This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Pot-grown Roses for market represent but one phase of the subject, and thousands of long-stemmed Roses result from planted-out specimens. These, however, cannot be started into growth so early as pot-grown plants, and are best when given a much slower treatment from the start. This applies to the Hybrid Perpetual class more particularly, and always to those in beds at ground level, as opposed to those on raised beds or benches receiving the benefits of the applied heat.