This section is from the book "The Gardener V1", by William Thomson. Also available from Amazon: The New Organic Grower: A Master's Manual of Tools and Techniques for the Home and Market Gardener.
Taking the numbers in cultivation into consideration, this is the most popular of all classes of Roses; and we are glad to learn that those ugly standards with long stems and tufts of heads are fast giving place to the more useful dwarfs. Before beginning to prune, it should be taken into consideration, that according to the time of pruning, so will the blooms come. If all the Roses are pruned on one day or in one week, then most of them will come into flower together. Supposing a portion of the stock were pruned on the last days of February, a few more about the middle of March, and the last about the beginning of April, a much longer succession of blooms would be had during June, July, and August, than by pruning the whole of them at any of these times. Season and climate must also be taken into account, as some may be able to prune their Roses days or weeks before others; but from the end of February to the beginning of April will include all Roses and latitudes. Some kinds of Hybrid Perpetuals grow very strong, others weak. This is not always owing to cultivation, but often to constitution. Shy growers are not the best for ordinary cultivators. Those of the Paul Neron type are the kind. As their growth so must the pruning be. Strong growers will always bear hard cutting.
The more wood they have formed, the more must be taken out. The strongest shoots should be cut in to three or four buds from the base; all the weak shoots should be cut close off to where they have started, not leaving a bud to form another shoot, as it is such as these that produce a number of small flowerless stems only to crowd up and smother the others. Weak-growing varieties must be done in the same way, but one or two more buds may be left on each stem. When the plants are two or three years old, it takes some care to prevent the dwarfs from assuming a semi-standard form, as by a loose way of pruning the stems sometimes become some feet in length, with a number of smaller growths emitting from the top. To rectify this, the best plan is to cut such stems down to a few inches from the ground, and let them sprout afresh.