This section is from the book "The Gardener V3", 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.
This is a most useful plant when properly managed. It makes a fine show all the autumn months. Being of a bright scarlet colour, it mixes well among the Chrysanthemums; and when the spikes are cut, they, like the Gladioli, expand their very last bloom, placed in water in an ordinary room. To have it fine in autumn it should be planted out immediately: all danger from frost is past in rich soil. If it has been grown in large pots the previous season, it should be divided into moderate-sized pieces, as it grows rapidly into large clumps.
In planting, put them rather deep in the ground, pressing the soil firmly all round them, and giving a good watering when finished. If at all a favourable season, they will require very little attention, except an occasional watering with liquid manure; and if long-continued dry weather set in, we find a good mulching of an old Mushroom-bed very beneficial. By the middle of September they will be large plants, beginning to show their flower-spikes; and whenever they make their appearance, no time should be lost in getting them all lifted and potted into pots a little larger than the balls of the plants, filling all round with good rich soil. Care should be taken not to break the ball, nor to injure the roots. After being potted, place them in a pit or frame, where they can be kept close for ten days; give a good watering to settle the soil, and a syringe overhead for a few days, after which they should have plenty of air. When a succession of flowers is wanted, a few may be placed in a temperature of 600, which will soon start them into bloom.
Watering with weak manure-water makes them send up fine strong spikes. "When a quantity of spikes are fairly up and beginning to open, transfer them to the conservatory, where they will stand a long time in bloom; and if strong healthy plants, they will send up several successional crops of spikes. Those that were left in the cold frame will succeed those forced into bloom very well if not allowed to get below 45° at night. We have about twelve large plants in 11-inch pots, on which at one time this autumn we counted sixteen fine spikes, and many more making their appearance: since the middle of December they have been standing under a stage of a Geranium-house, and on looking at them the other day we found them showing signs of beginning to flower again; we shall induce them to do so, by placing them in a vinery just starting. When done flowering, and about May, they will be taken out of their pots and divided, each pot into two, and planted out and treated as above.