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.
If there is any one branch of his business that the gardener ought to pay more attention to than another, I think it should be the decoration of the various structures under his care during the dreary and dull months of gloomy winter; for this purpose, to those who have a store, I know nothing better adapted than the Gesnera. With the beautiful qualities of a foliage plant, it possesses also deservedly the character of a free bloomer. There is thus a twofold reason why it claims our attention; and well-grown plants, either large or small, will abundantly repay any attention they require at our hands to make them so. One of my late worthy employers, who, by the way, was passionately in love with especially such flowers as had real worth to recommend them, who was also a good bit of an artist, declared, after viewing it from all its view-points, admiring and readmiring its charms, "that Gesnera refulgens is the handsomest thing I ever saw".
I do not by any means suppose that in my mode of culture there is anything particular or peculiar, but as I am under the impression that a good many young gardeners maybe at a loss as to how they are to treat those things they may have this year for the first time under their care, it is for their benefit that I now pen my own mode of treatment. After the plants have done blooming, say in February, they will indicate a desire to go to rest, and no time should be lost in allowing them to do so, consistently with their being thoroughly ripened, which is a most material matter for the wellbeing of the plants during the following season, as half-ripened roots can never start again with the same vigour as thoroughly ripened ones do; and on the start they make much depends. Water must now be very sparingly given, at the same time not withholding it altogether at once, but giving it at long and then at longer intervals, until their tops are quite dead, when they may be cut down, and the pots turned over on their sides in a warm dry corner of the stove, where no water at all can by any accident reach them. There it is necessary they should remain to rest for at least a month or six weeks, or even longer, if they are not wanted very early for next year.
There are some gardeners who, when their plants have done blooming, at once cut them over, and perhaps throw in below the stage or some other such place. Such treatment is far wrong, as the tubers are not ripe when their tops are done blooming, and therefore they ought to be carefully and prudently treated until they are perfectly ripe. I generally like to have an early and a late lot, and therefore start them at different periods, five or six weeks intervening.
From the middle to the end of March I consider a good time for starting the first lot, and for this I of course take those that have first gone to rest. Having prepared a suitable compost - that is, one part good turfy loam from the top spit of an old pasture, one-third leaf soil, one-third well-rotted cow-dung, and one-third rough peat, this latter to keep the whole nice and open, so that abundance of water can be given without souring the soil in any way - the next object is to get suitable pots, clean both outside and inside, and well crocked, to insure a free passage for the water. This, especially in the case of Gesneras, is a most essential matter, as they are very impatient of stagnant water or sour soil. The size of the pots must be entirely regulated and determined by the kind of specimens wanted; mine generally range from 4 to 10 inch pots, in which latter I have had specimens ranging from 2 to 3 feet through, which I found large enough when thickly studded with blooms, as I always get them under the above treatment. The pots being, as I have already directed, well crocked, are now filled with the said soil to about 2 1/2 inches of the brim, the roughest of the compost placed in the bottom of the pots.
The pots containing the tubers are now brought to the potting bench, the dried ball taken out, carefully broken down, and every tuber cautiously removed. The greatest care must be taken not to injure the tubers in the operation, as they are extremely brittle and liable to injury. The tubers are then placed in the soil from 2 to 3 inches apart, the strongest in the centre: and in the case of the small pots one tuber will be found quite sufficient. The pots are then filled up with the compost to within 1 inch of the brim (thus leaving room for water), gently pressed, and plunged in a bottom-heat of about 85°, in which quarter they remain until about 4 high, when they are removed to a warm, dry, and light part of the stove near the glass. Until they are well sprung, and the pots getting filled with roots, the greatest care must be taken not to over-water; but afterwards, when they are growing well, water may with advantage be freely given, liquid manure added at least once a-week, and for this I prefer distilled sheep - dung, with the addition of a little guano. They must not even for once suffer through drought, as they never quite recover the check; and I have known it to be the cause of premature ripeness, going to rest without blooming at all.
Each shoot must have a neat stake, to which it is periodically tied out as they grow. Their leaves are also easily injured by a rude touch, and so must be scrupulously guarded, as any injury done to the foliage of a plant materially affects not only its looks but also its vigour, thus injuring it in a twofold manner. They are thus treated until they begin to bloom, which, with the earlier ones, will likely be the end of October or early in November, when they must be transferred to their blooming quarters, there during the dull dreary winter months to be a source of pleasure and gratification to him who has had the pleasing toil of growing them, and a source of admiration to all comers and goers. Where bottom-heat is limited in extent, they could profitably be thickly put into a seed-pan plunged in bottom-heat, and after they are sprung potted off as described above. Neither need those who have no bottom-heat despair, as they will come well on without it, but are vastly the better of it, as it insures a quick and much more vigorous start.