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 the 160 species known, the only one grown in great quantity for market is the Common London Pride or St. Patrick's Cabbage "S. umbrosa), really a native of the Kerry mountains and the Spanish Peninsula. It has rosettes of spoon-shaped coarsely toothed leaves, and throws up clammy clusters of beautiful white flowers, dotted with pink in early summer, in great profusion. The plants flourish anywhere in shade or sunshine in any garden soil, and produce offsets with remarkable freedom. There is therefore no trouble in keeping up the stock. The young offsets should be taken off in August or September - earlier or later according to circumstances - and dibbled about 4 in. apart in beds 4 to 5 ft. wide. In this way over 300,000 plants can be got to an acre, allowing for pathways, and if they realize only a farthing each, the receipts are over £300 per acre. Unfortunately anyone can grow London Pride, therefore it would be unwise to overstock it. Amongst nurserymen a very good trade is done with the "mossy" and "encrusted" species of Saxifrages, as well as with the large-leaved or " Megasea" section. They are charming plants for rock gardens and borders; while one large-leaved species, S. peltata, the Umbrella Plant, with leaves often 18 in. across, is a first-rate plant for the sides of lakes, streams, pools, etc. The reader interested in these species would do well to consult the Practical Guide to Garden Plants (J. Weathers), which contains full descriptions of most species with cultural details.
One other species is sometimes found grown in quantity for market, viz. S. sarmentosa, known under such popular names as Aaron's Beard, Creeping Sailor, Mother of Thousands, Wandering Jew, Pedlar's Basket, and doubtless many others. It is a Chinese plant, with roundish, hairy, roundly toothed leaves, mottled above, red beneath, and has white flowers spotted with yellow and red. Numerous young plants are produced at the end of creeping stems. The plants flourish in any garden soil, and are generally grown in hanging pots or baskets. The variety tricolor has the leaves blotched with green, white, and red, but is more tender than the common variety. Both can, however, be grown in a cool greenhouse or frame, and are increased by the offsets.
The following is a good selection of "cushion", "mossy", and "encrusted" Saxifrages: -
All white flowered, except where otherwise stated; apiculata (yellow) (fig. 242), Burseriana, crenata, coesia, coesia-phylla, Elizabethoe (yellow), Ferdinandi-Coburgi (yellow), Frederici-Augusti (pink), juniperifolia (yellow), marginata, Patraschi, Rocheliana, sancta (yellow), Salamoni, tyrolensis, valdensis.
All white flowered, except where otherwise stated: anceps, aquatica, Arkwrighti, caespitosa, Clibrani, decipiens (red), and varieties Bakeri, cruenta, Bathoniensis; densa, geranioides, Guildford Seedling (crimson), Haworthi, hirta, hypnoides, Iratiana, Lindsayi, Maweana, muscoides and its variety purpurea (purple), palmata, pede-montana, Rhei, Stansfieldi, tenella, trifurcata, Wallacei, Willkommi.
Fig. 242. - Saxifraga apiculata,.
All white flowered, except where otherwise stated: Aizoon, with pink and yellow varieties (rosea and lutea) ambigua, Boydi (yellow), with a white variety; aretioides (yellow), Camposi, carin-thiaca, cartilaginea, cochlearis, Cotyledon, crustata, diapensioides, Hosti, Kolenatiana, lantoscana, lingulata, longifolia, Macnabiana and variety alba; nepalensis, notata, pectinata, pyrenaica, rho3tica, scardica, Vandelli.