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.
I should be obliged by some information respecting the proper mode of cultivating Violets for winter bloom, in hot-beds; what time they should be planted in the beds to secure an early and constant bloom during the winter; the proper kind of soil they require; and whether, for the second planting the new shoots should be separated from the old, and the new only planted; and if so, at what time this separation should be made. I have tried them for two years without much success. The plants look healthy enough, but have shown very little bloom, and that very late. Subscriber.
To prepare plants for winter forcing, the young side shoots be taken off in April, and planted in a bed of prepared soil - say equal parts of leaf mold, sand, and good garden loam, with a slight admixture of well rotted cold manure. Shade from the mid-day sun, and water occasionally overhead with a fine rose. Here the plants will soon get well rooted, and may be transplanted into another bed to prepare them for potting or frames where they are to bloom, This bed should be prepared as above, and the plants should be set in rows two inches apart and six inches in the rows. Give them plenty of space, so that they will not get drawn up andw eakened; for in this state they will not bloom freely or strongly. All runners should be kept down, and the soil moved frequently, and an occasionally overhead watering be given - protect also from mid-day sun, as they cannot bear this. About the latter end of August, or first of September, the plants may be lifted from the bed, with balls, and potted or placed in frames. The earth used in potting should be something like that shore described, and the pots should be well drained. Lay in a handful of broken crocks in each pot, and a little moss over them, to keep the earth from mixing. They can not bear stagnant moisture.
After potting, they should be set on a bed of gravel or cool rubbish, and be very carefully watered, and shaded from the hot sun. As soon as flowers are wanted, they should be placed in a slight bottom heat under glass, have the benefit of air frequently, and a moist atmosphere. Here they will give plenty of flowers. If placed in a box or frame, they should be within six inches of the glass. Air should be admitted as often as can be done safely, and water supplied to keep a regular but not superfluous moisture. The frame should be well protected on cold nights with thick straw mats, and the frame should be lined all around with manure or manure and leaves. Here flowers might be had till Christmas; but our severe northern winters rendering it unsafe to open a frame or admit air for weeks together, preclude the possibility of gathering flowers from such a frame in the depth of winter.