My roses flowered brilliantly during the warm, dry weather earlier this summer, but now they are miserable and a lot of the flowers are dying off without even opening. Any suggestions as to how I can help them to recover? M Murphy, Cork
Roses generally flower best when growing in a warm, bright, open but relatively sheltered spot where they can enjoy a deep, fertile soil enriched with mulches of well-rotted manure and a few handfuls of organic, slow-release pelleted fertiliser. The cool, rainy weather of late hasn’t been kind to them, damaging and disfiguring petals and creating the kinds of growing conditions conducive to the spread of a range of common fungal diseases such as rust and black spot. Wet weather also causes a condition known as flower-balling, where the outer petals get so wet that they form a leathery skin around the bud, preventing the flowers from opening properly. This is often followed by the appearance of grey mould on the afflicted buds.
From your description, it sounds likely that this is what’s affecting your plants. There’s no cure for it as such, but the good news is that it’s typically a temporary problem that will resolve itself when the weather improves. In the meantime, the best solution is to rigorously deadhead all affected flowers to encourage the production of new healthy flower buds, and give plants a fortnightly liquid feed.
To reduce the chances of this happening in the future, try to encourage an open growth habit through careful pruning techniques and avoid growing other plants too closely around them. Also bear in mind that certain varieties of rose, typically older kinds, are more vulnerable to this problem.
