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.
For a neat, flowering plant in the window, there is nothing which will repay so well for the space occupied, as one or two of the Chinese Primroses. They are natives of China, and are not adapted to out-door culture. They bloom freely under glass, hut unlike the other classes of primroses, require sun, and if properly managed, flower all the year round, although their most flourishing season is during the winter and early spring. All that is necessary for their cultivation is a moderately warm situation, close to the glass, medium moisture, and good drainage, which is secured by filling in the bottom of the pots, with broken pieces of crockery. It is not well to sprinkle the plants with water, as the leaves and flowers will be speckled easily and soon decay. The leaves and flower stalks seldom grow higher than about six inches, and if the plant grows top-heavy, it should be supported by a few little sticks placed near the collar of it. As the plants do not flower so well after the first year, it is therefore advisable to procure young plants every year, or to raise them front seed.
This, however, is not easy; the seeds being very fine, if carelessly watered, or allowed to dry out, they will be lost.
In sowing the seeds, care must be taken to cover them lightly with the soil, or what is better, not to cover them at all, but to press them gently into the surface of the soil with a smooth piece of wood. The watering should be done by saucers placed underneath the pots, or by very fine sprinklers, so as not to wash the soil; but even after the young plants have developed two or three leaves, they require careful watering; if the soil is permitted to get dry, the very tender roots may be dried up in a few hours. Our way of treating the seed is this: We water the lower body of earth in the pot by a saucer, and cover the surface from time to time with a wet cloth, so as to leave the seeds undisturbed.
Of the Chinese Primroses, we have now some most beautiful varieties, double and single; the double white is certainly a beautiful plant, although it does not bloom so continuously as the other. The fringed flowers are considered the very best. - California Horticulturist.