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.
Owing to the difficulty that is generally experienced in cultivating the Gentians, they are found only in few gardens, where a delight is taken in overcoming cultural obstacles. The trade in the plant is naturally very restricted, but the brilliant blue of the flowers will always induce a few to invest. The best blue kinds are acaulis (fig. 202) and verna, each about 3 in. high, with masses of blue bell-shaped flowers overtopping the leaves. They are most likely to succeed in well-drained gritty soil composed of loam, peat, and sand in cool moist positions in the rock garden. Such kinds as asclepiadea, 1½ ft.; cruciata, 9 in.; Pneu-monanthe, 9 in.; and septemfida, 1 ft., all with blue flowers, are fairly easy to grow; while 0. lutea, 3 ft., with yellow flowers, is the most vigorous of all.
Fig. 202. - Gentiana acaulis.