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.
Magnificent herbaceous perennials with thick fleshy roots, long sword-like leaves, and immense spikes of starry flowers often towering 8 or 10 ft. above the soil. They like a well-drained loamy soil in warm sheltered spots or in thin shrubberies. The rootstocks sell fairly well, but it is necessary to make the plants better known. One of the best-selling kinds is E. robustus, with pale-pink or rosy flowers, and its fine variety Elwesianus, with flesh-coloured flowers. Other excellent kinds are Bungei, 1-3 ft., bright yellow; aurantiacus, 3 ft., pale yellow; himalaicus, 3-10 ft., white; Olgoe, 2-8 ft., lilac white; wurei, coppery yellow; and turkestanicus, 4-8 ft., red with white edges. They are all natives of Afghanistan, Persia, Turkestan, etc. They may be propagated by careful division in early spring, and also by seeds. The seedlings reach the flowering stage about the third year. There are several fine hybrid forms.