This section is from the book "A Dictionary Of Modern Gardening", by George William Johnson, David Landreth. Also available from Amazon: The Winter Harvest Handbook: Year Round Vegetable Production Using Deep Organic Techniques and Unheated Greenhouses.
Of this hardy herbaceous flower there are forty-one species, but the following is a good selection: -
P. argutus, purple. P. atropurpÚreus, brownish purple. P. campanulatus, rosy red. P. crassifolius, deep lilac. P. diffusus, deep blue. P. gentianoides, brownish purple. P. gent, coccineus, scarlet. P. glandulosus, deep blue.
P. latifolius, white, slightly stained with purple. P. Mackayanus, purple and white. P. Murrayanus, bright scarlet. P. ovatus, bright blue. P. procerus, bright blue. P. pulchellus, light blue. P. Scouleri, lilac. P. speciosus, bright blue. P. venustus, light purple.
A light rich loam, mixed with peat. They may be increased by division, but the strongest plants are raised from seed.
Sow in October, or until January, in a cool frame. Keep the plants near the glass until strong enough for planting out in late spring. Always save seed when you can, and keep a stock of young plants to supply vacancies.
 
Continue to: