Pruning Requirements Of Ornamentals

Press, Volume CVI, Issue 31118, 22 July 1966, Page 6

Pruning Requirements Of Ornamentals

Some emphasis has been placed on the necessity for annual pruning of fruit trees and bushes, when general hints on pruning 'were given. Here are some more specific comments on the pruning requirements of a few of the more widely-grown ornamentals.

Wisterias have a rampant habit of growth, and seem to make an infinitesimal amount of growth during the season. If not properly attended to every year thus soon makes pruning a most formidable undertaking. It is responsive to heavy pruning and can be kept under control, with the result that fltowers are displayed to best advantage. All current growth should be cut back to within two or three inches of the main vine. If this is done annually it will result in the build up of flowering spurs. As the vine ages or as flowering declines a replacement shoot can be selected to develop and then take over from the old one, which should be cut right out Hydrangeas respond to correct annual treatment and soon weaken in growth and flowering if not pruned. Flower buds are carried on either side of one-year-old wood and can be readily identified from wood buds by their plumpness. The best procedure is to commence by cutting out all weak or spindly, dead or otherwise useless growths. Remaining wood should be thinned out depending on the amount of growth made, to leave a bush containing only well spaced strong stems. These can be shortened back to a suitable pair of buds, not as hard cutting back being advocated for plants situated in complete shade as for those growing in the open.

Roses, whether bush, standard or climbing in habit, flower on one-year-old wood and it is a mistake to leave them unpruned for even one year. Their pruning needs are necessary to induce vigorous growth and ample blossom, and to reduce the incidence of disease. Moderately hard pruning is preferable to light or very hard pruning as the former method is inclined to result in earlier flowering which may not suit the exhibitor, whilst the other extreme tends to reduce the number of blooms.

Hybrid tea roses whether grown as bushes or standards should receive much the same treatment, the latter being pruned perhaps a little more severely; the best placed young canes should be retained and pruned back to one third or less of their length usually to on outward-pointing bud.

Climbers require retention of strongest young basal shoots and removal, if possible, of all older wood. Ramblers can be pruned of all spent wood as soon as they have finished flowering and weeping roses can be

treated in much the same way.

Rhododendrons do not need regular pruning, with the exception of the removal of flower heads when they have faded. On young plants the terminals could be removed to encourage dormant buds below to form shoots and create a sturdy bushy habit from near the ground. Old overgrown subjects can withstand severe cutting back into older wood but this should be attempted between September and October at the latest to give as long a growing season as possible. From such treatment dormant buds can be expected to break into growth.

Kerrias respond to cutting out of as much of the old wood as possible to encourage vigorous young shoots. This can be done just as soon as the flowers have faded.

Diervilla could be thinned of old wood every few years after forming a few main branches. Secondary or flowering wood can be cut back each year to within a few buds of the base or to where young shoots are coming away, as soon as flowers fade. This method will induce very good flowering but they will not be as long lived.

The brooms, Cytisus and Genista, are best cut back as soon as the flowers fade but not beyond the base of the previous season’s growth. They rarely survive hard cutting back and in cases of neglect where the p' nts have become extremely leggy it is better to replace them than to bother pruning. Syringa (Lilac)—With the exception of the removal of the old flower heads there is no necessity to prune the garden varieties. However thinning may be required of weak or non flowering bushes. Old, straggly bushes will withstand hard cutting back into old wood if it is desired to rejuvenate them. Pittosporums are more usually grown as hedges rather than specimen trees. As hedges they can be trimmed twice a year to improve their density, and also to avoid cutting back into older wood, to which they are a little sensitive. Specimens can be left to grow naturally or shaped to suit.

Philadelphus should be kept shapely and regularly thinned and old wood gradually removed to encourage new growth. If left they are inclined to become unmanageable thickets.