NMay said: 'Nightlife' is not a registered peony and is likely an existing registered plant for which the label has been lost (or ignored) and has been given a commercial or trade name - something I really do not like and that causes further confusion. Because of this, I would not expect a reputable vendor to carry this and I would not recommend purchasing it. I suspect the color of this photo has been manipulated. It would be difficult to find this colour tone in natural lighting in a herbaceous peony cultivar. If you are seeking out this colour in peonies, I would take a look at the woody peony 'Pluto'.
I purchased a Nightlife Peony from Springhill Nursery through Home Depot, and wow let me say you should avoid Springhill Nursery. What they sent me was a Peony finger, not a rhizome. I asked them to send me a new one, and it was better but still nothing to brag about either. True to your comment, the main complaint in reviews online is that the color of the plant is red, not purple. Perhaps the genetics are not stable and the coloration quickly reverts to some historical base.
Regarding Pluto, I should have said I want a herbaceous Peony, not a tree. This is going into a very narrow garden up against the side of a home. It will be next to a Sarah Bernhardt Peony, so the purple needs to be a darker shade.
What do you think of Peony "Purple Spider"? I see some at the John Scheepers website that look healthy.
