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.
This fine old climber - one of the best and most showy we have - is not so often met with as its merits deserve. It is a tuberous-rooted plant which dies down every autumn. When it has been strongly grown, the tubers are forked, and about 6 to 10 inches in length. When at rest, the tubers should be shaken out of the mould, and stored in pots of dry sand, and kept dry and warm during the winter months. I generally place them under the first shelf of the stove, a little distance from the hot-water pipe, and standing on an inverted flower-pot to prevent damp from rising to them. In early spring they are potted, and in doing so the tubers are reversed or turned upside down every year, because the young tubers with roots and stems are formed not from the crown where the previous year's stems spring from, but from the opposite end. The young tubers exhaust the parent, which dies every year.
The soil used is a rich fibrous loam, with vegetable mould and sand or grit blended or mixed together. After potting they do best if plunged in bottom-heat, without which they take a long time to start into growth. They require but little water till fairly started. As the growths increase the water is increased; and when in flower, a liberal supply is necessary; and being a rank feeder, occasional waterings with manure-water are beneficial.
As soon as the plants grow and root sufficiently to require a shift, they are put into their blooming-pots and subjected to a more moderate degree of heat, air, and moisture, and not over-much shade, which weakens them. They throw up one stem from each point of the tuber, from 5 to 8 feet or more in height, and form a branching head, or rather a panicle of flowers, and continuing to yield flower after flower for many months in succession, each bloom remaining a good while in perfection, and resembling the Turk Cap Lily, each petal being-beautifully twisted and crisped. At first they are a rich orange-and-scarlet, changing to crimson before they fade.
This Gloriosa is a plant I would recommend for exhibitions, of which the cry is heard that they do not bring together much variety from year to year. This plant would not only be a rarity at shows, but could not fail to attract attention. It would form an excellent companion for Stephanotis floribunda, the Allamandas and Dipla-denias. In order to make fine specimens, many tubers should be put into a pot; and, if required early, they may be potted in autumn, using rich soil, and in other respects managed as already directed. Each stem should have a stake, and be frequently tied, as they should not be allowed to get entangled the one with the other, for at the end of each leaf they are furnished with a tendril which clasps everything it comes into contact with. When the flower-buds appear, the stems should be all untied and carefully supported round the pot, while a suitable trellis is being fixed to the pot in training, to which great care is necessary, as the growths are brittle. In training or tying the shoots to the trellis, the flowers should be arranged so as to make the plant as well furnished and conspicuous with them as possible when they are in bloom. The panicles themselves should not be trained.
When in bloom, and particularly if in not very large pots, the supply of water and stimulants must be constantly attended to with care.
When the plants are done blooming, and showing signs of going to rest, gradually withhold water, and cease to give any when the stems decay. When dried off, store them away as already described. The time at which they are required to bloom must regulate the starting-time. For early flowering they should be started in autumn, and a succession can be kept up till late in autumn by starting a few tubers in succession till late in spring. Altogether this is a much-neglected plant, and worthy of much more countenance than it receives. A. B. T.