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.
No gardener who has a demand for decorative plants and cut-flowers throughout the early spring months should be without a good stock of this hardy plant. It is so easily forced, flowers so freely, and the blooms stand so long, either when cut or on the plant, that it is simply invaluable. When a large stock of it is at command, a few plants should be introduced to a warm house, such as a vinery, when forcing commences, and small batches should be introduced in succession, as occasion requires, from January onwards. They luxuriate in a warm, moist atmosphere, with a plentiful supply of water at the roots; indeed it is scarcely possible to injure them with too much water, when growth is fairly started; it is, therefore, good practice to keep the pots standing in saucers or "flats" full of water, giving them weak liquid every alternate watering. Directly the majority of the spikes begin to open their lowermost flowers, the plants should be removed to a cooler and more airy house - they will thereby be better prepared for the dry air of the sitting-rooms, etc, for which they are so extremely well adapted.
When the season is well advanced, the late batches will come on quite well in the greenhouse with sun-heat.
As soon as the earliest batches have finished flowering, they should be grown on in a warm house till about the end of May, when they can be gradually hardened off and planted out in the open border, or shifted into larger-sized pots, and plunged, choosing a warm, sunny position, so that the plants can have all the sun available for the maturing of the crowns. The stock can be increased when desired, by breaking up the largest plants into small bits, and planting them out in rich soil composed of loam and dung in equal parts, in rows 2 feet apart and 18 inches in the row; those in pots should also be plunged in the same compost, and liberally supplied with water, with a little guano or other good fertiliser mixed with it, when dry weather prevails.
As soon as the foliage decays in the autumn, the requisite number of plants should be lifted and potted, and placed in the orchard-house or cold frame - in fact, any outhouse will do where they can be kept cool, moist, and free from frost, so that the plants can be got at when wanted for the forcing-house. Some gardeners are in the habit of potting them as required, but we prefer to get them all under cover in the autumn, about the month of October; and at this potting it is necessary to reduce the balls of those plants which are not in pots, so that pretty large crowns can be easily got into such as 5 or 6 inch pots, which we find most useful for general purposes.