This is usually an active time for this forum (fall too). I just don't feel qualified to answer your question.

How old is your peony? My younger ones often put out more buds than actually open up. Each year the number increases.

Peonies are ALWAYS worth the wait!
Judye

Careful removal of foliage after it dies down in the fall prompt removal of blighted flowers, more sun and better air circulation usually help prevent the loss of blooms due to fungal problems. Peonies are prone to this kind of disease in rainy or humid climates, I think.

Another possibility might be very cold (freezing) temps after some of the buds had gotten to a certain stage were damaged.

I experienced that this spring, with a very late, very cold, very short snap of freezing temps. As a result, most plants had far fewer blooms than normal.

Maybe? Just a thought.....

Sue