Pruning in summer, when the plant is in active growth, has an effect contrary to that of pruning when it is in a dormant state. Far from increasing its vigor, it weakens it, by depriving it of a portion of its leaves, which are at once its stomach and its lungs. Only two kinds of summer pruning can be recommended. The first consists in the removal of small branches which crowd their neighbors, and interfere with them: the second is confined to the various classes of Perpetual roses, and consists merely in cutting off the faded flowers, together with the shoots on which they grow, to within three or four buds of the main stem. This greatly favors their tendency to bloom again later in the summer.
When old wood is cut away, it should be done cleanly, without leaving a protruding stump. A small saw will sometimes be required for this purpose; though in most cases a knife, or, what is more convenient, a pair of sharp pruning-shears, will be all that the operator requires.
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When roses are trained to cover walls, trellises, arches, or pillars, the main stems are encouraged to a strong growth. These form the permanent wood; while the side-shoots, more or less pruned back, furnish the flowers. For arbors, walls, or very tall pillars, the strongest growers are most suitable, such as the Prairie, Boursault, and Ayrshire roses. Enrich the soil strongly, and dig deep and widely. Choose a healthy young rose, and, in planting, cut off all the stems close to the earth. During the season, it will make a number of strong young shoots. In the following spring cut out half of them, leaving the strongest, which are to be secured against the wall, or over the arbor, diverging like a fan or otherwise, as fancy may suggest. The subsequent pruning is designed chiefly to regulate the growth of the rose, encouraging the progress of the long leading shoots until they have reached the required height, and removing side-shoots where they are too thick. Where a vacant space occurs, a strong neighboring shoot may be pruned back in spring to a single eye. This will stimulate it to a vigorous growth, producing a stem which will serve to fill the gap. Of the young shoots, which, more or less, will rise every season from the root, the greater part should be cut away, reserving two or three to take the place of the old original stems when these become weak by age. When these climbing roses are used for pillars, they may either be trained vertically, or wound in a spiral form around the supporting column.
Roses of more moderate growth are often trained to poles or small pillars from six to twelve feet high. Some of the Hybrid China roses are, as before mentioned, well adapted to this use; and even some of the most vigorous Moss roses, such as Princess Adelaide, may be so trained. Where a pole is used, two stems are sufficient. These should be examined, and cut back to the first strong and plump bud, removing the weaker buds always found towards the extremity of a stem. Then let the stems so pruned lie flat on the earth till the buds break into leaf, after which they are to be tied to the pole. If they were tied up immediately, the sap, obeying its natural tendency, would flow upward, expanding the highest bud, and leaving many of those below dormant, so that a portion of the stem would be bare. (The same course of proceeding may be followed with equal advantage in the case of wall and trellis roses.) The highest bud now throws up a strong leading shoot, while the stem below becomes furnished with an abundance of small side-shoots. In the following spring, the leading shoot is to be pruned back to the first strong bud, and the treatment of the previous year repeated. By pursuing this process, the pillar may, in the course of two or three years, be enveloped from the ground to the summit with a mass of leaves and blossoms.
These and all other rose-pruning operations are, in the Northern States, best effected in March, or the end of February; since roses pruned in autumn are apt to be severely injured and sometimes killed by the severity of our winters.
