Spring is now unfolding with all the blossom trees, prunus, pear and cherry transforming the winter landscape and heralding the spring roses. Our plants were growing away strongly in the warm weather and will begin blooming about the middle of October. The Hybrid Teas will flower slightly earlier than the Floribundas and it is important to keep new shoots free from mildew and black spot. If plants defoliate, growth is hampered and sunburn can occur.
Mildew and black spot can be prevented by regular sprays of triforine or mancozeb. When the weather pattern has settled and warm dry air dominates, fungicide spraying can cease and not resume until autumn. The aphids should be controlled with insecticide when they build up and threaten the vigour of new shoots.
Flowers should be picked in the cool of the morning or evening, cutting the stems to an outward pointing bud if possible. Place them up to their necks in a bucket of water so that they will be conditioned before arranging or sharing. If this is done then the life of the cut bloom is greatly extended. The first flush of bloom will greatly decrease and finish in late October or early November. This of course will vary with your locality. Spent bloom should be removed taking the flowers on a short stem, about 150 mm. New growth will then be produced and flowers will be back on the bushes around Christmas.
During the hotter days, late November and through summer, plants must be kept moist to produce flowers. A deep weekly soaking will ensure this. Good results can be achieved with tube and drippers set under the bushes. This method of watering has advantages as the foliage is not dampened and therefore mildew and black spot are not encouraged and water is not wasted through inefficient sprinklers.
Bush roses which were planted in winter should have flowered for the first time in October and a quick inspection will enable you to check if each plant is true to its name. New strong basal growth will begin to appear in early December and these shoots should be staked and tied to protect them in high wind. Light feeding with ‘Sudden Impact’ can now be done. Newly planted climbing roses will flower and then produce climbing canes which must be tied vertically to a trellis or post to prevent loss, as these shoots will bear next year’s bloom. It is important to tie shoots vertically as sap rises to the highest point where growth is strong and vigorous.
The surface soil should be mulched and pea straw or lucerne straw are probably the best. I use pea straw and we apply it to our garden before the new growth is too long (under 50 mm) to prevent damage to the shoots while spreading. In our garden the process is done in two stages. Firstly, we biscuit the straw out in 100 mm slices and leave until it is softened by rain, then go back after the rain and spread by hand or with a fork. This way the dust is not such a problem and the biscuits of straw break up easily.
By Walter Duncan