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 hybrid Pentstemon of to-day had their origin in P. Hartwegii or P. gentianoides and P. Cobcea, both natives of North America. They are plants of great garden value and ornament - valuable because of their colour warmth and for their late summer and autumn flowering. To florists generally, and to northern florists in particular, we are indebted for the high-class strains which now obtain, the crimsons, scarlets, and reds generally being most effective in late summer. As the plants do not possess the attribute of complete hardiness, they must be raised from seeds or cuttings. Sow the seeds in January or February in the greenhouse, subsequently pricking the seedlings off and later potting them singly into small pots prior to planting in open ground in May. Grown quickly, such plants flower profusely during their first year. Cuttings may be inserted in sandy soil in slight warmth in autumn or spring, the former giving excellent plants for stock purposes or for bedding out. Grown commercially, both seedlings and cutting-raised plants afford a good business line, the best named varieties realizing good prices. The plants succeed quite well in garden soils that have been well tilled, and those of a light and warm nature for preference (fig. 234). [e. h. j].
Fig. 234. - Garden Pentstemon.