This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Of these the most remarkable is Gloire de Lorraine and its many varieties, which are now grown in hundreds of thousands not only in the British Islands but on the Continent and in America. To M. Lemoine, of Nancy, belongs the honour of raising the original "Gloire de Lorraine" by crossing the South African B. Dregei with B. socotrana from the Isle of Socotra.
The great peculiarity of the progeny of these two species is that the plants, although exceedingly free in flowering, are practically sterile, and cannot be raised from seeds. Gloire de Lorraine and the lovely sports from it, like Mrs. Leopold de Rothischild, Rochfordi, amabilis, are all raised either from leaf cuttings or stem cuttings. This work of propagation is usually carried on from February till July, a fresh batch of cuttings being put in every fortnight to secure a succession. Some growers take shoot cuttings from old cut-down plants about the first week of June, and are of opinion that they produce finer plants than those from cuttings taken in March. The cuttings in all cases are inserted in sandy soil in glass-covered cases, and are shaded from sunshine and kept nicely moistened until well rooted. This generally takes about a fortnight. The plants are then potted up singly in 2½ - in. pots, from which they are later on transferred to 3-in. pots (60's), and afterwards to 5-in. pots (48's) when large enough. Some of the finer plants are moved from 3-in. to 6-in. pots straight away. At the same time old plants left over from the previous year, that have been cut down previously and made break into growth, are repotted into 8-in. and 10-in. pots according to their size. In this way large specimen plants are produced for special purposes.
A slender stake is put to each plant in 5-in. and larger-sized pots, and the shoots are tied up neatly as growth progresses. The soil used consists of turfy loam, sand, and leaf mould in about equal proportions.
It has been remarked that plants of Gloire de Lorraine and its varieties raised from stem or shoot cuttings usually make beautiful pyramidal shapes, while those raised purely from leaf cuttings are more globular in shape and usually more loose in habit. Some kinds, like Mrs. Leopold de Rothschild, appear to break more freely into growth and blossom from leaf cuttings than from stem cuttings, and thus come earlier into the market. Perhaps this variety and Messrs. Rochford's amabilis are two of the very best for market at the present time. One may, however, anticipate new varieties of other shades, and mention may be made of one called "La Patrie", which has large leaves, and rather small but numerous flowers of an extraordinary brick-red colour. One called "The King" is something like the typical Lorraine; while another called "Concurrency" is a Continental sport of some merit.
Messrs. T. Rochford & Sons have also a remarkably free-flowering double form of Lorraine which remains in continuous blossom for six months.
The great advantage of the Lorraine Begonias as market plants is that they are readily raised from cuttings, easily grown during the summer months, flower from October to March and April, and, being so graceful in habit and pleasing in colour, they sell readily.