My question is about roses in May. Mine have a bit of rust, so I have lightly trimmed the bushes. Does that matter so close to winter? What is the best time to prune in Christchurch?
Wait until your rose bushes are completely dormant e.g when all the leaves have fallen from the plant before carrying out the annual pruning. If you prune before the plants have become dormant there is always the chance of new growth appearing soon after the pruning is completed. This growth that will come to nothing e.g. no flowers when winter sets in.
While rust can be disconcerting on the leaves of your roses, it’s preferable not to lightly prune your plants at this time. Remember to collect all fallen rose leaves and remove from the rose garden to lessen the possibility of reinfection next spring.
A cleanup spray of copper oxychloride and or lime sulphur applied after winter pruning will help reduce the impact of any overwintering black spot and rust.