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.
A genus of rock and border plants requiring a mixture of sandy loam and peat or leaf mould, and best increased from seeds. The best kinds are: anthericoides, 9 in., slaty blue; comosum, 3-6 in., blue; Sheuchzeri, 1 ft., deep-blue round heads; spicatum, 1-3 ft., with white, cream, and blue varieties. The flowering period is from June to August.