Well a photograph speaks a thousand words, but without one, either insufficient water at the root causing the plant to sacrifice its flowers, or lots of rain causing fungal problems on the buds and preventing the flowers completing their cycle. Or mildew problems.

Hi, I agree with Bamboo, if you've had cool wet weather, and then sunshine it could be what's known as bud balling, the outer petals get saturated, then the sun comes out, and the drying causes all the petals to fuse together, which prevents the flower from opening, this also applies to Peonies and Camellias, Derek.