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.
A splendid family of climbers and dwarf trees. It is the representative genus of the order Bignoniaceae, which furnishes so considerable a portion of the gorgeous colouring for which the tropical forests, those especially of South America, are famous. The majority of the species of Bignonia are tropical, and therefore not adapted to culture in an atmosphere cooler than a warm greenhouse. The difficulty is to get the wood well ripened in a low temperature. If that can be done, the plants will bear a greenhouse temperature in winter without injury, and will flower freely the following summer. One or two species - B. radicans, grandiflora, and capreolata - are hardy enough to grow well in any part of Britain against a wall; but it is only in warm places in the south that their flowers are enjoyed in all their splendour. The three species just named succeed well, however, in a cool greenhouse - admirably where the climate is not favourable to the development of their flowers in the open air. They make beautiful pillar and rafter ornaments, and splendid covering for walls, where they may have ample space to ramble; for, being great growers, they want plenty of room. Of B. radicans there are two varieties, named minor and major.
The former is the brightest coloured, being a fine orange scarlet; the colour of grandillora is orange, and capreolata is scarlet, - and they all produce their flowers in summer. Other sorts which succeed well in the greenhouse, being nearly hardy, are B. capensis and B. jasminoides, both of which are not uncommonly named Tecoma instead of Bignonia, - a synonym which is founded on a distinction in the fruit of the two so-called genera, and which may be of some importance to botanists, but is of no consequence to gardeners in any practical sense; so that in the garden at least we may dispense with the name Tecoma, and reduce by one the chances of confusion and disorder. In the south, where the summer is longer and warmer, the following kinds may be tried in the greenhouse with good prospects of success, if the other conditions of management are good: B. crucigera, yellow and scarlet; B. Tweediana, yellow; B. venusta, orange scarlet; and B. diversifolia, purple and white. They are plants of the easiest culture.
Strong, vigorous growers, they do not succeed well in pots, but prefer being planted out in good fibrous sandy loam; and they should be thoroughly drained - a point which, if carefully attended to, will conduce very materially to the successful culture of the tropical species in cool houses. They should be allowed to cover the space they are intended to occupy as soon as possible. The flowers are produced on the shoots of the current season from well-ripened buds of last year's formation, after the manner of the Vine. This suggests that in the matter of pruning they should be treated in the same way - not, however, on the short-spur system, but by cutting back last year's shoots in winter or spring to joints that are thoroughly ripened and have prominent buds. They may be propagated by cuttings of the fully-ripened shoots put into bottom-heat in spring, or by short-jointed, partially-ripened shoots in summer in heat under a bell-glass. Some kinds also, perhaps all, may be easily propagated by cuttings of the roots - the strongest roots being cut into short lengths and planted rather thickly in pans in sandy soil, or in sand in a propagating-bed in bottom-heat.