Dunno about Memorial day, but here in Ireland I have just remarked to my wife that our P. off. 'Rubra Plena' (otherwise known as 'Granny's Peony' was very poor this year as well. About 5 blooms after an average of a dozen. Strange. Mild winter? Some shade? Who knows?
It sure can be hard to say. Our area had a freak deep freeze very early on but then a very mild winter and early spring. But then I have the shade thing, and the sandy soil thing, and the I don't fertilize regularly thing...
Hope Granny's peony bounces back next year. Thanks for reading!