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.
The Columbines are charming border plants, and a good trade is done in the "roots" and also the cut spikes of bloom, especially in the hybrid long-spurred varieties that have been evolved from such species as chrysantha, coerulea, glandulosa, sibirica, Skinneri, and vulgaris. These garden forms have a great range of colour, and the larger the flowers, the longer the "spurs", and the cleaner and clearer the colours the better chance of selling. Muddy or confused coloured varieties are likely to be a drug in the market.
Aquilegias, or Columbines as many prefer to call them, are easily grown in rich and deeply dug garden soil, from 30,000 to 40,000 plants going to an acre. They are easily raised from seeds sown when ripe or in spring in shallow drills, afterwards pricking out the seedlings when about 3 in. high into lines about 6 in. apart, and transplanting the following year at least 1 ft. apart, although 18 in. will not be too much when it is intended to grow the plants for cut flowers only. Particularly good varieties are best increased by division in early autumn, as they are not likely to come true from seeds. The following species and varieties may be noted: A. alpina, 1 ft., deep blue, May; A. atropurpurea, 2-3 ft., deep purple, June; Bertoloni, 1 ft., blue, June; A. chrysantha, 3-4 ft., yellow; A. coerulea, 1-1½ ft., blue and white (fig. 184); A. californica (or A. for-tnosa), 2-3 ft., bright orange-red; A. glandulosa, 1-2 ft., deep blue, and Stuarti, a fine blue-and-white form; A. sibirica, 1-2 ft., bright lilac, with an attractive double variety; A. Skinneri, 2-3 ft., scarlet, yellow, and orange; and A. vulgaris, 1½-3 ft., with blue, purple, or white flowers. There are several double forms in which one or more corollas are placed inside each other.