Why Prune Roses?
Why We Prune
Theof presents a deal of difficulty to some, but if it is realized that the main object is simply to aid the natural habit of the plant by cutting away weakly and decayed wood, it will perhaps lose some of its complexity. To illustrate this point, as all will have observed, a rose-tree does not grow telescopically; in other words, it does not send out, say 18 inches of growth this year, and the stems carry on extending the following year for another 18 inches. What happens is, in the spring the tree breaks into growth, and in a matter of from 10 to 17 weeks, according to the nature of the variety, the individual stems have reached their limit of growth and then flower. Almost immediately new growths break out from lower down these particular stems, and in their turn, after flowering, they possibly send out further new growths. From this it is obvious that in each instance the new growths must be taking some of the nourishment which would otherwise go to the older ones, with the result that the latter owing to starvation have a tendency to die back. It does not necessarily follow that this will happen immediately, but it is ultimately inevitable. The object of pruning is to aid the tree by cutting away those upper portions of the stems which, having fulfilled their purpose, are no longer required, thus diverting nutriment otherwise wasted to the formation of new, sturdy growth.
The same principle applies to the cutting away of unripe or damaged wood, which takes away nourishment required by the healthy parts of the tree and is, therefore, best dispensed with. Unripeness can be due to a number of causes, but damp, sunless weather in the autumn is possibly the most common reason. Over-feeding through the wrongful application of nitrogenous manure late in the year and the effects of premature defoliation due to disease are further causes.
Testing for Ripeness
At the time of pruning, to ascertain whether the wood is ripe or not, pinch it hard between the finger and thumb, and if it gives it is soft and no good. Another method is to press the prickles on the stem gently with the thumb. If the wood is ripe they will fly off, but if not they will bend and only break off with great difficulty. One further guide is that the pith of unripe or damaged wood is discoloured. It should be a greeny white, not yellowish or brown.
When to Prune
What is the best time to prune? There is considerable controversy on this point, some arguing that it can be done as early as December, while others advocate March. Faults to be found with December pruning are, firstly, that in most instances it becomes simply the shortening of the long stems and is, therefore, more in the nature of a tidying up than an actual pruning operation; secondly, the trees carry into the next season new growths made during a spell of mild weather during the winter months, together with prematurely formed foliage. Such foliage is almost certain to be undersized owing to its appearance before the sap is flowing strongly, and damaged as well, as it is rare that the winter ends without a final burst of bad weather. Consequently the trees are inclined to shed their leaves in early summer, thus possibly contributing to attacks from disease. One more point, December pruning, for the foregoing reasons, conflicts with the axiom so often quoted that the trees in the spring should always be cut to a dormant eye.
Now for the other side of the argument. Spring pruning cannot in any way protect the new shoots from the action of late frosts, therefore those in favour of early pruning have a point in their favour. Another risk of March pruning is that in an early season roses pruned at this time are likely to bleed and the trees thus debilitated from loss of sap.
It would seem that weighing all things in the balance, it is best to prune some time towards the end of February. This will be early enough to prune to a dormant eye, also it will avoid the risk of bleeding and yet be late enough to see the effects of the winter on the wood. Although February pruning cannot eliminate the risk of subsequent damage, it will at least restrict it to these late periods. The trees will not start off carrying a number of shoots certain to have been damaged by frost.
To Prune Hard or Lightly?
Whether to prune hard or lightly is another question which is often put. Bearing in mind what has been said about the object of pruning, this point largely answers itself. There is no purpose in pruning harder than is warranted. Each tree should be judged on its merits, and the individual stems pruned according to their condition, keeping in mind, however, the general appearance of the tree. Aim to obtain a shapely bush and, whenever possible, prune to an outward pointing eye. The cut itself should be made approximately -1/2 inch above the eye with a gentle slant in the direction in which it is pointing.
The foregoing has dealt with pruning in a general sense, but with strong-growing bushes as, for example, the species Hybrid Musks and those of the Floribunda type, a little licence is permissible, so as to make them flower all the way up and not simply at the top. The way to do this is to retain some of the sturdy stems almost full length, but purposely reduce others to half their length, while yet others should be pruned even lower. This is in no way departing from the general principles advocated, as only the sound, ripe, undamaged growths would be retained full length, those shortened being respectively in their second and third years of growth.
The pruning of these trees differs in principle in no way from that of their bush counterparts. Retain as much as possible of all good, sound wood, and cut away all weakly, old and damaged growth.
Ramblers and Climbers
Broadly speaking, these come into two categories, those that throw up a number of supple growths from the base each year, ie. the Wichuraiana ramblers, and those which do not so freely produce new basal growths, the Wichuraiana climbers, large-flowered climbers and climbing Hybrid Teas. The growths of the latter are usually thick and sturdy, and for this reason are easily distinguishable from the other type. The varieties which produce a large number of supple growths are summer flowering only, and the time to prune them is in September. All the old growths should be cut clean away from the base to make room for the new.
The other type requires little pruning of the main stems beyond thinning them out every now and again by removing the oldest shoots. If it is found that new, vigorous growths have started out from various points along the old stem, prune away as much of the old stem as possible, although at times if the plant is getting overcrowded it is necessary to sacrifice these new growths and remove the old stem entirely. In this second type we get both perpetual flowering varieties, such as the climbing forms of the bush roses, and also varieties that flower but once. However, the foregoing remarks apply to each. The pruning of these should be done in February, and beyond the thinning out referred to nothing more is required beyond the removal of wood that has died back and the shortening of the lateral growths. For pruning purposes, in the list, the first type, ie. those that throw from the base each year a number of supple shoots, have been indicated by Prune ‘A’, and the second type by Prune ‘B’.