Question
I have a big healthy looking red rose bush the flowers get huge but are turning brown before opening. What would cause that?

Answer
When a rose bush looks healthy but the flowers don't then it may be an insect that is causing the problem. Take a piece of paper and hit the buds over it and see if there are any small bugs showing. If there are then there is a small fly like insect called a midge which lays it's eggs at the base of the flower buds. When the larvae hatch they feed on the rose bud. Thy are very very tiny but they still do enough damage that the flower will be damaged. Any rose insecticide will solve your problem. When you use the spray pay special attention to all the buds as that is where the midge will be. The other reason could be botritis. This is when the weather is warm and then cold at night, so it partially rots the flowers before they open. There is nothing you can do about it and when the weather returns to being constantly warm, the problem will go away. Hope this helps.