Old-fashioned peonies are among my favorite perennials, easy to grow, spectacular in flower and awesomely fragrant. The old fully double varieties, however, have a serious weakness: a single rain storm while they are in bloom will completely trash them. The flowers will fill with water until they weigh a couple pounds each and crash to the ground. No amount of staking or support helps much. (Some examples from around the web: Georgia, Michigan, and Illinois.)
The newer single, semi-double, and anemone-flowered peonies are better in this regard. The less congested petals of these types let the rain water drain out, so these flop much less. Unfortunately, in experience, they are also either completely scentless or only very lightly scented.
I wonder if anyone can suggest the most fragrant varieties from among the single, semi-double, and anemone-flowered forms.