of the stove, or propagating-house, in a close and moderately warm atmosphere, paying attention to repotting as often as the plants require it, until finally removed into the flowering pans.
During their growth throughout the spring, and, indeed, until the flowering is over, keep them in a position where they can enjoy a partial shade, with a temperature of from 60° to 80°. As the season advances, the shady part of a greenhouse will be all the protection they will require; indeed, protected, in a cold frame, during the warmest part of the day, from the sun's rays - in such a situation, they will perfect their lovely blossoms, and last's much longer period in bloom than if left in the stove or greenhouse. The period at which they will be in bloom, if such a coarse be adopted, will be from about the end of June until September, varying as their maturity may be encouraged or retarded.