Cool climate gardeners can prune their roses from August on. Bearing in mind that pruning stimulates growth, should you have pruned too early, any young shoots may well be hit by a late frost. Depending how far back you pruned initially, there may be little more to cut.
So why do we need to prune roses on an annual basis? Primilarly because modern hybrid tea roses, floribundas and carpet roses produce their best bloom on new season’s wood. Unpruned plants will continue to bear but carry small flowers on taller and taller growth.
By cutting away old woody stems and other unproductive shoots, together with a helping of fertiliser plus mulch, we can stimulate new growth with bigger and better blooms at a level that makes them easier to admire and cut for the vase.
Not all roses are cut to the same shape, but usually for the same reasons: the removal of old, diseased and dead growth, plus any over-crowded central mid-shrub growth which restricts the airflow and light.
Once the basic shape has emerged (four or five branches similar to an upturned umbrella), branches in excess should be cut back by half, depending upon the ‘eyes’ along the stem. Select a bud that faces in an outwards direction and make a cut with clear sharp secateurs slightly above – cut too close you may damage valuable tissue; cut too far away and you will leave a stub that will eventually die off.
The pruning of ’standard’ roses (hybid tea roses grafted onto one metre or 1.5m standards) are pruned exactly as you would the roses set at ground level.
Climbing roses are shrubs unto themselves. They are not usually pruned for the first couple of years allowing a good framework to be established. The best blooms are produced on the laterals that emerge from two to three year old wood plus the training or tying in of these laterals in a horizontal position, or perhaps slightly upright.
Climbers that are not pruned in winter include the spring flowering banksia rose and wichuriana, which should only be pruned back once flowering is over.