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.
Out of some 450 species of Sage there are only two or three species largely grown for decorative work. S. splendens is a Brazilian plant, 2-3 ft. high, remarkable for its brilliant scarlet flowers, which are produced in abundance. There are several fine varieties of it, easily raised from cuttings in sandy soil in spring, and plunged in a hotbed till rooted; or many of them may be raised from seeds sown at the same period. Some of the best forms are grandiflora, Glory of Stuttgart, and Glory of Zurich - the latter being perhaps the best and most popular for bedding-out work. It is a magnificent plant of bushy habit, and produces its flaming scarlet blossoms in profusion during the summer months. A new yellow-flowered variety has recently appeared, and has yet to make its way. Other scarlet-flowered Sages are coccinea, elegans, fulgens, gesneroefolia, Heeri, involucrate Bethelli, rutilans, etc, all of which require the same treatment as S. splendens.
Amongst the best blue-flowered Salvias are S. azurea, 3-6 ft. high, and S. patens, 2-3 ft. high, both very deep in colour, but with flowers more loosely borne than in the scarlet forms.