[From The Practical Book of Outdoor Rose Growing, by George C. Thomas, Jr., p. 17... quoting from Pemberton:] Many of the species... together with Provence and Damask hybrids, etc., increase by throwing out suckers, springing up at some distance from the parent plant, and forming roots at the place where they bend upwards. These roots suckers, after being separated from the plant, should be pruned back to a foot or even less, and then treated as ordinary plants.