This section is from the book "The Gardener V2", 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.
The probability is, that the seed you have procured of the Lassianthus Russelliana is too old. It, however, may yet vegetate. Cover the top of the pot with a sheet of glass, and keep it in a moist stove or dung-frame. The compost you have used is perfectly suitable. When the plants come up, inure them to light and air gradually. Let them grow in the seed-pot till they have four leaves, then prick them off into a pan, in compost of equal parts light-yellow loam, peat, leaf-mould, and silver-sand, and shade for a time, paying attention to watering. When they are, say, such plants as a shilling will just cover, pot them singly in 60's, keep them still in a warm frame, then into 48's, and harden them off by degrees, till in September they can be placed on a dry shelf in the greenhouse, where they may stand till March. See that their foliage never gets wet, else they will drop off at the neck. In March, place them in a dung-frame with mild genial heat. When they start into growth, both above and below ground, shift them, still in the same compost; and when fit shift again, till they are in 8 or 9 inch pots, where they should flower well in a stove.
By such treatment we have, thirty years ago, grown plants with 300 blooms on them, and as freely as Balsams. There is no plant more deserving of cultivation; yet it is nearly out of cultivation.