Question
I'm a county agent in PA and routinely field hort questions even though I'm a foods and nutrition person. I got a call from a woman who has a collection of old roses and a variety she has is plagued with something that dries and shrivels the outer ring of petals of each rose so that the bloom cannot open. She says if she hand-removes the damaged outer petals, the bloom will continue to open properly. What could cause this and what can she do?

County Agent in PA

Answer
The older garden roses usually have a lot of very thin frail petals. If the weather is very hot or humid when they start to open, the other petals can't take the heat and dry out. If it is humid, again the other petal get too much moisture in them and so they stick like glue and dry out. This usually occurs with the old Moss roses especially if they are young plants however once they become mature the problem usually lessens. Because one can't control the weather it can become a real annoyance. If it is a Moss roses that is giving her the problem or for that matter any other, if she makes sure that the rose bush gets extra amounts of water when it is starting to open that will help the flowers to produce firmer petals. But as I said, if the weather is damp or hot the problem will return. It is not an unusual problem and most gardeners who grow the older roses are aware of it and as she said there are some that seem to be worst than others.